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Estimation and simulation of carbon emissions in Great Xi’an based on grid and patch-generated land-use simulation models
GAO Yu, LIU Huan, BAO Lijia, SHI Lin, WU Jiang
, Available online  , doi: 10.12357/cjea.20230081
Abstract(68) HTML (27) PDF(9)
Abstract:
Land use change leads to substantial changes in regional carbon emissions, and estimating changes in carbon emissions caused by land use change provides an important practical reference for promoting the regional realization of “dual carbon” goals. This study aimed to investigate the spatial and temporal evolution patterns of land use types and their carbon emission effects in the Great Xi’an area from 1990 to 2020 and to predict its future carbon emission characteristics. Therefore, in this study, carbon emissions and carbon intensity involving the study area were estimated based on the emission factor method on two scales, administrative units and grids, and carbon emission characteristics of the study area in 2025 and 2030 were simulated using a patch-generated land-use simulation model. The results showed that: 1) from 1990 to 2020, the area of cultivated land continued to decrease, with an average annual decrease of 21.86 km2; the fluctuation of forest land, grassland, and water areas decreased, with an average annual decrease of 0.28 km2, 1.69 km2 and 0.08 km2, respectively; and construction land area continued to expand, with an average annual expansion area of 23.88 km2. The area of unused land fluctuated and increased by 1.14 km2. 2) From 1990 to 2020, carbon emissions in Great Xi’an increased from 280.00 t∙a−1 to 2342.27 t∙a−1, with an average annual growth of 68.74 t. From 2005 to 2010, it had the fastest growth rate of carbon emissions with an average annual growth of 125.86 t, whereas from 1990 to 2000, these grew at the slowest rate, averaging only 10.06 t per year. Whereas spatial distribution patterns were generally high in the south and low in the north, carbon emissions of Chang’an District in the south of the study area were much higher than those of Yanliang District in the north. 3) From 1990 to 2020, the maximum carbon emission intensity in Great Xi’an increased from 7461.94 t(C)∙km−2∙a−1 to 45 400.90 t(C)∙km−2∙a−1, an increase of nearly five-fold. In terms of space, the carbon emission intensity in the region always exhibited a distribution pattern of high in the north and low in the south, the carbon emission intensity of the main city of Great Xi’an was much higher than that of other regions. 4) Between 2025 and 2030, cropland and forest land will continue to be the primary land-use types in the Great Xi’an area, with the sum of their areas accounting for 63.53% and 62.45% of the total study area, respectively. From 2020 to 2030, the areas of cropland, forest land, water, and unused land in the region will continue to decrease, whereas the areas of grassland and construction land will increase. The total carbon emission increased by 2.96×107 t(C)∙a−1,, and the carbon emission intensity revealed a distribution pattern of high in the east and low in the west. Carbon emissions and their intensity in the Great Xi’an region have increased rapidly over the past 30 years.
The mitigation technologies for organized emissions of ammonia and greenhouse gas from livestock farms
Li Si, ZHANG Xiaohang, WANG Xuan, MA Lin
, Available online  , doi: 10.12357/cjea.20230238
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Abstract:
The end treatment technology for ammonia and greenhouse gas emissions (NH3, N2O, CH4) from livestock farms has received widespread attention and continuous research from scholars both domestically and internationally in recent years. However, the gas emission patterns and priorities of control in different livestock manure management stages are still unclear. A comprehensive comparison of treatment effects, costs, and applicable scenarios of different treatment technologies are uncertain, lacking a technical system for multi gas reduction. Therefore, this study systematically reviewed the published literature and used data mining methods to analyze the gas emission characteristics, priority characteristics, emission reduction technologies, and application potential of the livestock house, solid manure storage, liquid manure storage, and solid manure composting processes of pig, chicken, cattle, and sheep manure management. The emission reduction technology characteristics that match the gas emissions priority were summarized. The emission reduction technologies for NH3, N2O, and CH4 were discussed. The various technical principles and potential effects of NH3, N2O, and CH4 emission reduction were discussed, and the priority and potential technical approaches for gas resistance control in various stages of manure pollution management process were explored. These works could provide support for the combination and design of different technologies for the treatment of tail gas discharged from livestock farms, in order to achieve the goal of reducing ammonia and greenhouse gas emissions. Pointing to the shortcomings of existing end treatment technologies, this study looks forward to the research direction of NH3, N2O, and CH4 end treatment technology, aiming to provide a basis for the design of tail gas treatment processes and future technology research and development in livestock farms.
Research on the relationship between open innovation and provincial agricultural green development based on environmental regulation moderation
LEI Qinhua, SU Shipeng, SUN Xiaoxia
, Available online  , doi: 10.12357/cjea.20230245
Abstract(49) HTML (21) PDF(8)
Abstract:
In the face of the realistic dilemma of low efficiency in agricultural resource utilization, long cycle of agricultural technology research and development, and great uncertainty, open innovation is an important way to realize the green development of agriculture and is the key to achieving high-quality agricultural development. To reveal the mechanism of open innovation in agricultural green development, this study constructed an evaluation index system for agricultural green development based on four aspects, ecological conservation, resource conservation, environmental friendliness, and economic benefits, and evaluated the level of agricultural green development in various regions. Then, by constructing a nonlinear adjustment model, panel data from 31 provinces (excluding Hong Kong, Macao, and Taiwan) in China from 2010 to 2020 were used to verify whether open innovation can better promote the green development of agriculture. The results indicated the following: 1) The comprehensive evaluation result of China’s green agricultural development was 0.411, indicating that the overall level of green agricultural development was relatively low, and individual differences between provinces were significant and showed an expanding trend. Beijing had the highest growth rate in the level of green agricultural development, while Heilongjiang had the lowest. Fujian, Beijing, Tibet, and Beijing had the highest evaluations in terms of ecological conservation, resource conservation, environmental friendliness, and economic benefits, respectively. 2) Open innovation and agricultural green development presented a positive “U”-shaped nonlinear relationship, that was, there was a turning point in the impact of open innovation on agricultural green development. When open innovation investment was low, it was not conducive to the green development of agriculture. When the level of open innovation exceeded 15.3761, open innovation played a significant role in promoting green agricultural development. A robustness test also confirmed the nonlinear effect of open innovation on agricultural green development. In 2020, 11 provinces, including Tibet, Hainan, and Qinghai, were still in the suppression stage, while 20 provinces, including Beijing, Shanghai, and Guangdong, were in the promotion stage. 3) Environmental regulation positively regulated the nonlinear relationship between open innovation and agricultural green development, that was, at a higher level of environmental regulation, the inflection point of the positive effect of open innovation on agricultural green development moved to the left, and the impact rate was greater. 4) Open innovation had a differential impact on agricultural green development due to the different types of open innovation and dominant types, both inbound and outbound open innovation had a positive “U”-shaped nonlinear relationship with agricultural green development, but compared with outbound open innovation, inbound open innovation had a stronger driving effect on agricultural green development. At the same time, when outbound open innovation was greater than inbound open innovation, open innovation had a stronger driving effect on agricultural green development. According to the research results, it was proposed that areas with low open innovation should increase the cultivation of new agricultural business entities and improve absorption capacity, while areas with high levels of open innovation should focus on the construction of open innovation platforms and accelerate the flow of open innovation resources. Scientific formulation of environmental regulation policies, and improvement of environmental regulation intensity should be reinforced in low open innovation areas.
Effect of fertilization types on antibiotic resistance genes and bacterial community in vegetable fields
ZHENG Ziying, DING Lin, YANG Jing, HAN Wanxue, LIU Jin, WANG Xinzhen, WANG Fenghua
, Available online  , doi: 10.12357/cjea.20230270
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The farmland ecosystem is an essential source and sink for antibiotic resistance genes (ARGs), and livestock manure application is a great contributor to ARGs in the soil. Massive application of livestock manure in vegetable fields has intensified the pollution of ARGs in soil. Consumption of edible raw vegetables is one of the most direct ways to transfer ARGs from the soil-plant system to humans, which causes a potential threat to human health. However, there are few studies related to the effects of different fertilization types on ARGs and bacterial communities in vegetable fields. In this study, 21 soil samples (0-20 cm) were collected from vegetable fields with application of different fertilizer types (i.e., fresh fowl manure, fresh sheep manure, fresh cattle manure, commercial organic fertilizer, and chemical fertilizer) in Hebei province. The distributions and characteristics of ARGs and bacterial communities in vegetable fields were investigated through real-time quantitative PCR and high-throughput sequencing techniques. Eight tetracycline resistance genes (tetA, tetC, tetG, tetL, tetO, tetM, tetW and tetQ), two sulfonamide resistance genes (sul1 and sul2), and one intI1 gene were detected in all the vegetable fields. The absolute abundance of sulfonamide resistance genes [9.96×109 copies·g−1 (dry soil)] was significantly higher than that of tetracycline resistance genes [1.07×109 copies·g−1 (dry soil)). The application of livestock manure and chemical fertilizer both significantly increased the abundance of ARGs in soil from vegetable fields. The highest abundance of ARGs [6.34×109 copies∙g−1 (dry soil)] was found in soil from vegetable fields with higher chemical fertilizer amendment, while the lowest abundance of ARGs [3.09×108 copies∙g−1(dry soil)] was found in vegetable soil with application of commercial organic fertilizer. In addition, the Shannon index and Chao1 index, representing the α diversity of soil bacterial community, were significantly higher in soil fertilized with livestock manure compared to higher chemical fertilizer application, but not in lower chemical fertilization soil, indicating that livestock manure application significantly increased the abundance and diversity of the soil bacterial community. Pearson’s correlation analysis showed that soil bacterial community structure was an important factor influencing the distribution of ARGs. Proteobacteriota, Bacteroidota, Acidobacteriota and Actinobacteriota were the dominant potential hosts of ARGs, and were significantly correlated with sulfonamide and tetracycline resistance genes (P<0.05). The distribution of ARGs was also impacted by soil organic matter and total nitrogen. The intI1 gene had significant and positive correlations with the sul2, tetG, tetQ and tetW genes, suggesting its crucial role in the dissemination of ARGs. In this study, the use of higher chemical fertilizers led to a significantly increased abundance of ARGs in the soil of vegetable fields, while the application of commercial organic fertilizers had the smallest effect on ARGs abundance. This study serves as a guide to evaluate the status of ARGs pollution in vegetable fields with different fertilization types.
Effects of flushing alkaline thermal hydrolysis liquid to promote Brassica chinensis and nitrogen invertase activity mechanistic research
WANG Yongliang, WU Chenrui, XUE Xiaorong, SUN Jinxin, LIU Xiaolin, YANG Zhiping, ZHANG Qiang, BAI Ju
, Available online  , doi: 10.12357/cjea.20230028
Abstract(59) HTML (24) PDF(4)
Abstract:
The polypeptide-rich liquid extracted from alkaline thermal hydrolysis (ATH) sludge has proven to be non-toxic and usable in agricultural production, resulting in a significant increase in crop growth. To explore the effect of ATH hydrolysate on nitrogen uptake and nitrogen metabolism regulation mechanism of Brassica chinensis, B. chinensis was flushed with ATH hydrolysate (0 mg·kg−1, 20.19 mg·kg−1, 40.38 mg·kg−1, 60.57 mg·kg−1, and 80.76 mg·kg−1) treatments, with no nitrogen fertilizer as the control in a pot experiemnt. The results showed that as the application rate of flushed ATH hydrolysate increased, all indices first increased and then decreased. When the ATH hydrolysate was flushed at 40.38 mg·kg−1, the nitrogen accumulation, yield, and quality of B. chinensis were higher than those of the control after harvest, and the nitrate content was the lowest. By fitting the nitrogen uptake and yield of B. chinensis, the optimal application amount of ATH hydrolysate was determined to be 121.48−127.59 kg·hm−2. Under the condition of 40.38 mg·kg−1 for potted B. chinensis, nitrate reductase (NR), nitrite reductase (NiR), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), and glutamine synthetase (GS) activities could maintain high activity. In the 2nd, 4th, and 6th weeks after final singling of seedlings, the NR activity increased 36.12%−64.74%, 16.64%−60.07%, and 7.34%−74.59%, NiR activity increased 19.81%−77.69%, 2.53%−43.08%, and 7.08%−74.13%, GDH activity increased 9.02%−59.87%, 27.29%−75.51%, and 13.86%−55.18%, GS activity increased 3.97%−15.12%, 4.97%−55.01% and 9.02%−54.79%, and GOGAT activity increased 23.85%−74.24%, 8.78%−77.86%, and 22.15%−92.72%. Redundancy analysis showed that GOGAT in B. chinensis was the main factor determining the yield, nitrogen utilization rate, and nitrogen absorption rate, with a significant positive correlation. The ATH hydrolysate solution had a significant influence on the yield of B. chinensis and the activities of enzymes related to nitrogen absorption and transformation under different flushing rates. An appropriate amount of ATH hydrolysate increases the activity of nitrogen-related invertase in B. chinensis, thereby improving the absorption and utilization of nitrogen and yield. At the same time, it also showed that ATH solution can be used as a new type of fertilizer, which not only solves the problem of sludge but also improves the yield and nutrient absorption of B. chinensis.
Spatial and temporal evolution of landscape ecological security and its influencing factors in the Yangtze River Economic Belt from the perspective of production-living-ecological space in the past 40 years
ZHANG Xiang, ZHANG Shichao, ZHANG Xuanyun, LIU Jingyu, XUE Xiufeng
, Available online  , doi: 10.12357/cjea.20230138
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The Yangtze River Economic Belt is the leading demonstration belt for ecological civilization construction, and its spatial and temporal pattern of production-living-ecological space profoundly impacts landscape ecology security and people’s blessedness. Based on the remote sensing monitoring data of land use in 1980, 1990, 2010, and 2020, and considering the corresponding relationship between production-living-ecological space and land use types, this study analyzed the spatial-temporal evolution characteristics of landscape ecology security in the Yangtze River Economic Belt from 1980 to 2020 by using a landscape ecology security assessment model, spatial autocorrelation analysis, and other methods. And the geographic detectors was usted to explore the impact mechanisms of changes in natural conditions, social economy, and land use. The results showed that: 1) from 1980 to 2020, the land space of the Yangtze River Economic Belt was mainly ecological space, followed by production space and living space. The mutual conversion between production space and ecological space, and production space and living space, were dominant. 2) The overall landscape ecology security level of the production-living-ecological space in the Yangtze River Economic Belt from 1980 to 2020 showed an increasing trend. Among them, the unsafe zones of production space first decreased and then increased slightly; the unsafe zones of living space decreased year by year, whereas the moderately safe zones and safer zones expanded, and the safer zones of ecological space showed a fluctuating upward trend. 3) The spatial differentiation of landscape ecology security in the Yangtze River Economic Belt was clear. Among them, the safe zones of production space and living space were mainly distributed in the three major urban clusters in the Yangtze River Economic Belt, whereas the safe zones of ecological space were concentrated in the mountainous areas in the middle and upper reaches of the Yangtze River, southern Jiangxi and southern Zhejiang. 4) The spatial pattern of landscape ecology security of the production-living-ecological space in the Yangtze River Economic Belt was relatively stable, but the internal regional differences were evident. The high-high aggregation areas were mainly distributed in western Sichuan, western Yunnan, parts of Guizhou, Hubei, Hunan, Jiangxi, and southern Zhejiang, whereas the low-low aggregation areas were mainly distributed in the three major urban agglomerations in the Yangtze River Economic Belt. 5) Land use significantly impacted the evolution of landscape ecology security patterns, followed by the social economy and natural conditions. Therefore, we should pay attention to optimizing the layout of the production-living-ecological space to improve the coordinated play of landscape ecology functions and promote the ecological civilization construction and sustainable development of the Yangtze River Economic Belt.
Does contract farming promote farmers’ organic agriculture adoption?-Counterfactual analysis based on survey data of western Hunan farmers
LU Yu, XIANG Ping’an, YU Liang, WANG Zilong
, Available online  , doi: 10.12357/cjea.20230080
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Contract farming is an innovative method for developing organic agriculture in China. Clarifying whether contract farming promotes farmers’ adoption of organic agriculture can provide a decision-making basis for promoting organic agriculture in China. This study applied the propensity score matching method to construct a counterfactual analysis framework to test the treatment effects and heterogeneity of contract farming on farmers’ organic agriculture adoption based on farm-level survey data of 450 farmers from Baojing, Lanshan, Guzhang, Yongshun and Huayuan counties of Hunan Province. Our empirical results showed that contract farming plays a significant role in promoting farmers’ adoption of organic agriculture. The average treatment effect estimated based on five score matching methods showed that compared with farmers who did not participate in contract farming, the average treatment effect of farmers who participated in contract agriculture was 0.45−0.54. Moreover, for farmers from national organic product demonstration areas, with low awareness of organic agriculture, risk-averse farmers, and small-scale and part-time farmers, the average treatment effect of contract farming on organic agriculture adoption was more notable. Therefore, the government should encourage farmers to participate in contract farming. Furthermore, considering the heterogeneity of the treatment effect of contract farming on farmers’ adoption of organic agriculture, the government should develop contract farming modes that are suitable for farmers with different endowment constraints, risk attitudes, and organic agriculture cognition.
Sensitivity analysis and optimization of leaf area index related parameters of dryland wheat based on APSIM model
WEI Xuehou, NIE Zhigang
, Available online  , doi: 10.12357/cjea.20230345
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Crop growth model parameterization is characterized by a large number of parameters and low efficiency of parameterization. In order to realize the rate determination of crop model parameters quickly and efficiently, and to promote the rapid application of crop models in localization. In this study, we used a combination of sensitivity analysis and intelligent optimization algorithm to adjust the parameters of the crop model, taking the experimental data (leaf area index) of dryland wheat in large fields in Mazichuan Village, Lijiabu Town, Dingxi District, Dingxi City, Gansu Province (2002−2004), and Anjiagou Village, Fengxiang Town (2015−2017), as a reference. Using the Extened Fourier Amplitude Sensitivity Test (EFAST) method, the sensitivity analysis of 23 parameters of the APSIM-wheat dryland wheat leaf growth submodel was carried out with the help of simlab software, and the sensitivity coefficients of each parameter to the model results were obtained. On this basis, the parameters with larger first-order sensitivity index and global sensitivity index are selected as the optimization parameters, and then the R language is used to construct the algorithmic fitness function, implement the particle swarm optimization algorithm, and run the APSIM-wheat model to optimize the parameters automatically, so as to realize the fast and effective determination of the model parameters. The results showed that: 1) The six parameters most sensitive to the leaf growth model of dryland wheat were, in descending order, maximum specific leaf area, nitrogen limiting factor for leaf growth, cumulative emergence to nodulation temperature, extinction coefficient, cumulative nodulation to flowering temperature, and transpiration efficiency coefficient; 2) Optimization of parameters in the leaf growth submodel for dryland wheat resulted in a maximum specific leaf area of 26,652 mm2∙g−1 at a leaf area index of 0, a nitrogen limiting factor for leaf growth of 0.96, a cumulative temperature from emergence to nodulation of 382 ℃·d, an extinction coefficient of 0.44, a cumulative temperature from nodulation to anthesis of 542 ℃·d , and a transpiration efficiency coefficient of 0.0056. 3) After the optimization of the above parameters, the mean value of the Root Mean Square Error between the measured and simulated values of the leaf area index decreased from 0.080 to 0.042 before the optimization of the parameters, the mean value of the Normalized Root Mean Square Error decreased from 11.54% to 6.10%, and the mean value of the model validity index increased from 0.962 to 0.988, which indicated that the simulation of the leaf area index was better after the optimization. Compared with the traditional manual trial-and-error method, this method avoids the uncertainty of the optimization parameters, can quickly and efficiently find the important parameters of the model, and realizes the automatic parameter rate fixing, improves the efficiency of model parameter rate fixing, improves the problem of many parameters and low efficiency in the process of model rate fixing, and enables the model to be applied faster locally, so that it can better guide the agricultural production. The methodology of this study is also instructive for parameter tuning optimization of other crop modules in the APSIM-wheat model.
Impact of cultivated land operating scale on farmers’ rice production ecological efficiency: a case of Changde City
WEN Gaohui, HUANG Danni, XIE Yilin, HU Xianhui
, Available online  , doi: 10.12357/cjea.20230294
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Improving the rice production ecological efficiency is the key pathway to achieve the dual goals of guarantee of the stable growth of grain production and reduction of the environmental losses of cultivated land use. Cultivated land is one of the most basic production means in agricultural production activities. Therefore, it is of great significance for promoting moderate scale agricultural operating and cultivated land sustainable utilization to explore the impact of cultivated land operating scale on farmers’ rice production ecological efficiency. Unlike other studies that mostly focus on the medium and macro dimension of cities and provinces, this study is based on the micro dimension of grain production - farmers’ perspective. Moreover, the conclusions obtained from this study can make up for the lack in previous studies of targeted exploration on the impact mechanism of cultivated land operating scale on farmers’ rice production (ecological) efficiency and whether there is a non-linear relationship between them. Using 416 questionnaire survey data of farmers in Changde City, the random frontier analysis method is used to construct an efficiency calculation model and an impact model for empirical testing the relationship between cultivated land operating scale and the farmers’ rice production ecological efficiency. The results was shown as follows. 1) The farmers’ scale level and rice production ecological efficiency need to be improved. Among the sample farmers, the number of smaller operating scale farmers was the highest, accounting for 94.95% of the total sample. This indicated that smaller scale farmers were still the main force of agricultural production. The average of farmers’ rice production ecological efficiency was 0.830 with 0.170 rooms for improvement. 2) The cultivated land operating scale had a significant impact on the farmers’ rice production ecological efficiency. The farmers’ rice production ecological efficiency tended to increase then decrease with the expansion of cultivated land operating scale. Their relationship was non simple linear but exhibited an “inverted U” with an inflection point located in the range of 1.2−1.4 hm2. It was not necessarily true that the larger cultivated land operating scale, the higher farmers’ rice production ecological efficiency. The blind expansion of cultivated land operating scale could lead to a decrease in the farmers’ rice production ecological efficiency. Therefore, it is necessary to promote cultivated land moderate scale operation. 3) The farmers’ rice production ecological efficiency was also significantly positively affected by the education level of the head of household, dependency ratio and proportion of agricultural income, as well as significantly negatively affected by the age of the head of household. Therefore, we have to recognize that small-scale farmers will exist for a long time. Based on this, we should further enlarge the plot size to promote the cultivated land moderate scale operation, and promote the cultivated land concentration to reduce the degree of cultivated land fragmentation. At the same time, the government not only should continuously promote fertilizer reduction and efficiency improvement to accelerate the development of low-carbon agriculture, but also need to cultivate new farmers and increase supports for them to promote the ecological transformation of rice production.
Evaluation of relative soil moisture from CMA Land Data Assimilation System at different spatiotemporal scales in China
ZHANG Lei, GUO Anhong, HE Liang, WU Menxin, ZHAO Xiaofeng, TAN Fangying
, Available online  , doi: 10.12357/cjea.20230021
Abstract(83) HTML (73) PDF(8)
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Based on daily relative soil moisture from the CMA Land Data Assimilation System (CLDAS) and hourly relative soil moisture from automatic soil moisture stations during 2020−2021, CLDAS relative soil moisture was evaluated in terms of accuracy and suitability by using multiple statistic indices at temporal scales of day and month as well as spatial scales of station and region. The results showed consistent daily variation in CLDAS relative soil moisture and observed relative soil moisture. CLDAS relative soil moisture at depths of 0−10 cm and 0−20 cm was close to the observed relative soil moisture, whereas CLDAS relative soil moisture at a depth of 0−50 cm was smaller than the observed relative soil moisture. The correlation coefficients between CLDAS relative soil moisture and observed relative soil moisture at the three depths were generally greater than 0.6, between which the root mean square errors (RMSE) were smaller than 30%. At the regional scale, the correlation coefficient between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−10 cm was 0.78−0.95, with the largest value in South China. The RMSE between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−10 cm was 5.70%−17.26%, with the smallest value in East China. The bias between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−10 cm was −6.63%−15.80%, with the smallest absolute value in Central China. At a depth of 0−20 cm, the correlation coefficient between CLDAS relative soil moisture and observed relative soil moisture was 0.78−0.95, with the largest value in Northeast China and Inner Mongolia. The RMSE between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−20 cm was 4.45%−14.03%, with the smallest value in East China. The bias between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−20 cm was −5.36%−12.56%, with the smallest absolute value in East China. At a depth of 0−50 cm, the correlation coefficient between CLDAS relative soil moisture and observed relative soil moisture was 0.68−0.97, with the largest value in Northeast China. The RMSE between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−50 cm was 4.00%−15.83%, with the smallest value in East China. The bias between CLDAS relative soil moisture and observed relative soil moisture at a depth of 0−50 cm was −9.83%−9.62%, with the smallest absolute value in Northeast China. The correlation coefficients between monthly CLDAS relative soil moisture and observed relative soil moisture were generally high, with larger values between June and October. The RMSE between monthly CLDAS relative soil moisture and observed relative soil moisture was smaller than 15%, with the smallest value in East China. Overall, CLDAS relative soil moisture performed well in East China, Central China, and Northeast China at the spatial scale and during June−October at the temporal scale.
Research progress in source-sink landscape pattern analysis based on non-point source pollution processes in watersheds
WANG Jinliang, TAN Shaojun, LI Mengbing, NI Jiupai, ZHOU Bingjuan
, Available online  , doi: 10.12357/cjea.20221001
Abstract(83) HTML (41) PDF(13)
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Source-sink landscape theory is recommended as an effective way to couple landscape pattern and non-point source pollution processes. A reasonable source-sink landscape pattern layout aids in minimizing nonpoint source pollution risk by lowering non-point source pollution production. In this study, based on previous research results and literature reviews, advances in source-sink landscape pattern analysis based on non-point source pollution processes were systematically reviewed from three perspectives, including distinction of source-sink landscapes, quantization of source-sink landscape patterns, and the indication of source-sink landscapes to non-point source pollutants. To investigate the source-sink landscape based on non-point source pollution, the current research primarily maintains the sense of traditional landscape patterns, and it is necessary to consider spatial coupling relationships and comprehensive functions of multiple elements in order to better distinguish the source-sink landscape ownership in non-point source pollution processes. For analysis of source-sink landscape patterns, the classical location-weighted landscape contrast index is only suitable for watersheds or regions with similar environmental backgrounds. Therefore, it is necessary to consider quantifying more landscape factors to construct or improve the source and sink landscape pattern indices more comprehensively and then optimize the source-sink landscape pattern configuration and reduce risks to watershed landscape ecological security. Finally, the main non-point source pollutants in this study of source-sink landscape patterns were mainly traditional non-point source pollutants such as nitrogen and phosphorus. Therefore, it is necessary to expand source-sink landscape pattern analysis to indicate more non-point source pollutants in order to provide reference benchmarks for future research to better reflect coupling relationship between watershed landscape patterns and non-point source pollution processes.
Research progress in investigating the effects of AHLs-mediated quorum sensing and quorum quenching on the plant-rhizosphere microbial interactions*
ZHANG Qingxu, LI Jianjuan, GUO Yue, WANG Yanyan, PENG Yanhui, WANG Yuhua, HU Mingyue, LIN Wenxiong, WU Zeyan
, Available online  , doi: 10.12357/cjea.20230414
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The rhizosphere is a unique environment that arises from the interaction between plant roots and soil microorganisms. The metagenome of the microbial community in the rhizosphere plays a crucial role in shaping the plant microbiome. The interaction between plants and rhizosphere microorganisms is a complex process. In the rhizosphere environment, the microbial community recruits specific microorganisms through intricate signaling mechanisms within and between species. This coordination and control of the mixed community ultimately impacts the growth, development and health of plants. From an academic perspective, rhizosphere signaling mechanisms can be categorized into three primary types. Firstly, plants transmit signals to microorganisms by secreting low molecular weight molecules. Secondly, there is inter- and intraspecific microbial signaling. Lastly, microorganisms transmit signals to plants through compounds they produce. Rhizosphere microbes utilize quorum sensing (QS) to autonomously generate and release distinct signaling molecules, enabling them to detect variations in their concentrations and thereby regulate microbial quorum behavior. QS is a bacterial intercellular communication mechanism that regulates the expression of numerous bacterial genes, which are involved in various plant-microbe interactions. These interactions encompass functions such as biofilm formation, nitrogen fixation, hydrolysis, enzyme and extracellular polysaccharide synthesis, toxin production, cell movement, and intercellular connectivity. QS systems are characterized by the synthesis and release of specific signaling molecules. This process is crucial in rhizosphere communication as it enables the transmission of inter- and intraspecific information through the necessary signaling molecules. Due to the high density and diversity of rhizosphere bacteria, the rhizosphere may facilitate the transmission of QS signals. Additionally, these signaling molecules aid in the colonization of plant root surfaces or other rhizosphere-related areas by rhizosphere bacteria through gene expression mediated by QS. Recent research has revealed the presence of N-acyl-homoserine lactones (AHLs), diketopiperazines (DKPs), diffusible signaling factor (DSFs), secondary metabolites, phytohormonelike molecules and other QS signaling molecules in rhizosphere soil bacteria. AHLs are the most extensively studied quorum sensing signaling molecules in bacteria. They not only mediate bacterial quorum sensing, but also have a significant impact on the interaction between plants and rhizosphere microorganisms. This includes the colonization of rhizosphere microorganisms, the maintenance of soil ecosystems and the effects on plant growth. An in-depth understanding of the quorum sensing mechanism mediated by AHLs holds significant importance in promoting agricultural production, enhancing plant health, and fostering sustainable development. This article presents a review of the quorum sensing mechanism mediated by AHLs and discusses the regulatory role of AHLs in the interaction between plants and rhizosphere microorganisms. It explores the beneficial effects of AHLs on plant growth and development, stress tolerance and disease resistance, as well as the harmful effects of rhizosphere pathogenic bacteria on plants due to AHLs-mediated regulation of the QS system. Additionally, the article explores the impact of AHLs-based quorum quenching on plant-rhizosphere microbial interactions, aiming to provide valuable insights for plant health and agricultural production. The article also proposes new ideas and methods to promote the development of sustainable agriculture.
Advances in research involving deep incorporation of enriched straw on soil quality
RAO Yueyue, ZHOU Shunli, HUANG Yi, DOU Sen, DAI Hongcui, WEN Yuan
, Available online  , doi: 10.12357/cjea.20230145
Abstract(87) HTML (26) PDF(13)
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China’s agricultural production is facing the problems of increasing amounts of straw, shallow plow layers, low fertility, and compacted soils. In the past, the management of agricultural land concentrated on topsoil, resulting in the emergence of these phenomena. Until recently, the management of deep soils has received considerable attention from researchers, and various innovative field measures have emerged. The deep incorporation of enriched straw is a novel and efficient straw management approach that has advantages for the efficient use of crop residues, improvement of soil fertility and productivity, and enhancement of agricultural soil quality. This approach can break-up compacted soil in the bottom layer of the plow, alleviate the problem of microorganisms competing with crops for nitrogen, mitigate the negative effects on the quality of sowing and seedlings, improve the quality of soil in cultivated farmlands, and realize the high-quality and efficient use of straw resources. The deep incorporation of enriched straw provides a practical means for straw field treatment and land health conservation for intensive agricultural production in China. This study introduces a new straw return approach, the deep incorporation of enriched straw, summarizes the technical characteristics, results, research progress, and application potential of the novel approach and reviews the effects and mechanisms of deep straw incorporation on soil physical, chemical, and biological properties. Finally, we propose future priorities for the in-depth exploration of this novel approach, which will contribute to the longterm conservation of farmland.
Progress in research on preparation and application of oxygen nanobubbles in agriculture
ZHANG Yujia, XU Shuhan, LI Detian, CHUAN Limin, ZHU Yuanhong, WANG Feng, CAO Linkui, SHA Zhimin
, Available online  , doi: 10.12357/cjea.20230066
Abstract(55) HTML (16) PDF(8)
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To systematically understand the research progress and development trend involving oxygen nanobubbles and their applications in agriculture, this study summarized such researches through a analysis of publications, research strength, and research content with the research achievements of oxygen nanobubbles reported over the past 15 years in the first section. Second, the preparation methods and properties of oxygen nanobubbles were discussed, after which applications encompassing oxygen nanobubbles in the fields of agricultural production and agricultural environmental governance were emphatically reviewed, including promoting seed germination and crop growth, improving aquaculture production and economic benefits, reducing methane emissions in paddy fields, removing heavy metal pollutants and non-point source organic pollutants from soil. Finally, research emphasis and countermeasure suggestions regarding future oxygen nanobubble technology were prospected, including a detailed investigation of the oxygen-enhancing and action mechanisms of oxygen nanobubbles, which is beneficial for deeper application research, further development of preparative techniques for oxygen nanobubbles in the agriculture to reduce preparation costs and energy consumption, expansion of the applicability of oxygen nanobubble technology in agricultural production and environmental remediation, such as in different types of soil and crops, and largescale application research of oxygen nanobubbles. This study provides ideas and methods for both future basic and practical research surrounding oxygen nanobubble in agriculture-related fields.
Effects of nitrogen application rate and irrigation quota on yield and water and nitrogen utilization of post-spring wheat multiple cropping oilseed rape in Yellow River Irrigation Area
WEI Guangyuan, TAN JunLi, LI Hong, MA Bo, WANG Yuemei, TIAN Haimei, WANG Xina
, Available online  , doi: 10.12357/cjea.20230215
Abstract(63) HTML (28) PDF(23)
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The effects of successive oilseed rape cropping on the absorption and utilization of residual nitrogen and water, and nitrogen use efficiency in spring wheat stubble was studied to provide a theoretical basis for the effective utilization of residual nitrogen in post-spring wheat soil and for the prevention and control of agricultural non-point source pollution. A field trial was conducted to investigate the effects of nitrogen application (conventional application, 270 kg∙hm−2; reduced application, 202.5 kg∙hm−2; and no application, 0 kg∙hm−2) and irrigation quota (conventional irrigation, 400 mm; 20% water-saving irrigation, 320 mm; and 40% water-saving irrigation, 240 mm) on the yield and nitrogen uptake of succession oilseed rape crops, as well as the dynamic changes involving soil moisture and mineral nitrogen in the 0–100 cm layer. Nitrogen balance analysis was also conducted for both seasons. The results revealed that residual nitrogen in spring wheat stubble had a notable effect on the yield and nitrogen uptake of successive oilseed rape, and the residual effect of nitrogen fertilizer was positively correlated with the nitrogen applied to spring wheat stubble. When the nitrogen fertilizer application rate in spring wheat stubble was 270 kg·hm−2, the yield and nitrogen uptake of succession oilseed rape were the highest, reaching 6640 kg·hm−2 and 25.7 kg·hm−2, respectively, which were 11.8%–43.5% and 14.8%–58.8% higher than those under reduced or no nitrogen application. Irrigation quota had no substantial effect on oilseed rape yield but had a significant effect on nitrogen uptake. Nitrogen uptake of oilseed rape under conventional nitrogen application was increased by 9.6%−10.2% compared with the water-saving treatments. Compared with before planting, mineral nitrogen levels in the 0–100 cm soil layer under nitrogen application treatment after oilseed rape harvesting decreased by 18.8–96.1 kg·hm−2, indicating that succession oilseed rape cropping has an absorption capacity for residual nitrogen. The mineral nitrogen content of soil decreased by 96.1 kg·hm−2 under conventional nitrogen application and irrigation treatment compared with no or reduced nitrogen application. After the succession oilseed rape was crushed and turned over and returned to the field after winter freezing and thawing, the mineral nitrogen in the 0−100 cm soil layer increased by 86.1 to 171.8 kg·hm−2. This increase was positively correlated with the nitrogen application rate in the spring wheat season. Conventional nitrogen application combined with conventional irrigation had a small effect on soil water storage, and the residual effect of nitrogen fertilizer significantly improved irrigation water use efficiency, water use efficiency, and precipitation productivity of oilseed rape. Conventional nitrogen application combined with a 20% water-saving treatment had the highest irrigation water use efficiency and precipitation productivity, whereas conventional nitrogen application combined with a 40% water-saving treatment had the highest oilseed rape water use efficiency. Under these experimental conditions, the cumulative utilization rate of nitrogen fertilizer was the highest at 89.8% with reduced nitrogen combined with a 20% water-saving treatment. Nitrogen application rates of 270 kg·hm−2 and an irrigation quota of 320−400 mm considerably improved the yield, nitrogen uptake, water use efficiency, irrigation water use efficiency, and precipitation productivity of succession oilseed rape crops and reduced soil mineral nitrogen content under nitrogen application treatment. Turning over and returning the succession of oilseed rape to the field significantly increased soil mineral nitrogen content after winter freezing and thawing.
Classification of major crops using MODIS data in the Songhua River Basin
FENG Ying, GUO Ying, CHEN Xiaolu, LIU Mengzhu, SHEN Yanjun
, Available online  , doi: 10.12357/cjea.20230087
Abstract(107) HTML (24) PDF(18)
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In 2000, China launched a series of positive policies to promote agricultural development in Northeast China, thus causing a rapid expansion of the cropping scale and a change of cropping structure in the Songhua River Basin. It is important to reveal the changes in cropping structure in the Songhua River Basin to improve its future supply capacity, ensure national food security, and achieve the adjustment of food production. In this study, we selected the Songhua River Basin, a major grain-producing area in China, as the study area. Based on the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and land surface water index (LSWI) from MODIS data, a decision tree model was constructed by combining the phenological periods of different crops. The results of crop extraction were verified using observed datasets, verification points selected in Google Earth, and statistical almanac data. The values of extraction accuracy for rice, maize, and soybean were 0.9090, 0.9026, and 0.8200, respectively, with a Kappa coefficient of 0.79 and an overall accuracy of 0.84. The crop types in the Songhua River Basin were dominated by maize and supplemented by rice and soybean, forming a crop pattern of “soybean in the north, maize in the south, and rice near rivers”. The entire crop planting area of the Songhua River Basin was in a state of continuous expansion from 2000 to 2020, with the total planting area increasing from 95 556.26 km2 to 173 070.00 km2, an increase of 81.12%. The planting area of rice, maize, and soybean increased by 24 911.36 km2, 54 432.07 km2, and 20 719.77 km2, respectively. Overall, the proportion of the rice planting area to the total planting area increased by 8.56%, and those of maize and soybean increased by 16.86% and 0.39%, respectively. The planting areas of rice and maize increased significantly in most areas of the Songhua River Basin, and the rice expanded mainly in the areas near rivers. The planting area of soybean increased significantly in the eastern part of the northern part of the basin. The cities in the Songhua River Basin have formed a distinctive cropping structure, with most areas changing from a double-crop-dominant type to a maize-dominant type. In 2020, there was the addition of rice-dominant cities in the basin, the disappearance of maize-rice dominant cities and soybean-rice dominant cities, and the transformation of both maize-rice dominant cities and maize-soybean dominant cities into maize-dominant cities, with a gradual concentration of crop cropping types. The results of this study provide a scientific understanding of the adjustment of cropping structure and guidance of agricultural production in the Songhua River Basin.
Effects of maize and forage planting on the community structure of grounding-dwelling arthropods in oasis farmland
WANG Yongzhen, FENG Yilin, ZHAO Wenzhi, YANG Rong, LIU Jiliang
, Available online  , doi: 10.12357/cjea.20230176
Abstract(28) HTML (14) PDF(7)
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Intensive management of oasis farmland has negative effects on the diversity and function of grouding-dwelling animals. Increasing plant diversity by intercropping, crop rotation, and grazing can, however, contribute to enhancing soil animal diversity and the beneficial roles played by these organisms. Ground-dwelling arthropods comprise an important group of the soil macrofauna inhabiting oasis agroecosystems, the community composition and functional traits of which are particularly sensitive to changes in farmland plant coverage. In this study, Zhangye Oasis of Hexi Corridor, China, was selected as research area, and we systematically investigated the changes in the species composition and quantity of ground-dwelling arthropods during the growing and non-growing season of maize, vetch, and alfalfa using a trap method, and determined the influence of farmland crops and changes in grazing cover on arthropod community structure. We detected significant differences in the community composition of ground-dwelling arthropods in the maize, vetch, and alfalfa fields, as well as seasonal variation. The community composition in alfalfa fields was significantly different from that in both maize and vetch fields during the growing season, while less difference among fields was detected in the non-growing season. During the growing season, the activity density and species richness, diversity, and evenness indices of ground-dwelling arthropods in alfalfa fields were significantly higher than those of arthropods inhabiting the maize and vetch fields. In the non-growing season, the species richness and diversity indices of ground-dwelling arthropods in the alfalfa and vetch fields were significantly higher than those in maize fields. Furthermore, during the growing season, the activity density of predatory ground-dwelling arthropods in alfalfa fields was significantly higher than that of the predatory arthropods in the vetch and maize fields. Similarly, during both the growing and non-growing seasons, the activity density of phytophagous arthropods in alfalfa fields was significantly higher than that of phytophagous arthropods in the vetch and maize fields during both seasons, the activity density ratio of predatory to phytophagous arthropods in maize and vetch fields was higher than that in alfalfa fields. In addition, we found that the activity densities of herbivorous grounding-dwelling arthropods (including those in the families Acridoidea, Thripidae, Cicadellidae, and Aphididae) in alfalfa fields were significantly higher than those of herbivorous arthropods in the vetch and maize fields. Similarly, in the alfalfa fields, the activity densities of predatory ground-dwelling arthropods (including those in the families Gnaphosidae, Lycosidae, and Carabidae) were significantly higher than those in the other two fields. Collectively, the findings of this study revealed that the planting of perennial herbage in arid areas can contribute to increasing the number and diversity of beneficial populations among the grounding-dwelling arthropod community inhabiting oasis farmland, notably by promoting increases in the diversity and population size of herbivorous arthropod species. This will contribute to enhancing the biological control of farmland pests.
Impacts of field margin and organic practices on arthropod natural enemy and pest diversity in paddy field
MENG Xuan, LI Jianing, FAN Shunxiang, LIU Xinyu, LIU Yunhui
, Available online  , doi: 10.12357/cjea.20230395
Abstract(28) HTML (8) PDF(2)
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Although the expansion of agricultural land and intensive production have contributed to increased food production, the resulting high-intensity human disturbance and excessive use of agrochemicals have caused significant environmental damage. This has led to losses of biodiversity and the degradation of ecosystem services, and ultimately poses threats to both sustainable food production and human health. Therefore, it is crucial to explore more sustainable production management. Organic production at field scale and the establishment of flowering boundaries were considered as efficient measures for biodiversity and ecosystem services in European countries. Both of the above two practices were encouraged and financially supported within the framework of the Agricultural Environment Scheme. However, few studies have investigated whether organic practice and flowering boundary could effectively improve arthropods’ natural enemy and their control of pests in cultivated fields, particularly in paddy planting systems. In this study, we aimed to fill the knowledge gap by investigating the distribution and diversity of arthropods’ natural enemy and pests in paddy fields and their field margin and how vegetation on the field margin and vegetation on the boundary affects arthropods natural enemy and pest diversity in paddy field. Three treatments were set up, including conventional paddy field with traditional field margin (Con), organic paddy field with traditional field margin (Org) and organic paddy field with flowering boundary (OrgF). Arthropods were sampled in field margins and paddy fields with 5 m and 20 m away from the margin with the suction sampler. Vegetation coverage and diversity on the field margin were also investigated. The results showed as below. 1) A total of 9531 arthropods belonging to 50 families were caught, with 2653 natural enemies individuals from 28 families (including 2253 spiders individuals, belonging to 14 families and 41 species), and a total of 3971 pests individuals representing 18 families (dominated with Cicadellidae accounting for 84.01% of total pests individuals). 2)The richness of natural enemies in Org was greater than that in Con, the richness of natural enemies in OrgF was higher than that in Con and Org, and the abundance of natural enemies in OrgF was higher than that in Con. 3) In OrgF, the abundance and richness of natural enemies at different distances between the boundary of paddy field and the interior of the paddy field were significantly different, with greater richness of natural enemies in the paddy field with 20 m away from field margin than that with 5 m away, and the abundance of natural enemies was significantly higher at field margin than that at paddy field with 5 m away from boundary. 4) The richness and abundance of natural enemies and pest abundance in paddy fields and their boundary were positively correlated with the vegetation coverage at the paddy boundary. 5) The ratio of enemies to pests was highest in conventional paddy fields (Con), as most pests might be killed by broad-spectrum insecticides, followed by Org and OrgF, which have a great number of pests with only targeted bio-pesticide used. In conclusion, organic practices in the field and flowering boundary can effectively help with maintaining arthropod diversity and increasing natural enemies’ diversity in paddy field. However, to effectively control pests and biological control services, more understanding of the plant-arthropod relationship and careful selection of “correct” plant diversity are required.
Effects of organic and conventional management on soil carbon sequestration in tea gardens: comparison with forest land
ZHENG Yuting, HUANG Xinhui, LI Hao, WANG Biao, LI Panfeng, CUI Jixiao, SUI Peng, GAO Wangsheng, CHEN Yuanquan
, Available online  , doi: 10.12357/cjea.20230429
Abstract(16) HTML (9) PDF(11)
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In order to explore the effects of organic and conventional management methods on soil organic carbon in tea gardens, we selected three typical land use types in Simao District, Pu’er City, Yunnan Province to carry out the experiment. The three types of land use were conventionally managed tea garden, organically managed tea garden and nearby natural forest land. Based on the above three land use types, the present study has measured the contents of soil organic carbon (SOC), easily oxidizable organic carbon (EOC), non-liable organic carbon (NLOC), particulate organic carbon (POC) and mineral-associated organic carbon (MOC) in 0−20 cm and 20−40 cm soil layers in these three sample plots, estimated the distribution ratio of different types of organic carbon in soil and the soil carbon pool management index (CPMI), and analyzed the changes of content of soil organic carbon component and quality of soil carbon pool from the selected three land use types. The results showed as follows. 1) content and storage of SOC in 0−40 cm soil layer of the conventionally managed tea garden were significantly lower than those in natural forest land by 48.67−51.94% and 27.24~35.71% (P<0.05), respectively. The content and storage of SOC in 0−40 cm soil layer of the organically managed tea garden were 52.09~62.86% and 15.54~20.26% higher than those in the conventionally managed tea garden (P<0.05). 2) In 0−20 cm and 20−40 cm soil layer, the contents of EOC, NLOC, POC and MOC in soils from the tea garden under conventional management were significantly lower than those of natural forest land (P<0.05). While the contents of EOC, NLOC, POC and MOC in soils from the organically managed tea garden were significantly higher than those of the conventionally tea garden (P<0.05), which were higher by 46.39−57.89%, 54.24−66.15%, 80.87−121.01% and 40.07−46.28%, respectively. 3) Compared with natural forest land, the POC/SOC and NLOC/SOC of the tea garden under conventional management were lower, while those of the organically managed tea garden were higher than that of the conventionally managed tea garden. 4) Conventionally managed tea garden have higher CPAI and lower CPMI. The CPMI of the conventionally managed tea garden was 24.53−46.12% lower than that of the natural forest land (P<0.05), and the CPMI of organically managed tea garden was 67.88−100.33% higher than that of the conventionally managed tea garden (P<0.05). The above results showed that, compared with natural forest land, reclamation of the tea plantation with conventional management measures could reduce soil organic carbon content and soil carbon pool quality, resulting in a certain degree of land degradation. Compared with the deficiencies of conventional management, organic management is an effective measure to improve the quality of soil carbon pool in the tea plantation.
Impact of informatization of agricultural extension services on farmers’ scientific fertilization technology adoption decisions
WANG Pan, LI Gucheng, LIU Di
, Available online  , doi: 10.12357/cjea.20230301
Abstract(70) HTML (11) PDF(21)
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Continuously promoting scientific fertilization is a powerful support for achieving a stable food supply and constructing ecological civilization. In order to explore the effective strategies to promote the scientific fertilization by Chinese farmers in the context of digital village construction, this paper uses the Heckman two-stage model based on 1256 survey data of farmers in the rice producing areas of Hubei Province to explore the influence of informatization of agricultural extension services on the adoption decision of scientific fertilization technology by farmers in terms of “adoption behavior” and “the degree of adoption”, and analyzes the mechanism of the informatization of agricultural extension services on farmers’ scientific fertilization technology adoption decision by using the stepwise regression method. Results was showed as below. 1) Informatization of agricultural extension services had a significant positive effect on the adoption behavior and degree of adoption of scientific fertilization technologies by farmers. 2) There are differences in the effects of the informatization of agricultural extension services on different types of scientific fertilization technologies. Compared to the application of new fertilizers, the informatization of agricultural extension services has a more significant effect on farmers’ adoption of efficient fertilization technology. 3) Informatization of agricultural extension services promotes farmers’ scientific fertilization technology adoption behavior by improving benefit perception and promotes farmers’ scientific fertilization technology adoption behavior and adoption degree by reducing risk perception. Consequently, this paper puts forward policy recommendations to continuously enrich the forms and service contents of information-based agricultural extension services, improve the cooperative extension mechanism, and enhance the effectiveness of agricultural extension services through personalized services and precise extension.
Spatial and temporal distribution of water requirements and irrigation requirements of spring maize in Northeast China
LIU Xuchen, JING Feng, LOU Jiaxi, MA Shoutian, HUANG Chao, MENG Ye, CHEN Haiqing, WANG Pengfei, LIU Zhandong
, Available online  , doi: 10.12357/cjea.20230171
Abstract(94) HTML (42) PDF(7)
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Spring maize is one of the main grain crops grown in Northeast China. Drought and flood disasters frequently occur with irrational irrigation in this region; therefore, it is important to develop a rational irrigation system for spring maize production. In this study, the spatiotemporal distribution of water demand and shortage of spring maize in Northeast China was analyzed based on 70 years of experimental statistics from 26 stations in Northeast China, and crop water requirements were spatialized and analyzed using GIS technology. The results revealed the following: 1) the difference in water demand of spring maize was over 27 mm among wet, normal, dry, and extremely dry years, and the irrigation demand indices were 0.37, 0.44, 0.50, and 0.55, respectively. 2) Water shortages for spring maize first increased and then decreased from the northeast to the southwest, and the water shortage in the same hydrological year was higher in the west and lower in the east. The water requirements of spring maize increased gradually from the northeast to the southwest, and water requirements in the same hydrological year were higher in the southwest and lower in the northeast. Water requirements and shortages increased with increasing drought degree in the same region. The western region of the study area had the highest degree of dependence on irrigation, requiring long-term irrigation to ensure spring maize production. The planting structure should be adjusted appropriately and an inadequate irrigation system should be adopted to ensure water supply to spring maize during the critical period of water demand. Water requirements for spring maize were higher in eastern Liaoning, whereas water shortage and irrigation demand indices were lower than average because of abundant rainfall. Spring maize planting areas can be moderately expanded to maximize the use of rainfall and increase crop production and income.
Progress of bacterial wilt and its soil micro-ecological regulation in peanut
FANG Xiangyang, YU Taobing, YANG Lei, ZANG Huadong, ZENG Zhaohai, YANG Yadong
, Available online  , doi: 10.12357/cjea.20230189
Abstract(47) HTML (22) PDF(6)
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The bacterial wilt caused by Ralstonia solanacearum is one of the destructive soil-borne diseases around the world. It is widely spread, seriously harmful and difficult to control. Peanut is an important oil and cash crop in China, and it is also one of the crops that was seriously damaged by bacterial wilt. In recent years, it has been further aggravated by the phenomenon of continuous cropping, which has seriously threatened the development of peanut industry. This review takes the harm of bacterial wilt in peanut and its soil micro-ecological characteristics and control methods as the starting point. Then summarizes the occurrence, pathogenic bacteria, pathogenesis and control measures of the bacterial wilt in peanut. Firstly, we systematically and comprehensively summarize the four classification methods of Ralstonia solanacearum and conclude the pathogenesis of bacterial wilt in peanut. Secondly, based on the common soil characteristics of continuous cropping and bacterial wilt in peanut, we focus on the analysis of soil microenvironment and microorganisms and propose the corresponding soil micro-ecological regulation countermeasures, including soil physicochemical properties regulation, soil nutrient regulation, chemical and biological pesticide addition, and use of biocontrol strains. Finally, we provide a prospect for sustainable control of bacterial wilt in peanut based on soil micro-ecological regulations, aiming to provide references for the control of bacterial wilt in peanut and the high-quality development of peanut industry.
Trends and effects of agro-climatic resources and main meteorological disasters during Lycium barbarum L. growing seasons in Ningxia
XU Rui, YANG Jianling, LIU Jing, YAN Weixiong, MA Guofei, MA Junbin
, Available online  , doi: 10.12357/cjea.20230102
Abstract(145) HTML (25) PDF(14)
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In order to adapt to climate change, and rationally and efficiently use agro-climatic resources, and to facilitate the high-quality development of the Lycium barbarum L. industry, the climate change trends of the major meteorological factors during the L. barbarum growth period were evaluated, and the major meteorological disasters and their possible effects on the L. barbarum industry were investigated based on meteorological data from 10 national meteorological observation stations in L. barbarum-producing areas of Ningxia from 1961 to 2021. The results showed that the temperature and the number of high-temperature damage days during the growth period of L. barbarum increased. Compared the recent 10 years to the period of the 1960s, the average, maximum, and minimum temperature increased by 1.51 ℃∙a−1, 1.25 ℃∙a−1 and 2.06 ℃∙a−1, respectively; and the number of high-temperature damage days increased by 12.2 d∙a−1, which abruptly change in 2001, and after then the number of high-temperature damage days increased by 9.2 d∙a−1. Accordingly, the heat resources also showed a significant increasing trend. The active accumulated temperature (≥10 ℃) in summer and autumn double harvest areas increased by 266.1 ℃∙d∙a−1 and 132 ℃∙d∙a−1, and both of them abruptly changed in the 1990s, and after then increased by 10.6% and 9.1%. The active accumulated temperature (≥10 ℃) during the whole growth period of L. barbarum in single harvest areas increased by 319.9 ℃·d∙a−1, and abruptly changed in 1997, after then the integrated temperature increased by 11.4%. In addition, the interannual variability in precipitation and precipitation days was large in the L. barbarum area, and sunshine hours during the autumn fruit stage showed a decreasing trend. The growth process of L. barbarum was generally earlier by 11−13 d, and the entire growth period was prolonged owing to climate change. Among all meteorological disasters, the risk of spring frost disasters increased overall, and the middle to severe frost risk increased significantly since 2010. High-temperature damage days increased significantly and abruptly chaged in 2001, with an average increase of 12.2 d∙a−1 compared to before. The occurrence of rainy days increased, and the interannual variability was also large. Hailstorm disasters showed a decreasing trend, with an average annual decrease in six station-times over the past 10 years compared with the 1960s. This study analyzed the evolutionary trend of agro-climatic resources during the growth period of L. barbarum in Ningxia, reasonably explained the advantages and disadvantages of the changes in the growth and development of L. barbarum, and analyzed the changes in the main meteorological disasters affecting L. barbarum, providing a scientific reference for the quality improvement of L. barbarum in Ningxia. It is suggested that the major meteorological disasters affecting L. barbarum induced by climate change should be fully recognized, and early warning and defense capabilities should be strengthened.
An indicator system for effectiveness evaluation of ecological corridor restoration based on landscape patterns and ecosystem services
GUO Yujia, LIU Shiliang, DONG Yuhong, LIU Jiaju, LI Weishan
, Available online  , doi: 10.12357/cjea.20230079
Abstract(123) HTML (67) PDF(15)
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Implementing territorial ecological protection and restoration projects is important for promoting the China’s ecological civilization construction and ensuring national ecological security. China has actively explored and coordinated the integrated protection and restoration of mountains, rivers, forests, farmlands, lakes, and grasslands, and several important ecological protection and restoration projects at both the national and local levels since 2012. As an important component of territorial ecological protection and restoration, ecological corridors, which are zonal areas in the ecological environment, can effectively form regional-scale ecological networks to ensure regional ecological security. After the completion of projects, it is of great practical importance to evaluate the effectiveness of implementation of ecological restoration projects and analyze changes in ecological conditions before and after construction to improve ecological restoration work and optimize ecological safety barrier systems. However, there are several problems with the existing effectiveness evaluation of ecological corridor construction, such as a single evaluation objective, an incomplete evaluation indicator system, lack of principles of landscape ecology, and lack of evaluation of ecological restoration projects at different scales. Therefore, there is an urgent need to establish a systematic and comprehensive indicator system to evaluate the effectiveness of ecological corridor restoration. This study integrated ecosystem services indicators and proposed an indicator system for comprehensive effectiveness evaluation of ecological corridor restoration based on Pattern-Quality-Service. According to the characteristics of the ecological corridor, the effectiveness evaluation involved four dimensions: landscape patterns, biodiversity, habitat, and ecosystem services. These important evaluation points were determined at the project and ecological protection and restoration unit scales. By means of frequency analysis, expert consultation, and other methods, taking the improvement of ecosystem services as the restoration goal and referring to the existing specifications, the specific indicators that could objectively reflect the ecological restoration benefits of the project were screened. A comprehensive indicator system with clear quantitative methods and evaluation criteria was developed. The evaluation indicator system included four project layers, namely landscape pattern optimization, biodiversity conservation, habitat conservation and construction, and ecosystem service improvement, as well as 15 criteria layers and 41 indicators. Considering the integrated protection and restoration of various ecological elements in different regions, the evaluation indicators were divided into restrictive and recommended indicators, which were applied to common integral and individual optional conditions in the projects, respectively. Classifying these two indicators can enhance the flexibility of the evaluation indicator system and expand its applicability. In practice, the selection of evaluation indicators for the effectiveness of ecological restoration projects should be combined with the actual situation of the project based on this indicator system and common indicators should be selected for evaluation. Based on the evaluation results, ecological protection, and restoration work can be adjusted and corrected. In general, this study can better realize the ecological benefits of ecological corridors restoration and promote the construction practice of such ecological corridors. It could also provide a scientific reference and theoretical support for the planning, construction, implementation, and followup management of future territorial ecological restoration.
Root and leaf senescence of maize subject to spatial differentiation of soil water and CO2 in sandy fields with plastic film mulching
ZHOU Lifeng, YANG Yuxiang, YANG Rong
, Available online  , doi: 10.12357/cjea.20230289
Abstract(22) HTML (6) PDF(6)
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High intensive irrigation is commonly found in newly reclaimed oasis sandy land in arid area, which easily causes plant senescence of spring maize in farmland with plastic film mulching. The previous studies have found that land cover significantly affected soil moisture and soil aeration, but the data of spatial differentiation of soil moisture and soil aeration under mulching condition was lacking. In order to explore whether soil moisture and aeration causes plant senescence, an experiment was conducted to investigate the effects of plastic film mulching on spatial differentiation of soil water and partial pressure of soil CO2 (pCO2) in root zone, root growth, green leaf duration, leaf photosynthetic physiology, grain yield, and grain quality of spring maize in a sandy farmland in the Hexi Corridor (100°12′E, 39°20′N, 1370 m above sea level). Two treatments of plastic film mulching (PFM) and no mulching (NM) were set up in this experiment. In the current study, oven drying method was used to determine soil water content. Soil gas was collected by gas well method, which was composed of collecting pipe, transmission pipe, and a sampler. The CO2 concentration of gas samples was analysed by a gas chromatograph (Agilent 7890A, Agilent, Palo Alto, USA). Plant roots were sampled using a steel drilling, washed into a nylon mesh bag, scanned with root a scanner (EPSON Perfection V700) and then obtained root length density (RLD) using WinRHIZOPro software. Crop evapotranspiration was determined using water balance method. Soil moisture showed no significant difference in horizontal direction in NM treatment, whereas, the average soil moisture of mulched soil (narrow row and wide row at 5 cm distance from plants) was 28.1% (P<0.05), 15.2% (P<0.05) and 21.7% (P<0.05) higher than that under non-mulched soil (wide row at 25 cm distance from plants) before, 6-days after, and 9-days after irrigation. In contrast, soil pCO2 in mulched zone was 40% higher than that in the in non-mulched zone. Compared with NM treatment, the excessively high soil pCO2 (0.93%−1.27%) under mulched zone decreased the maize root activity by 19.7% at flower stage, but the root distribution and activity in the non-mulch zone increased by 15.8% and 9.6%, respectively. Compared with the NM, the leaf photosynthetic rate and transpiration rate in PFM were increased by 20.0% and 8.5% at the jointing stage, respectively, but the corresponding value were −40.0% and −18.0% respectively. In addition, compared with the NM, the senescence-start time and senescence-maximum time of green-leaves were 1.7 d and 7.1 d earlier in PFM, respectively, while the average and maximum green-leaves senescence rates were increased by 6.7% and 21.7% in PFM, respectively. The above effects of mulching did not significantly affect the yield of corn grain, but reduced the starch content and protein content of grain by 20.1% and 22.1%, respectively. The above results show that the excessively high soil pCO2 after maize flowering in the newly reclaimed oasis sandy land in the arid area may be an important reason of plant senescence and grain quality degradation, and it is recommended to take timely film-uncovering, controlled irrigation (e.g., deficit irrigation, root alternating irrigation) or aerated irrigation to improve soil aeration.
Research on the effects of rural land consolidation on agricultural carbon emissions: a quasi-natural experiment based on the high-standard farmland construction policy
XIONG Feixue, ZHAO Xinglei, GUO Ziyi, ZHU Shubin
, Available online  , doi: 10.12357/cjea.20230353
Abstract(31) HTML (15) PDF(9)
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Under the carbon emission pattern of “carbon peak and carbon neutral”, agricultural carbon emissions, as one of the main sources of greenhouse gases, has become a key area for emission reduction. High-standard farmland construction is regarded as an important measure to promote the green, low-carbon and high-quality development of agriculture. In-depth investigation of the effects and mechanisms of high-standard farmland construction policies on agricultural carbon emissions can provide an empirical basis for optimizing policy formulation and agricultural carbon emission reduction, which is of great significance in promoting the development of low-carbon agriculture. Based on the theory of scale economy and the theory of division of labor, this paper constructed a theoretical model of “high-standard farmland construction-agrochemical input intensity/socialized service-agricultural carbon emission”. Based on the panel data of 30 provinces in China from 2007 to 2017, this paper analyzed the impact and mechanism of high-standard farmland construction policy on agricultural carbon emission by using continuous differences-in-differences approach (DID) and mediation effect model. By measuring the agricultural carbon emissions of each province, this study found that the national agricultural carbon emissions showed an inverted U-shaped trend of rising at the beginning, then declining and reaching a peak in 2015. Regions such as Henan, Shandong, Hebei, Jiangsu and Anhui are at the forefront of agricultural carbon emissions nationwide, and regions such as Beijing, Shanghai, Tianjin, Hebei and Shandong have a higher rate of agricultural carbon emission reduction. The dynamic estimation results showed that the carbon reduction of the high-standard farmland construction policy had a lag effect, and the carbon reduction effect appeared in 2013 and continued to gradually increase. The results of the benchmark regression found that the high-standard farmland construction policy significantly suppressed agricultural carbon emissions. On average, when all other conditions remain unchanged, the implementation of high-standard farmland construction policy significantly reduced agricultural carbon emissions by 10.1%. The robustness tests was conducted using the approach of substituting variables and considering the interference of other relevant policies, and the results also confirmed the positive effect of the high-standard farmland construction policy on reducing agricultural carbon emissions. The results of the mechanism analysis showed that agricultural chemical input intensity and agricultural socialized services played a mediating effect in the process of reducing agricultural carbon emissions through the construction of high-standard farmland. The construction of high-standard farmland suppressed agricultural carbon emissions mainly through the reduction of agricultural chemical input intensity and the improvement of agricultural socialized services. Heterogeneity analysis reveals that the carbon reduction effect of the high-standard farmland construction policy mainly occurs in provinces with a high degree of land transfer and in non-food producing areas, while it does not play a corresponding carbon reduction effect in provinces with a low degree of land transfer and in food producing areas. Therefore, government should strengthen the construction of high-standard farmland, and differentiate the implementation of high-standard farmland construction policies according to local conditions and classifications, so as to give full play to its emission reduction effect. In addition, the government should also pay great attention to the role of agricultural chemicalization and agricultural socialized services in the carbon reduction effects.
Spatial distribution of cultivated land quality and potential for capacity improvement of paddy fields in South China
LI Yuhao, WANG Hongye, ZHANG Junda, WANG Xinyu, ZHANG Rui, YING Hao, CUI Zhenling
, Available online  , doi: 10.12357/cjea.20220783
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In order to clarify the spatial distribution and promotion potential of paddy cultivated land quality in South China, and to provide a scientific basis for realizing high and stable rice yield in South China, based on the regional evaluation data of cultivated land quality in South China carried out by the Cultivated Land Quality Monitoring and Protection Center of the Ministry of Agriculture and Rural Affairs of the Perople’s Republic of China in 2017, this study analyzed the spatial distribution of paddy cultivated land quality and its corresponding relationship with productivity in South China. The stochastic forest model was used to identify the main limiting factors that affect the capacity improvement. The spatial distribution law of the quality grade of paddy field in South China was “high in the middle and low around”. The fitting result of semi-variance function showed that the quality grade of paddy field in South China was in moderate spatial correlation (R2=0.95), the highest in Guangdong (3.82) and the lowest in Hainan (5.32). Among the evaluation indexes of cultivated land quality in South China, there was a great difference in the spatial distribution of soil nutrient indexes, and the spatial distribution of soil total nitrogen and slowly available potassium showed a strong spatial correlation, with the spatial distribution law of “high in the west and low in the east” and “high in the north and low in the south”, respectively. The contents of soil organic matter, available phosphorus and available potassium showed moderate spatial distribution correlation, with a decreasing spatial distribution trend from west to east, east to west and north to south, respectively. The overall soil pH was weakly acidic (5.40), with moderate spatial distribution correlation. Soil physical properties, site conditions, soil management and soil health were better in the east and worse in the west. There was a significant positive correlation between the quality grade of paddy field and the overall rice yield in South China (R2=0.9140), and the rice yield increased rapidly at first and then tended to slow down with the improvement of cultivated land quality. There was a significant positive correlation between the quality grade of paddy land and the sustainable index of rice yield in South China (R2=0.9333). The importance analysis of stochastic forest model showed that soil available phosphorus content, irrigation capacity and soil organic matter content were the most important factors affecting rice yield in South China. Scenario simulation showed that if the quality grade of paddy land in South China is improved by 0.5, 1.0, 1.5 respectively, the yield will increase by 7.91%, 14.94% and 21.24%, which is equivalent to saving 317 700 hm2, 563 500 hm2 and 759 500 hm2 of cultivated land. There is still great potential to improve the quality and production capacity of paddy farmland in South China. Improving the production capacity by improving the quality of cultivated land is of great significance to ensure food security and promote agricultural green production.
Influence of lateral recharge in mountainous areas on groundwater recharge and nitrate dynamics in Hutuo River alluvial-pluvial fan
SUN Heping, WANG Shiqin, ZHENG Wenbo, TAN Kangda, CAO Wengeng, SHEN Yanjun
, Available online  , doi: 10.12357/cjea.20230117
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Lateral recharge in mountainous areas is an important recharge source of alluvial-pluvial fan in the piedmont plain of North China, which affects the dynamics of quantity and quality of groundwater in plain areas. In recent years, the mechanism of lateral recharge in mountainous areas of groundwater in alluvial-pluvial fan and the its influences on the dynamics of nitrate in groundwater in plain areas is still unknown due to extreme climate and human activities. Through hydrological observation, hydro chemical, and isotope tracer methods across the Hutuo River alluvial-pluvial fan, we estimated the lateral recharge flux and nitrate transport flux in mountainous areas, revealed the recharge relationship between the lateral recharge in mountainous areas and the groundwater in plain areas, and analyzed the influence of the lateral recharge in mountainous areas on the distribution of groundwater nitrate. The sampling sites were divided into four sub-regions: the northern top part of the alluvial-pluvial fan of the Hutuo River (Zone Ⅰ), the middle of the fan (Zone Ⅱ), the fan margin area near the Hutuo River (Zone Ⅲ), and the southern part of the alluvial-pluvial fan (Zone Ⅳ) according to the hydrogeological conditions. The monitoring data of groundwater nitrate dynamics showed that the nitrate concentration of groundwater in the mountainous section of the northern Hutuo River was higher than that in the southern section, and the nitrate concentration of groundwater in Zone Ⅰ and Ⅱ of the northern alluvial-pluvial fan plain was higher than that in the Zone Ⅳ. Along the direction of groundwater flow, the mean concentration of groundwater nitrate showed a spatial distribution pattern of Zone Ⅰ (105.28 mg·L−1) >Zone Ⅱ (99.22 mg·L−1) >Zone Ⅳ (37.10 mg·L−1) >Zone Ⅲ (23.08 mg·L−1). It is revealed that the influenced area by lateral recharge in mountainous areas in the northern part of the alluvial-pluvial fan is the top and middle fan. However, the influenced area in the southern part of the alluvial-pluvial fan is mainly the top fan, because the groundwater flow field was changed by overexploitation. Darcy’s law was used to calculate the amount of lateral recharge in mountainous areas of the Hutuo River alluvial-pluvial fan from March 2022 to February 2023. Results showed that amount of lateral recharge was 2.10×108 m³, and the nitrate flux was 239.56×105 kg. Moreover, water and nitrate fluxes of lateral recharge in the northern mountainous area were greater than those in the south, which was also an important reason for affecting the spatial distribution of groundwater nitrate in the plain area. The impact of lateral recharge in mountainous areas on quantity and quality of groundwater in the alluvial-pluvial fan cannot be ignored. Therefore, it is of great significance to achieve comprehensive treatment at groundwater sources and reduce the concentration of groundwater pollutants in mountain area for non-point source pollution management and groundwater nitrate pollution prevention in the downstream plain area.
Effects of Pichia anomala and cellulase on methane production potential of sweet sorghum silage
REN Haiwei, LI Zhongqi, ZHAO Yaning, DING Wenhao, ZHANG Bingyun, LI Jinping, LU Dong, LIU Ruiyuan, LI Lianhua, SUN Yongming
, Available online  , doi: 10.12357/cjea.20230129
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The effects of Pichia anomala, cellulase, and a combination of both on the regulation of ensiling quality and methanogenic potential during anaerobic digestion of sweet sorghum were investigated in this study. Moreover, microbial community diversity during anaerobic digestion was analyzed using high-throughput DNA sequencing, and economic performance was evaluated to screen for inexpensive and highly efficient additives. The results revealed that the two additives improved the ensiling fermentation quality of sweet sorghum to different extents. The highest comprehensive assessment value was for the silages treated with the combination of P. anomala and cellulase (PC, 0.66), followed by 0.63 in silages treated with P. anomala alone (PA). PC was effective in preserving energy components such as water-soluble carbohydrates, crude protein, cellulose, and hemicellulose in sweet sorghum silage. The addition of the two could also reduce lignocellulosic components, such as acid detergent lignin, neutral detergent fiber, and acid detergent fiber and subsequently increase the content of lactic and acetic acid and enhance ensiling fermentation. In particular, there were more residual water-soluble carbohydrates and the highest lignin removal (62.55%) after PC treatment, and the well-preserved protein and the highest lactic and acetic acid content, 50.01 g·kg−1 and 18.35 g·kg−1 (based on dry matter, DM), were determined in PA silages. Ensiling pretreatment markedly improved the methanogenic potential of sweet sorghum. In particular, for PC, the maximum cumulative methane production was 457.70 mL(CH4)·g−1 (based on volatile solids, VS), which was increased by 30.13% compared to raw sweet sorghum, the maximum biodegradation rate was 72.39%, and the lag phase was decreased by 62.96% compared to raw sweet sorghum (CK). In comparison with CK, the maximum methane production rate in PA increased by 33.57%, and the lag phase decreased by 33.33%. The species richness of bacteria and archaea increased after sweet sorghum was treated with additives. Simultaneously, the use of different silage additives can affect the variation in bacterial community diversity with fermentation time but no such effect was observed in archaea. At the genus level, the dominant bacteria in the anaerobic digestion effluent were Fermentimonas and Clostridium_ sensu_stricto_1, which negatively correlated with pH and positively correlated with chemical oxygen demand (COD) and total volatile fatty acid (TVFA). The dominant archaea were Methanosarcina and Methanobrevibacter, where Methanosarcina was negatively correlated with COD and TVFA and positively correlated with pH. Methanobrevibacter was positively correlated with COD and TVFA concentrations and negatively correlated with pH. After the combined analysis of ensiling quality, methanogenic performance, and economy, it is recommended to use PA as a biological additive for ensiling pretreatment in practical production.
Seasonal effects of snow cover on soil soluble carbon and nitrogen content and microbial activity
WANG Enliang, WEI Chang
, Available online  , doi: 10.12357/cjea.20230323
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The problem of global warming is becoming more and more serious, and the complicated climate change situation leads to the obvious change of global snow cover pattern. Based on this, in order to explore the effects of future climate warming on physical and chemical properties of black soil in northeast China. This study adopted the method of artificial snow depth control from November 2020 to May 2022, and divided the plots in the test area into three treatment groups, namely, snow increase group (TS), snow removal group (TR) and control group (C). Soil environmental factors, available carbon and nitrogen content, microbial biomass, urease activity and sucrase activity were determined. The seasonal dynamic change process of each index was analyzed. Long-term field experiments show that snow removal can significantly reduce soil temperature and humidity. In addition, the lower soil temperature and humidity accelerated the release of soil nutrients and significantly increased the contents of soil organic nitrogen, nitrate nitrogen and ammonium nitrogen in early winter, while the opposite was true with snow treatment. However, from the beginning of the deep snow period, snow removal treatment caused the loss of soil organic carbon and inorganic nitrogen to a certain extent, and accelerated the release of soluble organic matter. Due to the effect of heat insulation of snow cover, snow addition treatment significantly increased the content of soil soluble organic matter compared with the other two treatments. Snow removal treatment keeps the soil microbial activity at a high level in most of the winter. However, at the end of winter, due to the rapid release of soluble organic matter under snow treatment, soil microorganisms under snow treatment absorb a large amount of nutrients and exist in a more suitable soil environment, which significantly increases the soil microbial activity under snow treatment. However, due to the loss of the heat insulation effect of snow cover, a large number of microorganisms were decomposed and died at this time, which significantly reduced the soil microbial activity. Before and after the test period, snow treatment significantly increased the soil microbial activity by 23.07 mg∙kg−1, and snow removal treatment significantly increased the soil microbial activity by 11.92 mg∙kg−1, with a difference of 93.5%. The decrease of snow cover significantly decreased the activities of soil urease and sucrase in most of the winter, and the activities of soil urease and sucrase were significantly increased by snow treatment. The experiment showed that the activities of these two enzymes were significantly increased by more than 10.5%. In summary, this study proved that the change of snow cover in the future will lead to changes in the dynamic change characteristics of soil available carbon and nitrogen and microbial activity, and the influence of snow cover change on soil enzyme activity will also indirectly affect the soil nutrient cycling process and change the physical and chemical properties of soil. The results of this study provide a theoretical foundation and scientific basis for further research on the material cycle of the terrestrial ecosystem in the black soil region of northeast China under the background of climate warming.
Characteristics of root-associated microbiomes and their responses to soil nitrogen levels in different wheat cultivars*
ZHENG Yuchong, ZHANG Linqi, LIU Binbin
, Available online  , doi: 10.12357/cjea.20230069
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Plant root-associated microorganisms play important roles in nutrient uptake and growth of the plant. In order to illustrate the differences of the root-associated microbial community structure of different wheat cultivars, four wheat cultivars (i.e., ‘Kenong 9204’, ‘Kenong 2011’, ‘Jing 411’ and ‘Bainong 207’) were planted under different nitrogen levels, and the rhizosphere and root samples were collected at tillering, jointing and filling stage. The bacteria diversity and community structure in rhizosphere soil and root endosphere of different wheat cultivars were analyzed using 16S rRNA gene high-throughput sequencing technology, and physiological parameters of wheat were determined. Compared with the other three cultivars, ‘Kenong 9204’ had higher aerial nitrogen accumulation in the three growth stages and under two nitrogen levels, except that at tillering stage with low nitrogen level. Proteobacteria and Actinobacteriota were the dominant bacteria in wheat rhizosphere soil and root endosphere bacterial communities. Compared with the other three cultivars, ‘Kenong 9204’ enriched Rhizobiales and Gemmatimonas in the rhizosphere soil bacterial community under low nitrogen level at jointing stage, and enriched Frankiales under high nitrogen level at filling stage. Correlation analysis showed that microorganisms, such as Arthrobacter, Streptomyces, Rubrobacter and Nocardioides, in rhizosphere soil bacterial communities were significantly positively correlated with aerial biomass and aerial nitrogen accumulation. Massilia, Arenimonas, Pseudomonas and Flavobacterium were significantly positively correlated with aerial nitrogen content. Taken together, our results indicated that wheat may affect nutrient uptake by regulating the composition of microbial community in the root zone, and this effect is cultivar-specific. This study provided useful information for understanding the plant-microbe interactions in wheat and for harnessing beneficial microbes for agricultural production.
Rainfall partitioning patterns for Pinus tabulaeformis forest in Taihang Mountains
GUO Bo, YANG Hui, LI Jiacong, ZHU Chunyu, ZHAO Yuhan, CAO Jiansheng, SHEN Yanjun
, Available online  , doi: 10.12357/cjea.20230172
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The Taihang Mountain Region is the ecological barrier and water source of North China Plain. In recent decades, with the implementation of Taihang Mountains Greening Project and other projects, the vegetation coverage in Taihang Mountain Region is recovering continuously, but the runoff in the mountains is rapidly declining. The mechanism of how the vegetation restoration affects the water yield is not clear. The process of rainfall partitioning is an important part of hydrological cycle. It is of great significance for the formation process of regional water yield and water resources. Pinus tabulaeformis is the main afforestation tree species in Taihang Mountain Region, which affects regional water resources. The rainfall partitioning of Pinus tabulaeformis forest in Taihang Mountain Region remains poorly understand. It is required to assess the applicability of the revised Gash model and revised Liu model. In this study, the rainfall partitioning in Pinus tabulaeformis forest is examined. The canopy interception was simulated by revised Gash model and revised Liu model. The results showed that 1) the rainfall amount was 450.8 mm during the study period, the average rainfall duration was 10.4 h, and the average rainfall intensity was 2.7 mm∙h−1. Furthermore, we found that the rainfall during the study period was mainly light rain. The canopy interception, throughfall and stemflow of Pinus tabulaeformis forest were 105.5 mm, 338.2 mm and 7.1 mm, respectively, accounting for 23.4%, 75.0% and 1.6% of the rainfall amount. 2) Throughfall and stemflow began to occur when the rainfall amount reached 1.7 mm and 5.5 mm, respectively. Significant linear relationships were found between the rainfall amount and throughfall amount. However, the relationship between rainfall amount and interception followed a power function. The throughfall percentage increased quickly with increasing rainfall amount, but when rainfall amount reached 11 mm, the throughfall percentage increased slowly. The interception percentage firstly decreased and then stabilized with increasing rainfall amount. 3) Based on the revised Gash model, the canopy interception, throughfall and stemflow were calculated to be 105.3 mm, 340.7 mm and 4.6 mm, respectively. The relative errors between the measured values and the simulated values were 0.2%, 0.8% and 34.7%, respectively. According to the revised Gash model simulation results, we found that the interception amount was dominated by canopy evaporation during rainfall ($ {\text{I}}_{\mathrm{s}} $), accounting for 55% of the interception simulation amount, followed by evaporation after cessation of rainfall ($ {\text{I}}_{\text{a}} $), accounting for 27.8% of the interception simulation amount. The revised Liu model calculated the interception as 96.0 mm, with a relative error of 9.0% between the measured and simulated values. The revised Gash model had lower relative errors in simulation compared with the Liu model. 4) Sensitivity analysis of the revised Gash model parameters showed that the mean evapotranspiration rate $ \left(\overline{\text{E}}\right) $ > mean rainfall intensity $ \left(\overline{\text{R}}\right) $ > canopy storage capacity $ (\text{S}\text{)} $ > canopy cover $ (\text{c}\text{)} $ > Trunk storage capacity $ \left({\text{S}}_{\text{t}}\right) $ > Stemflow coefficient ($ {p}_{\mathrm{t}} $). These results indicated that the typical Pinus tabulaeformis forest in Taihang Mountains can intercept 23.4% of rainfall amount. However, the revised Gash model can be used to predict the canopy interception of Pinus tabulaeformis forest, and provide a theoretical basis for water resources assessment and water conservation capacity improvement in mountainous areas.
Effects of late spring coldness on fungal communities in wheat rhizosphere soil at flowering stage
WANG Pengna, DAI Wenci, YU Min, WENG Ying, HUANG Jinwei, WU Yu, CAI Hongmei, GUO Jianpeng, GAO Sai, ZHENG Baoqiang, LI Jincai, CHEN Xiang
, Available online  , doi: 10.12357/cjea.20230017
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Due to global warming, late spring coldness is a major agrometeorological disaster frequently occurring in wheat production. The wheat yield can be reduced by 30%–50% in severe cases. Rhizosphere microorganisms endow wheat with stress resistance, and variations in their community structures and ecological functions reflect the adaptability of wheat to environmental changes. Studying the impact of late spring coldness on the structure and diversity of fungal communities in the rhizosphere soil of wheat is important for understanding the disaster mechanisms of wheat in response to late spring coldness. This study used wheat cultivars of ‘Xinmai 26’ (XM, sensitive to late spring coldness) and ‘Yannong 19’ (YN, resistant to late spring coldness) as experimental subjects. A pot experiment was conducted to artificially simulate late spring coldness during the anther differentiation period (a sensitive stage) of young ear differentiation of wheat. With 10 ℃ as the control treatment (CK), two low-temperature stress treatments were set at 2 ℃ (T1) and −2 ℃ (T2). The rhizosphere soil was collected at the wheat flowering stage, and changes in the fungal community structure and diversity in the rhizosphere soil of different wheat cultivars were determined by the Illumina high-throughput sequencing platform. Additionally, the aboveground and belowground biomass of the wheat plants were measured, and the root-to-shoot ratio was calculated. Compared with CK, the aboveground and belowground dry matter weight of the two wheat cultivars at the flowering stage under late spring coldness decreased by 1.65%−12.22% and 15.05%−35.49%, respectively, and the root-to-shoot ratio increased by 15.79%−36.08%, which had a greater effect on XM than YN. Late spring coldness significantly increased the relative abundance of Ascomycota but significantly decreased the relative abundance of Mortierellales, Mortierellaceae and Mortierella, with a greater decrease in XM as the degree of stress increased. For XM, in T2 treatment, the relative abundance of Mortierellaceae decreased by 54.70% compared with that of CK. The relative abundance of Agaricomycete fungi was significantly higher in YN than in XM under late spring coldness. The diversity analysis showed that late spring coldness significantly affected the diversity and richness of fungal communities in the wheat rhizosphere soil. The FUNGuild function prediction showed that the proportions of different ecological functional groups were affected by late spring coldness. The relative abundance of Endophytes was the highest, which decreased with the increase in late spring coldness. The wood saprotroph and plant pathogen were more abundant in XM_T2. In conclusion, late spring coldness decreased the aboveground and belowground biomass accumulation of wheat plants at the flowering stage, causing imbalanced growth and development of wheat roots and canopies, which was not conducive to yield. Late spring coldness significantly changed the community structure and diversity of wheat rhizosphere fungi; the degree of influence increased with an increase in the degree of stress, and the influence on XM was greater than that on YN. This study provides new insights into the disaster mechanism of late spring coldness in wheat from the perspective of rhizosphere microorganisms and provides theoretical support for exploring the response of the “root-soil-microbial” interaction system to late spring coldness from the perspective of the root-soil environment.
Effects and mechanisms of addition of different types of exogenous organic materials on priming effect of organic carbon in arable black soils
LI Na, TENG Peiji, LEI Wanying, LONG Jinghong, LI Lujun
, Available online  , doi: 10.12357/cjea.20230234
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The addition of exogenous organic matter (EOM) affects the mineralization and stabilization of soil organic carbon (SOC) via priming effects (PE). However, few studies have considered the effects of different EOM additions on PE in the same soil type with a gradient in SOC content. The underlying mechanisms have rarely been revealed, and related studies can provide in-depth insights into the microbial mechanisms that regulate carbon accumulation and stability in agricultural soils. It is crucial to predict dynamic changes in SOC and carbon pool stability in response to EOM inputs from different sources. Therefore, this study focused on topsoil with four SOC contents, which ranged from 10 g·kg−1 to nearly 70 g·kg−1, in the typical black-soil region of Northeast China, and aimed to investigate the effects and microbial mechanisms involving different types of EOM addition on PEs by adding 13C-labeled maize straw, glucose, and alanine to the soil. Compared to a control treatment without EOM, the addition of EOM promoted the mineralization of SOC in the four soils with different SOC contents. Specifically, glucose, alanine, and straw addition increased the cumulative mineralization of SOC by 50.88%–419.65%, 69.54%–409.48%, and 13.14%–321.43%, respectively. The addition of the three types of EOM also induced a positive PE in soils with different SOC contents. During the initial 30 days of incubation, the cumulative PEs in soils with different SOC contents under glucose and alanine addition treatments were considerably higher than those under straw addition treatment. Soils with higher SOC content exhibited greater cumulative mineralization and PEs with the addition of glucose and alanine, whereas their relative cumulative PEs were lower. SOC mineralization and PEs decreased and reached a stable state with incubation time in soils with different SOC contents. Fourier-Transform Infrared spectroscopy revealed a slight increase in the relative peak area of aliphatic carbon functional group and a slight decrease in the peak area of aromatic carbon group in soils with different contents of SOC after addition of EOM. The effects of SOC content on aliphatic and aromatic carbon functional groups were greater than those of the EOM type. Correlation analysis revealed that cumulative SOC mineralization and PEs were significantly positively correlated with total phospholipid fatty acids, biomass of total bacteria, gram-positive bacteria, gram-negative bacteria, and actinomycetes, with a peak area of aliphatic carbon at 1420 cm−1 (P<0.05). In addition, cumulative SOC mineralization and cumulative PEs were significantly negatively correlated with the biomass of fungi and anaerobic bacteria, with a peak area of aromatic carbon at 1630 cm−1 (P<0.05). Structural equation modeling indicated that the positive PE resulting from EOM addition was primarily influenced by bacterial and actinomycete phospholipid fatty acids in the soil, regardless of the SOC content of the four soil samples. These results demonstrated that EOM addition significantly increased the growth and metabolism of k-type microorganisms, such as gram-negative bacteria and actinomycetes, in arable black soil and promoted the decomposition of recalcitrant components in SOC. The “co-metabolism” theory, namely the co-decomposition of EOM and SOC, is considered as the primary mechanism behind the positive PE in black soil.
Crop yield prediction in Ethiopia based on machine learning under future climate scenarios
Xu Ning, Li Fadong, Zhang Qiuying, Ai Zhipin, Leng Peifang, Shu Wang, Tian Chao, Li Zhao, Chen Gang, Qiao Yunfeng
, Available online  , doi: 10.12357/cjea.20230257
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Crop yield and agricultural development are the foundation of human survival. In Ethiopia, where agriculture is the economic backbone, food supply and security are crucial for national security and people's livelihoods. Crop yield is greatly influenced by climatic conditions, but the coupling relationship between them has not been clearly explained, which poses difficulties for quantitatively analyzing crop yields under climate change. The development of machine learning techniques provides a method for predicting changes in such complex systems. This study predicts the changes in the yield of five major staple crops in Ethiopia from 2021 to 2050 by using machine learning methods combined with climate predictions from Global Climate Models (GCMs) under different future scenarios in the Sixth Coupled Model Intercomparison Project (CMIP6). First, data on 9 climate variables from 37 GCMs under four scenarios (historical, SSP1-2.6, SSP2-4.5 and SSP5-5.8) in CMIP6 were obtained. A Taylor diagram was used to select the best-performing GCMs and calculate their weighted averages. These averages were combined with five soil indicators to form an independent variable database. After removing highly correlated variables using Spearman's correlation coefficient, machine learning models were trained using 10 yield data variables of teff, maize, wheat, barley and sorghum for two major growing seasons in Ethiopia from 1995 to 2020 as dependent variables. This paper employed Histogram Gradient Boosting (HGB), Extreme Gradient Boosting Random Forest (XGBRF), Light Gradient Boosting Machine (LGBM), Random Forest (RF), Extra Trees (ET) and K-Neighbors as machine learning models. After model evaluation, the top-performing three models were stacked using linear regression. The independent variables were input into the final model to predict the yields of the 10 staple crops in Ethiopia from 2021 to 2050. The results were analyzed, and the following conclusions were drawn. (1) CMCC-CM2-SR5, MPI-ESM1-2-LR, EC-Earth3-Veg-LR, EC-Earth3-Veg and MPI-ESM1-2-HR obtained higher overall scores in the Taylor diagram analysis, indicating better simulation of climate in Ethiopian compared to other GCMs. (2) The Correlation coefficient (R2), Mean absolute error (MAE), and Explained variance score (EVS) of the XGBRF, RF and ET were higher than those of HGB, LGBM and K-neighbors. The stacking method of ensemble learning improved the performance of the ensemble model over individual models. (3) Over the next 30 years, the changes in crop yield during the Meher season (the longer growing season in Ethiopia, which is generally from April to December) were mainly within 2 t·hm−2. In the Belg season (the shorter growing season in Ethiopia, which is generally from February to September), there was a greater decrease in yield under SSP126 scenario, while the other two scenarios showed an increase, possibly due to the mitigation of greenhouse effects reducing the fertilization effect of CO2. (4) With intensification of social conflicts and environmental degradation caused by human activities, there is a growing need in the research area to change the agricultural structure and redistribute productivity, and this leads to the transfer of agricultural productivity to new suitable areas. Under SSP126 and SSP585 scenarios, the research area will achieve higher crop productivity due to the alleviation of drought conditions and the exacerbation of greenhouse effects, respectively. The results of this study demonstrate the changes in crop yield in the research area under different future climate change scenarios, providing references for determining agricultural production potential and formulating agricultural policies in the research area.
Difference of response thresholds between leaf gas exchange and yield to drought for spring wheat
ZHAO Funian, LIU Jiang, ZHANG Qiang, WANG Runyuan, WANG Heling, ZHANG Kai, ZHAO Hong, QI Yue, CHEN Fei
, Available online  , doi: 10.12357/cjea.20230223
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Leaf gas exchange is the basis for crop biomass and yield formation. During the development of drought, leaf gas exchange exhibits a threshold response to water stress, and many related physiological indicators are based on this response to monitor drought severity for crops. However, the focus of agricultural production is crop yield, and it is not clear whether the response threshold of leaf gas exchange indicators used to monitor drought is synchronous with the response threshold of crop yield to drought. This to some extent affects the accuracy of monitoring agricultural drought using physiological indicators related to leaf gas exchange. In this study, based on drying down experiments, the changes in leaf gas exchange for spring wheat during drought development process were observed and analyzed. The response threshold of leaf gas exchange for spring wheat to drought was determined, and this threshold was used to parameterize the crop model for spring wheat. Then, drought stress simulation experiments were designed to analyze the response threshold characteristics of spring wheat yield to drought and the differences with the threshold of leaf gas exchange. The results showed that the response threshold of stomatal conductance for spring wheat to soil available water content was 0.50, which was higher than the response threshold of transpiration rate and net photosynthetic rate (0.40). By parameterizing the crop model for spring wheat with the response threshold of net photosynthetic rate to soil available water content, the aboveground biomass and yield of spring wheat were simulated. It was found that the model simulation values explained more than 70% of the observed variation, and the statistical test was highly significant (P<0.01). The relative root mean square error between the model simulation values and the observed values was less than 30%, indicating a high overall simulation accuracy of the model. The consistency index was greater than 0.85, and the relationship slope between the simulation values and the observed values was between 1.00 and 1.50. This indicates that the crop model used in this study could accurately simulate the changes in aboveground biomass and yield for spring wheat. Using the validated model, the study analyzed the formation process of spring wheat soil moisture, leaf area index, aboveground biomass, and yield under different drought stress scenarios. It was found that the response threshold of aboveground biomass and yield of spring wheat to available soil water content was 0.18, which was significantly lower than the response threshold of leaf gas exchange indicators. The research results demonstrate that using physiological indicators such as leaf gas exchange during the crop growth period to characterize drought severity and reflect the degree of crop yield reduction may have certain issues. When using physiological indicators such as leaf gas exchange obtained during the crop growth period to characterize drought severity, it might overlook the crop's own drought resistance characteristics and the impact of drought duration on crop yield, which can lead to an overestimation of the severity of crop drought and an underestimation of the crop final yield. The results of this study can provide a reference basis for agricultural drought monitoring, prediction, and drought impact assessment.
Effects of long-term application of organic fertilizer on soil available phosphorus content and leaching risk in greenhouse tomato cultivation
SUN Delong, WANG Ying, ZHOU Jun, FU Ruitong, ZHANG Yuling, YU Na, ZOU Hongtao
, Available online  , doi: 10.12357/cjea.20230076
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To explore the soil available phosphorus content and leaching risk of long-term application of organic fertilizer under greenhouse tomato cultivation, to provide an important reference for rational fertilization in greenhouse tomato cultivation. Based on the field experiment of located fertilization in greenhouse tomato cultivation for 8 years, five treatments were selected: no fertilization (CK), single application of chemical fertilizer (NPK), and combined application of low, medium and high amounts of organic fertilizer and chemical fertilizer (M1NPK, M2NPK, M3NPK). The contents and profile distribution of soil total phosphorus (Total-P), available phosphorus (Olsen-P) and soluble phosphorus (CaCl2-P) in each fertilization treatment were studied. The changes of soil phosphorus environmental threshold and agriculture threshold with profile distribution, and the appropriate phosphorus application amount in greenhouse tomato cultivation were analyzed. The results showed that the contents of Total-P, Olsen-P and CaCl2-P in all treatments were decreased gradually with the increase of soil depth in 0-50 cm soil layer, and their contents in 0-10 cm soil layer were significantly higher than those in 30-50 cm soil layer (P<0.05). Compared with CK, Total-P, Olsen-P and CaCl2-P contents increased in all fertilizer treatments and increased with the amount of organic fertilizer applied, and the effect of medium (M2) and high (M3) organic fertilizer application on Total-P, Olsen-P and CaCl2-P contents in the 0-20 cm soil layer was significant (P<0.05).In 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm and 40-50 cm soil layers, the environmental threshold of soil phosphorus increased first and then decreased with the increase of soil depth, which were 139.6 mg·kg−1, 152.4 mg·kg−1, 133.5 mg·kg−1, 86.1 mg·kg−1 and 42.3 mg·kg−1, respectively. In 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm soil layers, the agriculture threshold of soil phosphorus decreased gradually with the increase of soil depth, which were 185.1 mg·kg−1, 120.5 mg·kg−1, 92.8 mg·kg−1 and 56.0 mg kg−1, respectively. Taking the soil Olsen-P content corresponding to the soil phosphorus agriculture threshold as the risk assessment criterion of phosphorus leaching, through the relationship between soil Olsen-P content and phosphorus application rate (P2O5), it was inferred that the suitable amount of phosphorus (P2O5) for greenhouse tomato cultivation was 344.9−530.3 kg hm−2, and the amount of P2O5 supplied by organic fertilizer was 119.9−305.3 kg ·hm−2. Under the condition of located fertilization in greenhouse tomato cultivation for 8 years, on the basis of chemical nitrogen, phosphorus and potassium fertilizers (N 375 kg∙hm−2, P2O5 225 kg∙hm−2 and K2O 450 kg∙hm−2), the application of low amount of organic fertilizer (15 000 kg hm−2) could not only improve the soil available phosphorus content of 0-20 cm, and significantly increase the tomato yield, but also effectively control the risk of soil phosphorus leaching.
Research on the differences in the perceptions of farmers in the tea culture landscape genes of agricultural heritage sites: a case study of the Chaozhou Dancong Tea culture system
CHENG Jiaxin, SUN Yehong, CHANG Yu
, Available online  , doi: 10.12357/cjea.20230166
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Agricultural heritage is a living heritage with important social, economic and ecological values and distinctive cultural landscape features. Identifying the cultural landscape genes of agricultural heritage has positive significance. In the existing research results related to landscape genes, most of the traditional settlements and historical architectural neighbourhoods are studied from the perspective of landscape genes. The number of analyses and research results on landscape genetic characteristics of agricultural heritage sites is very few, and this study can fill the gaps of landscape genetic research on agricultural heritage sites in the domestic academic field, which is a complementary and perfect research on landscape genetics and dynamic conservation of agricultural heritage. Based on landscape gene theory and local theory, the Chaozhou Dancong Tea cultural system is used as an example to identify the landscape genes, and farmers are used as research subjects to explore the intrinsic link between tea cultural landscape genes and farmers’ perceptions, and to explore the differences in the perceptions of different livelihood types of farmers on the evolution of tea cultural landscape genes. The three dimensions of ecological genes, production genes and living genes constitute the landscape genes of the Chaozhou Dancong Tea culture system. Combined with the questionnaire surveys and in-depth interviews with local farmers, the data were analyzed with the help of the related software SPSSAU, and the local farmers’ perception of the changes in the landscape genes of the tea culture was finally obtained. The results show that: 1) farmers perceive significant changes in the ecosystem, living environment, farming tools and techniques and lifestyle of the tea plantations and villages in the last decade. 2) Farmers in high mountain tea growing areas perceive environmental changes in the mountains, tea plantations and villages more strongly, and farmers in low mountain tea growing areas perceive changes in cultivation techniques and knowledge more strongly. 3) Farmers with different livelihood strategies showed significant differences in their perceptions of the genetics of the tea culture landscape, with farmers of a single type of tea perceiving indicators such as ‘changes in the area of hills and terraces’ more strongly. 4) There are differences in the perception of ecological genetics of the tea culture landscape among farmers with different total tea revenue. Farmers in high altitude tea areas, with single livelihood strategies and higher tea incomes had a stronger perception of genetic changes in tea culture landscapes and a higher awareness of ecological conservation, but a low degree of livelihood diversification and farmers are exposed to higher shocks from market risks, natural disasters and other external risks. Farmers in low mountain tea areas, diverse livelihood strategies and lower tea incomes had poorer awareness of ecological conservation and weaker perception of genetic changes in ecological landscapes. However, ecosystems and land resources, as natural capital, are important components of the livelihood capital of farmers, and ecological vulnerability can lead to vulnerability of farmers’ livelihoods. Ways to enhance the resilience of the livelihoods of different types of farmers can be proposed to raise their awareness of ecological protection and heritage inheritance, and to provide ideas for the sustainable development of agricultural heritage sites.
Evaluation of the accuracy of soil moisture sensors in typical soils in the Hebei Plain
ZHANG Qikun, MIN Leilei, WANG Yucai, ZHU Yiding, JIA Minglei, SUN Kaiwen, SHEN Yanjun
, Available online  , doi: 10.12357/cjea.20230179
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Soil moisture is one of the essential factors for the growth of crops and plants, and the measurement of soil moisture is the basis of research on agriculture, hydrology, environment and soil and water conservation. Compared with the traditional methods of soil moisture measurement, the main measurement methods at present are to use different types of soil moisture sensors. The research on soil moisture sensors is mostly based on the comparative study of foreign soil, and the research on the adaptability of sensors manufactured by foreign manufacturers in domestic soil is less; The factors considered in previous studies are usually limited to soil temperature, soil salinity and soil texture types, and fewer texture types are considered, so there is a lack of research on more factors and more soil texture types. An in-depth understanding of the performance of different types of soil sensors is of great significance in improving the accuracy of regional soil water content measurement. Therefore, in order to explore the measurement performance of different types of sensors in typical soils of the Hebei Plain, five kinds of soil moisture sensors widely used at home and abroad were selected in this study, and the influence of soil texture and bulk density on their measurement accuracy was mainly investigated. Four typical soil textures (silty clay, silt loam, sandy loam and sand) were selected to study the accuracy of five common soil moisture sensors (TDR315H、CS655、5TE、Teros12、Hydra Probe II) under different bulk density conditions (5 bulk density, 1.40 g·cm−3、1.45 g·cm−3、1.50 g·cm−3、1.55 g·cm−3、1.60 g·cm−3, respectively). The results show that: 1) under the experimental conditions, the measurement accuracy of uncalibrated TDR315H、CS655、Teros12 and Hydra Probe II is higher, the measurement error is less than 0.03cm3 ·cm-3, and the performance of TDR315H is the best; 2) generally speaking, the errors of five types of sensors in coarser soil are greater than those in finer soil, and the influence of soil texture on the measurement accuracy of sensors is far greater than that of soil bulk density; 3) the soil moisture content also has a significant impact on the accuracy of the sensor. With the change in soil moisture content, the measurement error also changes, and there may be a threshold of soil moisture content (such as 0.3 cm3∙cm−3 in this study) that makes the measurement accuracy of the sensor change significantly. In general, without calibration, TDR315H is expected to be directly applied in the field measurement of soil water content in agricultural land in Hebei Plain. This study can provide an important reference for sensor selection in soil moisture monitoring.
Effects of nitrogen application on physiological characteristics and nitrogen uptake and utilization of watermelon under chloride stress
WANG Xina, LIU Xue, LI Xuefang, WANG Xiangyin, TAN Junli
, Available online  , doi: 10.12357/cjea.20230162
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Chloride stress is one of the main factors limiting the yield and quality of watermelon in Ningxia due to long-term irrigation with underground chlorinated brackish water, while nitrogen could alleviate the chlorine toxicity of crops, so it is very important to explore the regulation mechanism of nitrogen on chloride stress of watermelon for applying nitrogen fertilizer rationally and controlling chlorosis of watermelon under chloride stress. In this paper, soil culture experiment was carried out to study effects of different nitrogen application levels [0, 0.10, 0.15, 0.20, 0.25 g kg−1(oven-dry soil)] on anion-cation balance, organic osmotic regulators, antioxidant enzyme activity, oxidative damage and nitrogen uptake and utilization in watermelon seedlings under chloride stress of 160 mg Cl−1∙kg−1 (oven-dry soil) with the test crop of watermelon of Jincheng No.5 variety. Results showed that nitrogen application considerably reduced Cl- and Na+ contents in roots, stems and leaves of watermelon, while significantly increased NO3− and K+ contents at P<0.05, thus the ratio of Cl−/NO3− and Na+/K+ of the whole plant both decreased by 45.7−68.7% and 31.3~54.2% compared with that of 0 g∙kg−1 N level, respectively. Moreover, the contents of soluble sugar and proline, superoxide dismutase (SOD) and catalase (CAT) in leaves reached the maximum levels at 0.15 g∙kg−1 N level, which statistically increased by 75.5%, 44.2%, 55.82% and 54.9% at P<0.05 compared with that of 0 g∙kg−1 N level, respectively, while the content of malondialdehyde (MDA) significantly lowered by 43.30%. Moreover, when nitrogen was applied 0.15 g∙kg−1, the nitrogen accumulation of watermelon increased by 95.3%, the activity of nitrate reductase (NR) enhanced by 78.7%, and the nitrogen uptake efficiency and nitrogen use efficiency went up 26.3% and 97.1%, respectively, and thus the fresh weight and dry weight of plant differently increased by 96.9% and 73.9% at P<0.05. Cluster analysis and correlation analysis of nitrogen application rate and physiological growth indexes of watermelon showed that mitigation effect of nitrogen application on watermelon chloride stress was 0.15 g∙kg−1>0.20 g∙kg−1>0.10 g∙kg−1>0.25 g∙kg−1, there were significantly positively correlation among biomass and dry matter accumulation to nitrogen uptake and utilization efficiency, and nitrogen accumulation, while there were also significant positive correlations between nitrogen accumulation with antioxidant enzyme activity and osmo-modulator content, but negatively correlated with Na+/K+ ratio, Cl−/NO3− ratio and MDA content. Based on the curve fitting results of each index, the nitrogen application rate of 0.14−0.18 g/kg was available for the growth and physiological activity of watermelon when the chloride concentration was 160 mg Cl−1∙kg−1 (dry soil). It indicates that appropriate nitrogen application under chloride salt stress can maintain ion homeostasis in plants by adjusting the Na+/K+ ratio and Cl−/NO3− ratio, and improve the content of osmoregulatory substances and antioxidant enzyme activities, thereby reducing cell membrane oxidative damage, enhancing the physiological resistance of watermelon plants, and achieving the regulatory effect on chloride stress.
Research progress on the regulation mechanism of crop roots on the production and emission of N2O in rhizosphere soil
Yuming Zhang, Li Xing, Xiaoxin Li, Qin Shuping, Yannan Li, Jian Han, Chunsheng Hu
, Available online  , doi: 10.12357/cjea.20230368
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Agricultural land has been pointed as a major source of N2O. N2O emission is not only affected by agricultural management measures,but also closely related to the growth of crop roots. Root self-metabolism affects the formation and reduction of N2O in rhizosphere soil, and then affects N2O emission from farmland. The rhizosphere is an important interface of root-soil-microbial interaction, and it is the most direct and intense key place where roots affect soil N2O emission. It is also the hot spot area of soil N2O production in farmland, and its share in farmland N2O emission cannot ignored. Therefore, the mechanism of root influence on rhizosphere N2O emission has been widely paid attention to.N2O Based on relevant researches, this paper comprehensively reviewed the research progress on the intensity of influence of crop root growth on N2O emission in farmland soil, and the regulatory mechanism of N2O production and emission in rhizosphere microdomain, Analyzed the existing difficulties in the research on the influence of crop root growth on N2O production and emission in rhizosphere microdomain soil. The future related research work is also prospected. The effect of root system on N2O emission in farmland is complicated and involves many factors. A large number of studies have shown that factors such as fertilizer application amount and fertilizer type, soil nitrogen content level and form, temperature and humidity, and light intensity can affect water and nutrients extracted from soil, The conduction and secretion of photosynthetic products to roots by regulating root growth, and change rhizosphere microdomain aeration status and nutrients such as carbon and nitrogen sources that microorganisms depend on for survival. Furthermore, the community structure, quantity and activity of rhizosphere microorganisms as well as their distribution in soil are affected, which mediates the nitrification and denitrification processes of rhizosphere microorganisms, and affects the generation, reduction and emission of N2O in rhizosphere soil. In view of the influence of many factors, crop root growth can promote or inhibit the production and emission of soil N2O, and the direction and strength of its effect will affect the overall emission budget of N2O in farmland ecosystem. Therefore, it is imperative to study the regulatory effect of crop roots on soil N2O emission and its feedback mechanism on global warming, which is of great significance to reduce the uncertainty of global N2O emission prediction and mitigate the impact of human activities on global change.
, Available online  
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Nutrient flow characteristics analysis of typical county in crop-livestock systems in Black Soil Region in Northeast China
WANG Yiying, ZHANG Chang, YUAN Jingchao, LIU Jianzhao, WANG Naihui, LIANG Yao, FAN Wei, REN Jun, CAI Hongguang
, Available online  , doi: 10.12357/cjea.20220938
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The integration of crop and livestock production promotes agricultural green development under the guarantee of food security in Black Soil Region in Northeast China. In this study, Nong’an County, Jilin Province, located in Black Soil Region in Northeast China, was selected as the study boundary. Quantitative studies for nitrogen and phosphorus flows, utilization efficiency as well as environmental losses in crop-livestock systems from 1990 to 2020 were conducted through field research, statistical data and literature, combined with the NUFER model (NUtrient flows in Food chains, Environment and Resources use). Explore the driving role of climate and socio-economic factors on nitrogen and phosphorus emissions. Furthermore, two scenarios of balanced fertilization (reduce fertilizer application) and organic substitution (increase organic material substitution) were set up to assess the county’s emission reduction potential. The results showed that, compared to 1990, nitrogen and phosphorus inputs to crop-livestock systems for Nong’an County in 2020 decreased by 41% and 20%, respectively, with chemical fertilizer application as the largest input. The nutrient utilization efficiency of crop system and crop-livestock systems increased fluctuatingly, while nutrient utilization efficiency of livestock system decreased and tended to remain stable. The nitrogen and phosphorus losses of crop-livestock systems decreased by 41% and increased by 29% compared to 1990, respectively. Ammonia volatilization from farmland, runoff and erosion, and livestock manure discharge as the major emission routes. Through balanced fertilization and organic substitution, it is predicted that by 2030, Nong’an County will have the potential to reduce the application of chemical nitrogen fertilizer by 70% to 80% and chemical phosphorus fertilizer by 80% to 85%, based on the low levels of soil nitrogen and phosphorus accumulation, and the environmental emissions will be reduced by 67%, the nutrient utilization efficiency of crop system and crop-livestock systems will increase by more than 50%. In conclusion, Nong’an County has a high application of chemical fertilizer and a significant waste of organic materials in crop-livestock systems, which resulted in a low level of nutrient utilization and high environmental emissions. In the future, increasing the potential of fertilizer application reduction is considerable by increasing the amount of crop straw and manure returned to the field. The Black Soil Region in Northeast China should continue to deepen the policy of zero grow in fertilizer, and promote the resource utilization of organic waste to guarantee a synergistically optimized crop-livestock systems.
Study on Spatiotemporal Changes of Physiological and Biochemical Indexes and Total Flavonoids of Tetrastigmahemsleyanum in response to blue and purple monochromatic light treatment
, Available online  , doi: 10.12357/cjea.20210116
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, Available online  
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