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Climate-smart agriculture research: hotspots, trends, and prospects
PAN Youju, XU Yuting, YU Ran, XU Guoliang, ZHOU Yan, LI Yingni
 doi: 10.12357/cjea.20220467
Abstract(67) HTML(43) PDF(19)
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Climate-smart agriculture (CSA), a high-potential agricultural system solution to the dual challenges of climate change and food security, received great attention from researchers worldwide as soon as it was proposed. However, the progress of CSA research projects in China is slow and has not attracted widespread attention from the academic community. Using the CiteSpace (5.8. R3) software, this study selected the core data set of the Web of Science to analyze the international CSA research literatures from 2010 to 2021, sorted out foreign research hotspots and trends, and put forward new outlooks to provide theoretical and practical support for the development of CSA in China. The research results were as follows: 1) CSA had formed a complete conceptual framework for balancing agriculture and climate change in multiple dimensions. 2) CSA and sustainable intensification, smart agriculture (smart farming), conservation agriculture, and other researches were intertwined and developed, and research hotspots revolved around “three pillars”: productivity, adaptation, and mitigation. 3) The trend of CSA research tended to be generalized, and the research areas covered developing countries, research objects focused on multiple goals, and research content covered multiple fields. Finally, according to future research trends, CSA was predicted to pay more attention to its connotation exploration, implementation framework formulation, vulnerable group needs, interdisciplinary cooperation, and agricultural transformation. In addition, this study emphasizes that as a new model of agricultural development in response to climate change, the theoretical framework and practical technologies of CSA have both theoretical and practical significance for agricultural transformation in China, and its application and adaptive development in China is an area that needs to be urgently investigated.
Research progress on regulation of root nodule formation and development of legume by light signals and photosynthetic products
LI Yiling, CHEN Ping, FU Zhidan, LUO Kai, DU Qing, GAO Chao, REN Junbo, YANG Xueli, LIU Shanshan, YANG Lida, YUAN Xiaoting, PENG Xinyue, YONG Taiwen, YANG Wenyu
 doi: 10.12357/cjea.20220415
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Legumes coexist with rhizobia to form nodules to meet plant nitrogen requirements through symbiotic nitrogen fixation. Legume nitrogen fixation capacity is of great significance to reduce nitrogen fertilizer consumption and potential environmental pollution and achieve sustainable development of agricultural production. The symbiotic nitrogen fixation of legumes consumes a large amount of energy; therefore, the energy supply of plants regulates the process of symbiosis and nitrogen fixation. This study reviews the recent research progress on the control of root nodule formation and development by light through plant photomorphogenesis and photosynthesis. Plant leaves sense blue light signals through blue light receptors (CRY1b) and produce light receptor-dependent transcription factors (STFs/FTs) to move from ground to ground. In addition, they integrate root hair development and the rhizobia-induced symbiotic signal (NIN) pathway to form root nodules. The movement and attachment ability of rhizobia in the environment are stimulated by light. In the symbiosis between plants and rhizobia, plants exchange photosynthetic products to produce NH4+, which is assimilated by rhizobia. In addition, photosynthetic products (sucrose) are transported to root nodules through the phloem for a long distance and are metabolized into organic acids through glycolysis and other pathways in root nodules, providing a carbon skeleton, energy, and reductant for nitrogen fixation of rhizobia. The intermediate metabolites of photosynthates, such as glucose, glucose-6-phosphate, and trehalose 6-phosphate, combine with the regulatory proteins of glucose signal metabolism proteins TOR and SnRK1 to initiate the complex growth and development pathway of nodule cortex cells. Under low-nitrogen conditions, photosynthates are also secreted into the rhizosphere in the form of flavonoids and organic acids, recruiting rhizobia to form symbiotic relationships with plants.
Effects of returning gramineous green manure to cotton field on soil carbon and nitrogen in saline alkali soil
WANG Jingkuan, GAO Fengshu, ZHANG Kaiyue, LI Shuai, LIU Xinwei
 doi: 10.12357/cjea.20220221
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To explore the effect of gramineous green manure on soil carbon and nitrogen contents in saline alkali cotton fields, two low-temperature- and saline alkali-tolerant gramineous green manures, ryegrass ‘Dongmu 70’ and barley ‘Zhudamai No.4’ were selected for in situ returning experiments from 2018 to 2019. Three treatments were set up: winter fallow farmland–cotton (T1), ryegrass–cotton (T2), and barley–cotton (T3). The contents of soil organic carbon (SOC), soil total nitrogen (TN), soil microbial biomass carbon (SMBC), and soil microbial biomass nitrogen (SMBN) were measured in different treatments at different periods (15, 50, 110, and 180 d) after returning green manure to field. The soil microbial quotient (SMQ) and ratio of soil microbial biomass carbon to nitrogen (SMBC/SMBN) were calculated. The results showed that both T2 and T3 significantly increased the contents of SOC and TN, and reached maximum values of 9.50 g∙kg−1 and 798.84 mg∙kg−1 (T2) and 9.91g∙kg−1 and 759.34 mg∙kg−1 (T3) at 180 d after returning green manure, respectively, and they were significantly higher than those of T1 treatment by 29.60% and 27.85% (T2) and 35.20% and 25.13% (T3), respectively. The variation dynamics of SMBC and SMBN contents in T2 and T3 were basically similar throughout the returning period, indicating a trend of stable growth in the early stage and significantly higher contents than those in T1, and a decrease in the latter stage and slightly lower contents than those in T1 at 110 d. The maximum values of SMBC and SMBN were 217.84 mg∙kg−1 and 34.51 mg∙kg−1 for T2, and 212.88 mg∙kg−1 and 33.43 mg∙kg−1 for T3 at 50 d and were higher than T1 by 81.46% and 47.76%, and 77.33% and 43.13%, respectively. In addition, the contents of SMBC and SMBN at different periods after returning to the field demonstrated that T2 was higher than T3. The change trend in SMQ in different treatments was consistent with that of SMBC. The two green manure treatments showed higher SMQ except for 110 d. T2 reached a maximum value of 2.82% at 15 d, while T3 reached a maximum value of 2.98% at 50 d. The SMBC/SMBN values of each treatment varied from 4 to 7; therefore, the microbial community in the soil was concluded to be mainly bacteria after returning the green manure to the field. T2 and T3 showed higher SMBC/SMBN values compared with T1, except at 110 d. In conclusion, the planting and return to the field of gramineous green manure in winter fallow farmland in saline alkali soil can significantly improve soil carbon and nitrogen contents in cotton fields, ameliorate the composition of soil microbial communities, improve the effect of soil microbial carbon sequestration, and provide nutrients for the growth of subsequent crops. The research results have guiding significance for the rational utilization of winter fallow farmlands in saline-alkali soils.
Effects of salt stress on physiological characteristics and yield of different salt-tolerant wheat varieties
TAO Rongrong, LU Yu, YU Qi, MA Quan, DING Yonggang, QIAN Jin, DING Jinfeng, LI Chunyan, ZHU Xinkai, GUO Wenshan, ZHU Min
 doi: 10.12357/cjea.20220164
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Soil salinity is a global issue that affects wheat production, and it is of great interest to improve the production efficiency of wheat in saline fields. A comprehensive understanding of salt-tolerance mechanisms and the selection of reliable screening indices are crucial for breeding salt-tolerant wheat cultivars. Previous studies have reported the performance of wheat under salt stress and controlled experimental conditions, such as potted plants, seawater (saltwater) irrigation, hydroponics, and salt ponds, but could not simulate the actual production environment in the field and reflect the law of crop growth in a natural state. How salinity stress affects wheat yield, and the physiological indicators that contribute to yield formation under saline field conditions are not yet to be established. Five spring wheat varieties with significant differences in salt tolerance (salt-tolerant varieties: ‘NM21’ ‘YM20’ ‘YFM4’; salt-sensitive varieties: ‘YM23’ ‘AN1124’) screened in a previous experiment were grown at two sites with significantly different soil salinity, namely: non-saline (control, soil salinity before sowing was 0.770±0.062 g∙kg−1) and saline (soil salinity before sowing was 3.294±0.198 g∙kg−1) fields, in Dafeng, Jiangsu, China. The yield and its components, post-anthesis chlorophyll content, chlorophyll fluorescence Fv/Fm, malondialdehyde content, and proline content were measured. The results showed that the leaf area index, dry matter accumulation, and tillers number decreased significantly in saline field. Moreover, compared with the control, wheat yield in saline field decreased significantly and was only 26.2% of the control. The number of spikes, kernels per spike, and 1000-grain weight also decreased significantly. The number of spikes, which decreased by 60.7%, was the main constraint on yield production, followed by the 1000-grain weight, which also decreased. Salt stress also caused a significant decrease in chlorophyll relative content (SPAD value) and chlorophyll fluorescence Fv/Fm but significantly increased the malondialdehyde and proline contents; the range of change differed among varieties. Salt-tolerant varieties had a lower decrease in chlorophyll content and chlorophyll fluorescence Fv/Fm and a lower increase in malondialdehyde content but a higher increase in proline content, therefore, there was a lower decrease in yield. Correlation analysis was carried out for the physiological characteristics at the flowering stage, yield, and its constituent factors in wheat with different salt tolerances. The results showed that there was a significant positive correlation between chlorophyll fluorescence Fv/Fm and the number of spikes, 1000-grain weight, and yield, and SPAD value was positively correlated with dry matter accumulation. A significant positive correlation was observed between dry matter accumulation and the number of spikes, 1000-grain weight, and yield, indicating that salt stress inhibits photosynthesis in wheat by reducing chlorophyll content and chlorophyll fluorescence Fv/Fm, reducing the production of photosynthetic products, consequently resulting in a final yield reduction. Hence, in field identification, SPAD value and chlorophyll fluorescence Fv/Fm at the flowering stage can be used as fast and reliable indices for salt tolerance in wheat. Furthermore, ‘YM20’ had the lowest yield reduction rate and better overall performance, making it suitable for planting in Dafeng saline land.
Characteristic evolution and influencing factors of the spatial correlation network of agricultural green total factor productivity in China
TAN Rihui, LIU Huimin
 doi: 10.12357/cjea.20220339
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Improving agricultural green total factor productivity (AGTFP) is essential to the development of green agriculture. Few researches has evaluated the characteristics and influencing factors of the spatial correlation network of AGTFP, which is not conducive to the development of green agriculture. Therefore, based on relational data and networks, using data from 31 provinces (cities and autonomous regions) in China from 2010 to 2019, this study used the SBM-Undesirable model to determine AGTFP, and adopted the social network analysis method to analyze the overall structure and individual characteristics of the spatial correlation network of AGTFP. The dynamic process of factors affecting the spatial correlation network of AGTFP was analyzed through a quadratic assignment procedure (QAP) model. The results revealed that: First, the AGTFP in China showed an upward trend as a whole, and the average value increased from 0.47 in 2010 to 0.85 in 2019 with scope for improvement and high regional variability. In addition, the spatial correlation effect of AGTFP of provinces (cities and autonomous regions) exceeded geographical proximity, forming a complex spatial correlation network throughout the country. Second, the correlation and stability of the spatial correlation network of AGTFP were reinforced during the study period. From 2010 to 2019, the number of network relationships increased from 124 to 215, and the network density increased from 0.13 to 0.23. Meanwhile, the network level reduced from 0.53 to 0.29, and the network efficiency reduced from 0.84 to 0.67. Third, the centrality of the spatial correlation network of AGTFP in China fluctuated in different years. The eastern region, relying on a more developed economy, had become the main factor gathering place in the spatial correlation network; therefore, it had a high central degrees. While parts of the western region had a very high central degree due to the inflow of factors from the central and eastern regions mainly through policy support. A few areas in the central region haf a very high central degree due to their superior location. Finally, the results of this study demonstrated that the effects of influencing factors on the spatial correlation networks of AGTFP in China varied from year to year, and the level of economic development, agricultural development, informatization, transportation improvement, and spatial adjacency had a marked impact on the formation of the spatial correlation networks of AGTFP in China. Therefore, the characteristics and influencing factors of AGTFP should be considered, and effective measures should be taken to enhance the spatial correlation of AGTFP.
Research progress in soil health regulation technology for protected agriculture
GENG Wencong, MA Yue, ZHANG Yuxue, ZHU Feng
 doi: 10.12357/cjea.20220349
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Soil health has become a limiting factor in the development of modern protected agriculture. Understanding the importance and underlying regulatory mechanisms of soil health and designing approaches towards healthy soil management are important guidelines for improving soil productivity and sustainable development in facility agriculture. In this article, the connotations of soil health in protected agriculture and its evaluation indicators are summarized. Furthermore, this paper reports existing problems, such as a high replanting index, continuous crop obstacle, and soil-borne diseases that may restrict healthy soil management. Next, we discuss techniques that are based on crop and soil regulation to improve soil health, including optimizing planting structures, cultivating resistant varieties, regulating nutrients, building artificial microbial communities, and regulating soil food webs. Finally, this article suggests that a soil health evaluation system for facility agriculture should be constructed, and new regulatory techniques should be introduced to provide a reference for more in-depth research on soil health improvement for protected agriculture.
Leaf senescence characteristics post-anthesis at different positions of spring maize canopy under different cultivation models
WANG Dan, LYU Yanjie, YAO Fanyun, XU Wenhua, CHEN Shuaimin, SHAO Xiwen, CAO Yujun, WANG Yongjun
 doi: 10.12357/cjea.20220291
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Post-silking is a critical period for maize yields. This study aimed to elucidate the senescence characteristics of spring maize leaves at different parts of the canopy under different cultivation modes, to understand the mechanism of yield formation and provide a theoretical basis for the regulation of senescence of maize plants in different cultivation models. Four cultivation modes with different agronomic measures were set up by integrating planting density, tillage method, and fertilizer management; they included inherent soil production (ISP), farmer household model (FP), high-yield and high-efficiency model (HH), and super-high-yield model (SH). The leaf area dynamic change model y=aebcx/(1+eb−cx) was used to analyze the senescence process of leaves, and photosynthetic pigment and antioxidant enzymes activities were measured in different parts of the leaves to compare the senescence characteristics of maize leaves under different cultivation modes. The yields of HH (12 445.55 kg∙hm−2) and SH (13 759.07 kg∙hm−2) were significantly higher than that of FP and ISP; they increased by 14.4% and 26.4%, respectively (P<0.05), compared with that of FP. The dry matter weight of SH increased by 18.5% and 10.4% compared with that of HH at silking and maturity stages (P<0.05), respectively, and that of HH increased by 2.8% (P>0.05) and 17.7% (P<0.05) compared with that of FP, respectively. Compared with FP, HH and SH started senescence later and the upper leaves were the most typical, with an average decrease in senescence rate of 26.7% and 18.0%, respectively (P<0.05). Compared with FP, the times to maximum reduction rate of relative green leaf area of HH and SH increased by 12 d and 8 d, and the maximum leaf area per plant increased by 8.7% and 6.6%, respectively (P<0.05). From 0 to 60 d after silking, the average leaf areas of lower canopy of HH and SH were 42.4% and 17.3% higher than that of FP, respectively (P<0.05). The photosynthetic pigment contents and protective enzymes activities of the lower and middle leaves of HH and SH plants were significantly higher than those of FP plants after silking. The activities of protective enzymes in the HH middle and lower leaves remained at a high level and decreased slowly during late growth period. After silking, the MDA content of all parts of the maize leaves in different cultivation modes tended to increase, and the MDA content of HH and SH remained at a lower level than that of FP. Compared with FP, for HH and SH with the integration of dense planting, deep tillage, and split fertilizer application technology, the leaf senescence started later in the upper part of the canopy during the flowering period, but the leaf area in the middle and lower parts showed higher and slower senescence. In addition, after silking, the pigment content was very high and decreased slowly, and the leaf protective enzyme activity was very high; this significantly slowed down the senescence process of middle and lower leaves and was conducive to photosynthesis assimilation and high yield.
Effects of phosphorus application and rhizobial inoculation on nitrogen and phosphorus uptake in soybean||maize intercropping systems in different soil types
WANG Qianqian, LIU Zhiqiang, CHEN Kang, WANG Xiurong
 doi: 10.12357/cjea.20220124
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A pot experiment was conducted to compare the effects of rhizobial inoculation on growth, nitrogen (N) and phosphorus (P) uptake, and rhizosphere chemical properties of soybean [Glycine max (L.) Merr.] and maize (Zea mays L.) intercropping systems with different P fertilizer applications in both acidic and calcareous soils, to provide a reference for the field application of rhizobial inoculants. The pot experiment with ‘BX10’ soybean variety and ‘Zhengtian 68’ maize variety as experimental materials adopted a three-factor experimental design, including factor A, P levels [with P fertilizer (+P) and without P fertilizer (–P)]; factor B, two soil pH types (acid soils form Ningxi and Wengyuan, and calcareous soils form Sanping and Changping); and factor C, two inoculation treatments [with rhizobial inoculation (+Ri) or without rhizobial inoculation (–Ri)]. The nodule traits of soybean, plant dry weight, total N and P uptake, and related rhizosphere traits of soybean and maize were determined at the pod stage of soybean. The results showed that inoculation with rhizobia increased the total N uptake of the intercropped soybean under P application in acidic soil, and inoculation with rhizobia improved nodule traits and increased total N uptake of the intercropped soybean regardless of P application and promoted total P uptake of the intercropped soybean in calcareous soil. In both calcareous soils, the total P uptake of the inoculated soybean plants increased significantly. In the calcareous soil of Sanping, the rhizosphere pH was significantly reduced and the rhizosphere acid phosphatase activity of the inoculated soybean significantly increased after rhizobial inoculation and P application. In the calcareous soil of Changping, the rhizosphere alkaline phosphatase activities of intercropped soybean and maize significantly increased after inoculation with rhizobia under P application. With increased total N and P uptake, rhizobial inoculation increased the plant dry weight of intercropped soybean in calcareous soil but had no effect on plant dry weight and total N and P uptake of intercropped maize. In conclusion, soil pH and P availability significantly influenced the effectiveness of rhizobial inoculation. In acidic soil, inoculation with rhizobia increased the total N uptake of intercropped soybean under P application. In calcareous soil, inoculation with rhizobia could promote the synergistic effects of N and P and further promote the growth of intercropped soybean. The promotion of P mobilization and acquisition by rhizobial inoculation might be attributed to the enhancement of rhizosphere processes in calcareous soil.
Plant mediated interaction between aboveground and underground herbivores under drought stress
SHU Yuan, JU Jing, ZHAO Haitao, HAO Yanbin, LI Linfeng
 doi: 10.12357/cjea.20220140
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With global climate change, the frequency and intensity of drought events may increase. Therefore, it is crucial to predict the net impact of global climate change on ecosystems by studying the interaction between aboveground and underground phytophagous insects mediated by plants under drought stress. Based on the findings from an extensive literature review, we found that: 1) The interaction between aboveground and underground phytophagous insects in recent climate is mainly based on the “plant stress hypothesis” and “defense induction hypothesis” and the interaction between aboveground and underground phytophagous insects is affected by the order of phytophagous insects arriving at the host plant, performance parameters of phytophagous insects, life history of plants, and types of phytophagous insects. 2) The effect of drought stress on plants is based on the hypothesis of “growth differentiation” which has been corroborated to some extent. 3) Drought stress can cause changes in plant physiology, thereby affecting the relationship between plants and aboveground leaf-eating insects (chewing insects, stinging insects). 4) Few studies have examined the interaction between plants and underground root-eating insects under drought stress. At present, few studies suggest that the damage to plant roots caused by drought and underground root-eating insects may be superimposed. 5) The interaction between aboveground and underground phytophagous insects mediated by plants under drought stress may be affected by phytophagous insect species; plant species; type, concentration, and distribution of plant defense compounds; plant hormones; plant palatability; plant communities; and habitats. 6) In the future, research on plant-mediated aboveground and underground phytophagous insect interactions under drought stress needs to further reduce experimental limitations, for example, long-term field experiments, expanding the scope of experiments (including more plants and phytophagous insect species), innovative experimental methods, and evaluation of the dominant mechanism between interactions.
Simulation of response of sugarcane growth to meteorological drought scenarios based on Aqua Crop model in Nanning
YANG Yunchuan, CHENG Yuhao, LIANG Liqing, LIAO Liping, WANG Tingyan, ZHANG Huiya, YANG Xingxing, HU Jiaqiu
 doi: 10.12357/cjea.20220315
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Rain-fed sugarcane is mainly cultivated in Nanning, an area with extensive hills and karst. The soil water deficit caused by meteorological drought is a major factor affecting sugarcane growth and yield in this region. The cane yield has experienced huge losses due to drought over the years. Therefore, the daily standardized weighted average precipitation index (SWAP) was calculated using 0.1° grid daily meteorological data from 1979−2018, and the meteorological drought characteristics and possible drought event scenarios during the sugarcane growth period were identified. Finally, the Aqua Crop model was employed to simulate and reveal the mechanisms of sugarcane growth, biomass, and yield accumulation in response to meteorological droughts of multiple intensities and durations. The results showed that the duration, intensity, and frequency of meteorological drought presented significant spatial heterogeneity in Nanning, and meteorological drought events mainly occurred during the sugarcane growth stages of sprouting, stem elongation, and maturity. In addition, seasonal droughts with durations longer than 30 days and sudden droughts with durations less than 30 days occured alternately in the study area. The Aqua Crop model showed good simulation accuracy with the yield determination coefficient (R2) reaching 0.92, and the root mean square error as 3.84%, which were achieved after the sensitivity analysis by the Extended Fourier Amplitude Test (EFAST) and the crop parameter localization for the model. That is, the Aqua Crop model had good simulation accuracy and practical value in this study. The simulation results of a typical meteorological drought year demonstrated that the cane yield (Y) and biomass accumulation (B) were sensitive to meteorological drought of all intensities. However, transpiration (Tr) was sensitive to meteorological drought only during the tilling and stem elongation stages, and canopy coverage (CC) appears to have a significant lag effect in response to meteorological drought. The variation in the above four factors showed an obvious response when the meteorological drought lasted for 15 days or more during the sprouting stage. Nevertheless, the variation in the above four factors appeared to be a significant response when the meteorological drought lasted for only 5 days or more during the stem elongation stage. There was no significant response of the above four factors to meteorological drought for all intensities and durations in the maturity stage. In terms of different meteorological drought intensity scenarios, the reduction rate variations of cane yield (Yw), biomass (Bw) and transpiration (Trw) were, respectively, 0−24.0%, 0−18.5%, and 0−15.9% when the duration of light drought increased from 5 to 35 days; 25.0%−37.0%, 20.0%−29.3%, and 8.0%−24.4% when the duration of moderate drought increased from 15 to 45 days; and 33.5%−40.0%, 26.2%−31.7%, and 18.9%−25.7% when the duration of severe drought increased from 35 to 50 days. These results reveal the quantitative mapping relationship between sugarcane growth process, cane yield accumulation, and meteorological drought for all intensities and durations in the study area, which plays an important scientific supporting role in the chain transmission mechanism analysis of sugarcane drought among meteorological drought, soil moisture, and sugarcane growth, in multi-stage drought early warning systems, and in the intelligent management of drought dynamic risk.
Effects of all straw return on root secretions of wheat in different seasons
WU Yu, CAI Hongmei, XU Bo, YU Min, WANG Pengna, DAI Wenci, ZHANG Mengxiang, REN Yi, WU Wenming, LI Jincai, CHEN Xiang
 doi: 10.12357/cjea.20220199
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Root exudates play an important role in the exchange of substances and chemicals between plants and soil. Different straw returning modes change the growth environment of wheat roots, and wheat root exudates have different response characteristics to different straw returning modes. Screening for a suitable straw returning mode is a key issue for sustainable and high-quality development of wheat production. Metabolomics of root exudates can potentially help us to better understand the chemical interaction between roots, soils, and organisms in the rhizosphere. In this study, to investigate the effects of all straw return in different seasons of winter wheat-summer maize rotation system on wheat root exudates in the lime concretion black soil area in Huaibei Plain, four straw returning modes were developed, they included all wheat straw smashed mulching in summer maize season (T1), all wheat straw smashed mulching in summer maize season + all maize straw crushed burying in winter wheat season (T2), all maize straw crushed burying in winter wheat season (T3) and no straw returned to field (CK). The metabolomics of wheat root exudates collected under different straw returning modes was investigated based on non-targeted metabolomics combined with liquid chromatography-mass spectrometry. Multivariate statistical analysis methods were used to quantify the differences in metabolomics among different straw returning modes. The results showed that T1 treatment increased the root length and root dry weight of wheat during the overwintering period and resulted in higher root vigor compared to other treatments. T1, T2, and T3 detected 330, 110, and 89 differential metabolites compared with CK, respectively. Compared with CK, the relative contents of some oligosaccharides, such as stachyose and verbascose, in the root exudates of T1 increased, and the galactose metabolism and glycolytic pathways were greatly affected. The relative contents of proline, valine, isoleucine, glutamic acid, and glutamine of T1 increased, and the metabolism of arginine and proline, and D-glutamine and D-glutamate metabolism were affected greatly. The relative contents of 3-hydroxysebanoic acid, creatine phosphate, 3-isopropenylglutaric acid, 4-heptanoic acid, and cinnamic acid of T1 increased. The results indicated that all wheat straw smashed mulching changed the characteristics of wheat root exudates; increased the root length and dry weight of wheat by increasing the relative content of some sugars, amino acids, and organic acids; and maintained high root vitality under the condition of straw return. Metabolomic analysis of root exudates based on non-targeted metabolomics combined with liquid chromatography-mass spectrometry could provide an important theoretical basis for the study of the efficient utilization of straw resources and high yield, high quality, and high-efficiency development of wheat production in the lime concretion black soil area in Huaibei Plain.
Government promotion, social networks and farmers’ adoption behavior of ecological farming technology
WEI Binbin, YANG Zhihai
 doi: 10.12357/cjea.20220305
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The application of ecological farming technology is significant to ensure national food and ecological security, but the adoption rate at farmer level is still low. To explore the role of government promotion and social networks in improving the application of ecological farming technology, this study used Ordered Probit and Tobit models and a sample of 787 farmers from six major grain-producing provinces to empirically investigate the impacts of government promotion and social networks on farmers’ behavior of using ecological farming technology. This study contributes to the literature on the adoption of agricultural technology in two ways. First, we evaluated and compared the effects of government promotion and social networks on the adoption of ecological farming technology. Particularly, we investigated the moderating effects of heterogeneous social networks on government promotion, which is helpful in utilizing different channels of technology extension. Second, considering farmers’ use of ecological farming technology has changed from self-providing to outsourcing, we estimated the impacts of government promotion and social networks on farmers’ preferences for the outsourcing adoption of ecological farming technology. The main findings were as follows: First, although the direct impact of government promotion on farmers’ adoption of ecological farming technology was not significant, government promotion had a significant and positive impact on farmers’ adoption of ecological farming technology under the moderating effect of kinship networks. Second, government promotion had a significant and negative impact on farmers’ adoption of ecological farming technology, that is, it was not conducive for farmers to adopt ecological farming technology through outsourcing. However, relationship networks, especially kinship network, significantly weakened the negative effect of government promotion. Third, social networks played an important role in promoting farmers’ adoption of ecological farming technology. Whether it was the kinship or general network, it had a positive impact on farmers’ adoption of ecological farming technology, encouraging farmers to adopt the outsourcing of relevant technologies. However, the influence of the kinship network was greater than that of the general network. Based on the above findings, this study suggests that it is important to consider the heterogeneous and complementary effects of different social networks when promoting the adoption of ecological farming technology at the farmer level. In addition, it is helpful to use socialized services in agricultural production to promote ecological farming technology.
Transcriptome analysis of copper resistance in Lysobacter soli strian RCu6
LI Fuyu, CHEN Shuaimin, LIU Mengshuai, CHEN Miaomiao, LI Xiaofang, LIU Binbin
 doi: 10.12357/cjea.20220198
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Copper is a trace element that has essential functions in many cellular enzymes; however, excessive copper levels can be toxic. Bacteria have evolved several copper resistance strategies, but the underlying mechanisms are not yet fully understood. Elucidating the mechanisms of copper resistance in bacteria is important for developing microbe-based techniques for mitigation of heavy metal pollution. In this study, a highly copper-resistant (resistant to copper concentrations up to 3.2 mmol∙L−1) bacterial strain RCu6 was isolated. The genomic characteristics of RCu6 were studied using whole-genome sequencing, and copper resistance mechanisms were analyzed using transcriptome analysis. Whole-genome sequencing of strain RCu6 indicated that it belonged to Lysobacter soli. Compared to other strains in the same genus, this strain has a unique DNA fragment encompassing cop, cus, czc, and other homologous copper resistance genes. Transcriptome analysis showed that 315 (239 up-regulated and 76 down-regulated) and 839 (449 up-regulated and 390 down-regulated) genes were differentially expressed under 0.8 mmol∙L−1 and 1.6 mmol∙L−1 copper concentrations, respectively. The differential gene expression was mainly associated with copper homeostasis, histidine metabolism, sulfur metabolism, and iron-sulfur cluster assembly metabolism, indicating that these processes may play important roles in copper resistance of RCu6. The results of the transcriptome analysis were further verified using qPCR. The expression levels of 12 randomly selected genes associated with copper resistance showed significant correlations between qPCR and RNA-Seq data (R2=0.84 for GAPDH gene and R2=0.98 for 16S rRNA gene as internal reference genes). Therefore, the genomic and transcriptome results suggest that copper resistance in the strain Lysobacter soli RCu6 is an intracellular multi-system collaborative process. This study provides new information for understanding the complex regulatory network of copper homeostasis in prokaryotes. It also provides bacterial resources and a theoretical basis for the remediation of heavy metals in farmland soil.
Ecological development of agricultural engineering with the background of rural revitalization: ecological agricultural engineering
WEI Xiuju, LIAO Yan, ZHU Ming
 doi: 10.12357/cjea.20220400
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Rural revitalization is a strategic goal of the overall, comprehensive, integrated, and coordinated development of agricultural and rural areas in the new era. In the context of rural revitalization, China’s agricultural engineering needs to further innovate and expand to meet the needs of agricultural and rural area development in the new stage. Ecological agricultural engineering is a cross-discipline of agricultural engineering and agricultural ecological engineering. Focusing on ecological agricultural engineering, this research analyzed its concept and connotation and discussed the importance, future development prospects, development direction, and existing problems under the background of rural revitalization. Ecological agricultural engineering is the ecological development of agricultural engineering, which comprehensively promotes the ecological thought of traditional agricultural engineering in terms of development ideas and connotations, and expands the ecological field of agricultural engineering. Given the great demand for rural revitalization, development of ecological agricultural engineering has been proposed. Ecological agricultural engineering is a technical means to realize ecological agriculture, which can meet the developmental needs of rural revitalization, ensure the sustainable productivity of agricultural ecosystems, and promote the sustainable development of agriculture and rural areas. Ecological agricultural engineering can be regarded as a cross-discipline of ecological engineering and agricultural engineering. The importance of developing ecological agricultural engineering is mainly reflected as follows: promoting the construction of ecological civilization; supporting the high-quality development of rural industry, systematic and all-round rural revitalization; and promoting the sustainable development of agricultural and rural areas. In the future, Ecological agricultural engineering can provide an important guarantee for food security, and it is an important measure to alleviate the energy crisis, an effective path to the construction of beautiful villages, and a way to achieve prosperity. This can enrich and expand the discipline connotation of agricultural engineering to meet the needs of the new situation of rural revitalization, so it has broad developmental prospects. The development of ecological agricultural engineering will play a major role in promoting rural revitalization in China in the field of ecological development of agricultural engineering.
Funding, implementation and outcomes research projects in farmland chemical and biological pollution of the National Key Research and Development Program of China in the 13th Five-Year Plan period
XU Changchun, LIU Jie, XIONG Wei
 doi: 10.12357/cjea.20220823
Abstract(58) HTML(19) PDF(15)
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Chemical and biological pollution in farmland is a new area for agricultural ecology and environmental research both in China and abroad. Based on project management work, the authors summarized application submission, peer review, and grant funding processes; analyzed research outcomes; and briefly introduced major research results concerning the two research projects in the chemically and biologically polluted farmland funded by the National Key Research and Development Program of China in the 13th Five-Year Plan period. Through funding and implementation of the projects, a number of achievements have been made in basic research, technical development, and application. With this paper, we aim to provide references for related academics and policy makers and boost future research in the area of farmland chemical and biological pollution.
Factors influencing electricity-to-water conversion metering method for irrigation water consumption in Hebei Plain
LI Fei, TAO Peng, QI Yongqing, LI Hongjun, WANG Hongxi, WANG Ning, PEI Hongwei, ZHANG Xiying
 doi: 10.12357/cjea.20220288
Abstract(60) HTML(31) PDF(10)
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Regional grain production in the Hebei Plain relies on groundwater irrigation to maintain high and stable yields. However, numerous irrigating wells are scattered, making it difficult to obtain reliable groundwater abstraction for agricultural irrigation. The electricity-to-water conversion method is an indirect measurement of groundwater pumping. The use of electric energy consumption as a proxy offers a solution to the problems of maintenance and acceptance, as electricity is usually metered for fee collection and metering is well accepted. Moreover, it can be efficient and convenient in measuring groundwater abstraction for agricultural irrigation. Based on the electricity-to-water conversion factors of county-level agricultural irrigation and the monitoring results of groundwater depth, this study analyzed the regional characteristics of the electricity-to-water conversion factor and the correlation between groundwater depth and the conversion factor in the Hebei Plain. The Luancheng Agro-Ecosystem Experimental Station of the Chinese Academy of Sciences, as a typical site, was selected for the irrigation experiment to study the relationship between electricity consumption and groundwater abstraction and analyze the influence of time consumption, irrigation method, and seasonal variation of the electricity-to-water conversion factor. We found that: 1) Under the same depth of groundwater level, the electricity-to-water conversion factors in the piedmont region were higher than those in the mid-eastern region of the Hebei Plain, and with a declining water table, the electricity-to-water conversion factor decreased. For every 10 m decrease in the water table, the electricity-to-water conversion factor of the deep aquifer in the piedmont and mid-eastern regions decreased by 0.42 m3∙kWh−1 and 0.15 m3∙kWh−1, respectively. 2) The results of the irrigation experiment showed that the relationship between electricity consumption and groundwater abstraction was relatively stable, and the fluctuation range of the electricity-to-water conversion factor between different times consuming for one irrigation was 5.7%. The irrigation season from early March to mid-June was affected by the seasonal variation of the groundwater level, and the seasonal variation of the electricity-to-water conversion factor was approximately ±10%. Different irrigation methods, such as pipe irrigation and sprinkler irrigation, had a significant impact on the actual conversion factor, and the efficiency of pipe irrigation was 28.8% higher than that of sprinkler irrigation. 3) The current county-level results for the electricity-to-water conversion factor in the Hebei Plain cannot support the requirements of farmers for irrigation metering, water rights, and water resource tax verification. Seasonal variations in groundwater level, irrigation methods, and non-irrigation electricity consumption should be considered to improve the metering accuracy of groundwater abstraction using electricity as a proxy.
Resource use efficiencies and economic benefits of winter wheat-summer maize cropping system with double mechanical grain harvest
ZHOU Baoyuan, CHEN Chuanyong, SUN Xuefang, GE Junzhu, DING Zaisong, MA Wei, WANG Xinbing, ZHAO Ming
 doi: 10.12357/cjea.20220279
Abstract(98) HTML(41) PDF(10)
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The evaluation of the mechanical grain harvest of winter wheat-summer maize cropping system and water-saving planting pattern of winter wheat without reduction in annual grain yield is an important way to improve the economic and ecological benefits of winter wheat-summer maize double cropping system in the Huang-Huai-Hai Plain. In this study, field experiments with the traditional winter wheat-summer maize cropping system (CK) and mechanically grain-harvested winter wheat-summer maize cropping systems (TR) were conducted at Jiaozhou of Shandong Province, Daming of Hebei Province, and Xinxiang of Henan Province from 2018 to 2020 to determine their annual yield, climate resource allocation and utilization, and economic benefits. The results showed that annual climate resources were redistributed through extremely late sowing (Mid November) of winter wheat and extremely late harvesting (Early November) of summer maize for TR, which affects the grain yield of wheat and maize. Compared with CK, TR decreased the grain yield of winter wheat by 9.2% across years and experimental sites owing to the reduction in biomass, spike number, and 1000-kernel weight. However, the yield of mid-late-maturing summer maize varieties in TR increased by 8.1% across years and experimental sites compared with that in CK, and the increase in kernel weight contributed to the yield increase in maize in TR. Moreover, there was no significant difference in the total biomass of summer maize between CK and TR, but the harvest index of summer maize in TR was higher than that in CK. Therefore, no significant difference in annual grain yield was found between TR and CK. The grain water content of summer maize at harvest for TR was between 14.1% and 16.8% and was significantly lower than that for CK. In addition, compared with CK, TR reduced water consumption during the winter wheat season and annual by 15.3% and 6.0% across years and experimental sites, respectively; but increased their WUE by 15.2% and 8.4%, respectively. Although the output and economic benefits of winter wheat under TR treatment reduced, the output and economic benefits of summer maize increased by 8.7% and 16.2% across years and experimental sites, respectively. As a result, the annual economic benefit of TR increased by 5.6% across years and experimental sites compared to that of CK. The results indicated that the establishment of doubl mechanical grain harvest of combined the extremely late sowing of winter wheat and extremely late harvesting of summer maize with mid-late maturity could help to achieve water-saving for winter wheat and mechanical grain harvesting of summer maize, ensuring a higher annual grain yield and economic benefit. This study provides ideas for improving the mechanization of winter wheat-summer maize double cropping system and the sustainable use of water resources.
Selection of high-temperature-resistant cotton cultivars based on physiological indexes and analysis of their relationship with root phenotypes
SI Peng, LIU Liantao, SUN Hongchun, ZHANG Ke, BAI Zhiying, LI Cundong, ZHANG Yongjiang
 doi: 10.12357/cjea.20220114
Abstract(57) HTML(26) PDF(12)
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In recent years, high temperatures have become an important abiotic stress factor that limits the growth and development of cotton in the Yellow River basin. The characteristics of different cotton cultivars in response to high temperatures, especially differences in root phenotypes, remain unclear. In this study, 15 cotton cultivars commonly cultivated in the Yellow River basin were cultured to the six-leaf stage in an artificial climate chamber under normal conditions (25 ℃ day/25 ℃ night), followed by treatments with control (25 ℃ day/25 ℃ night) and high (35 ℃ day/30 ℃ night) temperatures. Seven days later, 10 physiological indicators, including gas exchange parameters, chlorophyll fluorescence parameters, antioxidant system enzymes, and root phenotypic parameters, such as root length, root surface area, root volume, and average root diameter, were measured. The results showed that, compared with the control, for all cultivars, values of net photosynthetic rate, stomatal conductance, transpiration rate, PSⅡ maximum photochemical efficiency (Fv/Fm), and relative chlorophyll content (SPAD) generally decreased after high-temperature treatment; while activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), soluble sugar content, and relative conductivity increased. Ten indicators were integrated into two comprehensive indicators, and the high-temperature resistance coefficient and cultivar score for each cultivar were obtained using principal component analysis. Three high-temperature-resistant cultivars, ‘Shuofeng 1’ ‘Guoxin 9’ and ‘Lumianyan 28’; and five high-temperature-sensitive cultivars, ‘Shikang 126’ ‘Hanwu 216’ ‘Guoxin 4’ ‘Cangmian 268’ and ‘Nongda 601’, were screened out via cluster analysis. The correlation between the ratio of high temperature to control of root phenotypic indicators and the high-temperature tolerance score of high-temperature-resistant cultivars was further analyzed. The correlation coefficients of root length, root surface area, root volume, and mean root diameter were 0.766 (P<0.01), 0.659 (P<0.01), 0.628 (P<0.05), and 0.501 (P>0.05), respectively, indicating that root phenotypic parameters decreased less after high-temperature stress. Root length, surface area, and volume can also be used as indicators to screen cultivars resistant to high temperatures. This study provides theoretical and practical support for the selection and regulation of high-temperature-resistant cultivars.
Effects of Medicago sativa cultivation on soil denitrifying bacterial community in Loess Plateau
SUN Pengzhou, LUO Zhuzhu, LI Lingling, NIU Yining, WANG Xiaofei, TIAN Jianxia, LIU Jiahe
 doi: 10.12357/cjea.20220250
Abstract(35) HTML(20) PDF(3)
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Microorganisms with nitrite reductase genes can reduce nitrite to NO, which is an important influence in the biological nitrogen cycle. A field study was conducted to investigate soil denitrifying bacteria (nirK- and nirS-type) communities and diversity in a farmland (Zea mays field) and Medicago sativa land established based on different times (2, 9, and 18 years, respectively expressed as L2019, L2012 and L2003). Illumina MiSeq high-throughput sequencing and real-time fluorescent quantitative PCR technology were used to investigate the structure and diversity of denitrifying bacterial communities under four treatments (Farmland, L2003, L2012 and L2019). Redundancy analysis and molecular ecological network analysis were used to evaluate the relationship between soil physical and chemical properties and denitrifying bacterial community. The results indicated that the abundance of nirK gene was significantly higher than that of nirS gene. The abundance of nirK gene varied from 4.91×107 to 6.33×107 copies∙g−1, whereas the abundance of nirS gene varied from 1.02×107 to 1.86×107 copies∙g−1. The years of M. sativa cultivation did not affect the diversity of nirK- and nirS-type denitrifying bacteria. Proteobacteria had the highest abundance in the denitrifying bacterial community. The dominant genera of the nirK-type denitrifying bacteria were Paracoccus (1.10%–39.94%), Achromobacter (0.07%–12.50%), and Sinorhizobium (0.50%–7.60%). The relative abundance of Paracoccus in M. sativa soil was significantly higher than that in maize soil (P<0.05), and the relative abundance gradually increased with increasing age of M. sativa stands. The relative abundance of Achromobacter in M. sativa soil was significantly lower than that in maize soil (P<0.05), and the abundance decreased gradually with increasing age of the M. sativa stand. The dominant genus of nirS-type denitrifying bacteria was Rhodobacter (1.42%–5.20%). There was no significant difference in Rhodobacter abundance between the maize fields and M. sativa fields. Correlation analysis showed that the abundance of nirK-type denitrifying bacteria had no significant response to soil environmental factors, but the abundance of nirS-type denitrifying bacteria had a significant positive correlation with soil organic carbon (r=0.762), total nitrogen (r=0.776), and microbial biomass carbon (r=0.622) and a significant negative correlation with soil water (r=–0.678) and available phosphorus (r=–0.628). RDA analysis indicated that soil water (P=0.002) and organic carbon (P=0.020) were the main environmental factors affecting the community structure of nirK-type denitrifying bacteria, and soil available phosphorus (P=0.006) was the main environmental factor affecting the community structure of nirS-type denitrifying bacteria. The proportion of positively correlated edges in the nirK-type denitrifying bacterial ecological network was 98.37%, and the proportion of negatively correlated edges was 1.63%; however, all edges in the nirS-type denitrifying bacterial ecological network were positively correlated. This indicated that the relationship between bacterial communities of both types of denitrifying bacterial was mainly synergistic. In summary, long-term planting of M. sativa significantly affected the composition of soil denitrifying bacterial community. Our results provide a scientific basis for further studies on the microbial mechanism of denitrification in the Loess Plateau after years of M. sativa planting.
Effects of sowing date on yield performance and safe sowing date window of mechanically grain-harvested spring maize
RONG Meiren, GAO Julin, WANG Fugui, WANG Zhen, YU Xiaofang, SUN Jiying, HU Shuping, WANG Zhigang
 doi: 10.12357/cjea.20220202
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The selection and promotion of mechanically grain-harvested maize varieties pose new challenges to the full utilization of heat in northern spring maize regions. Under the background of climate warming, exploration of the potential of advancing the sowing date can provide a basis for making full use of regional heat resources and obtaining sufficient dehydration time for mechanically grain-harvested maize. In this study, suitable local grain-harvesting maize varieties were used as test materials. Experiments were carried out in six ecological regions of Inner Mongolia, which are the east region of Xing’an Mountain (EXM), south region of Xing’an Mountain (SXM), west Liao River Plain (WLR), north region of Yanshan Mountain (NYH), Tumote Plain (TMP), and Hetao Plain (HTP). The results showed that in the spring maize areas of six ecological regions of Inner Mongolia, maize was sown six to eight days ahead of the conventional sowing date for mechanical grain-harvesting, and the maize yield could be increased by 7.5%–18.4% under the optimal sowing date. The suitable sowing date window of each ecological region was different: EXM from May 4 to 11, SXM from April 27 to May 10, WLR from April 15 to 30, NYH from April 9 to 26, TMP from April 9 to 29, and HTP from April 3 to 22. With an increase in latitude, this period gradually became “narrower.” For every 1° increase in latitude, the average window period was shortened by 1.8 d, and the average advance of the sowing date was reduced by 2.8 d. The sowing date had no significant effect on the corn harvest index. At the “source” end, the development of pre-anthesis leaf area index, pre-anthesis photosynthetic potential of the mechanically grain-harvested maize population were promoted, which significantly increased the population biomass. At the “sink” end, the population sink activity and yield per plant were improved by increasing grains number per ear and 1000-grain weight. In Inner Mongolia, the yield of spring maize mechanically grain-harvested in the security window for suitable early sowing was increased by 10.4% through ascension of “source” development pre-silking, extension of the persistent period of leaf area, optimization of “sink” activities, improvement of the yield per plant and full use of the heat resource condition. Meantime, the mature seed dehydration occurred at an effective accumulated temperature of 43.7 ℃ to 130.9 ℃. This is beneficial for increasing yield and harvest quality of mechanically grain-harvested maize.
Agroecosystem and Its Management
Research progress and future directions of arbuscular mycorrhizal fungi-plant-rhizosphere microbial interaction
CHU Wei, GUO Xinlai, ZHANG Chen, ZHOU Liuting, WU Zeyan, LIN Wenxiong
2022, 30(11): 1709-1721.   doi: 10.12357/cjea.20220093
Abstract(462) HTML(95) PDF(139)
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Microecology of rhizosphere, a key area of soil ecology, affects plant growth and metabolism in many ways. Many scientists regard the root system as key to the second green revolution. Arbuscular mycorrhizal (AM) is one of the most common mycorrhizal symbiotic categories of plants and is closely related to the evolutionary history of terrestrial plants. Mycorrhizal symbionts formed by arbuscular mycorrhizal fungi (AMF) and host plant roots can change plant root morphology and improve nutritional status to promote the growth and development of host plants, improve stress resistance and disease resistance, participate in many physiological metabolic processes of plants, and indirectly affect plant growth through the regulation of soil structure and microbial community structure. This paper briefly describes the interaction between AMF and plants, rhizosphere microorganisms, and mycorrhizal helper bacteria (MHB); and discusses the important role of mycorrhizal symbiosis in plant establishment, competition, maintenance of biodiversity, and its role in the Earth’s ecology. Although the symbiosis between AMF and plants has shown good production benefits, most of the studies reported in the scientific literatures have been carried out under controlled conditions (growth chamber or greenhouse, sterile substrate). Because the response of AMF in the natural environment may differ significantly, it is also needed to evaluate the ability of AMF under field conditions. It is also very important to further explore the symbiotic gene network and key transcription factors in the molecular dialogue between plants and fungi, and decipher the key metabolic signaling pathway of MHB.
Temporal and spatial characteristics of nutrient flow and losses of the crop-livestock system in Baiyangdian Basin
YANG Wenbao, YANG Jing, ZHAO Zhanqing, ZHANG Jianjie, WEI Jing
2022, 30(11): 1722-1736.   doi: 10.12357/cjea.20220181
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The crop-livestock system in Baiyangdian Basin has changed significantly owing to the implementation of related policies and establishment of the Xiong’an New Area. Based on the NUFER (Nutrient flows in Food chains, Environment and Resources use) model and data from statistical year books, surveys, and literatures, this study determined the nitrogen and phosphorus requirements for crop-livestock systems and analyzed the temporal and spatial characteristics of nutrient use and environmental losses in Baiyangdian Basin on a county scale in the years 2005, 2015, and 2018. The results showed that the inputs of nitrogen and phosphorus fertilizers in Baiyangdian Basin in 2018 were far less than those in 2005 and 2015. For example, the input of nitrogen fertilizer in 2018 was 8.0% and 11.6% lower than that in 2005 and 2015, respectively. The nitrogen use rate of the crop system remained at approximately 44% throughout the study period, whereas the phosphorus use rate increased from 27.1% to 30.7%. The total nutrient input and manure nutrient losses decreased significantly in the livestock system, especially for the directly discharge pathway, whose nitrogen and phosphorus losses reduced to 24.7 Gg and 10.3 Gg, respectively in 2018, which were only approximately 37% of that in 2015. Nitrogen and phosphorus use rates increased significantly for the whole livestock system, reaching 23.3% and 18.6%, respectively in 2018. In 2018, the nitrogen and phosphorus inputs in the crop-livestock system were significantly lower than those in the previous two study years. However, the nitrogen and phosphorus use rates of the whole crop-livestock system first increased and then decreased during 2005–2018. Spatial analysis revealed that the nutrient input, output, and loss of the crop-livestock system were relatively lower in the eastern and western Baiyangdian Basin but higher in the middle areas compared to those in other areas. In conclusion, the goal of “zero increase” in fertilizer and optimization of manure management was achieved in Baiyangdian Basin, but the nutrient use rates of the crop-livestock system were still at a low level. There was an unbalanced development pattern of crop-livestock systems; some counties were characterized by high input, high loss, and low efficiency. In the future, the Baiyangdian Basin should deepen the policy of zero increase in fertilizer, continue to implement the action of recycling livestock waste, and distribute animals rationally to ensure a synergistically optimized crop-livestock system.
Analysis of spatio-temporal dynamics and driving forces of vegetation cover in the Hutuo River Basin based on the geographic detector
DING Yongkang, YE Ting, CHEN Kang
2022, 30(11): 1737-1749.   doi: 10.12357/cjea.20220309
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The Hutuo River Basin, located in the Shanxi and Hebei Provinces, plays an important role in regional ecological environment and urban development. Analysis of the spatio-temporal dynamics and driving forces of vegetation cover in the area provides an important scientific basis for sustainable social and economic development and ecological environmental protection. Based on the monthly scale MOD13Q1 (250 m) dataset for 21 years from 2000 to 2020, this study analyzed the spatio-temporal variation trend of vegetation using the unary linear regression method and discussed the correlation between temperature, precipitation, and NDVI using the Pearson correlation analysis method. Natural factors such as temperature, precipitation, vegetation type, soil type, and altitude, and human factors such as land use type, population density, and GDP were statistically divided using the geographic detector, and the degree of influence of each driving factor on NDVI was systematically discussed. Particularly in the case of the increasingly close relationship between vegetation cover and human activities, the driving force values of different human factors can be obtained quantitatively to provide a basis for future research and analysis of the influence mechanism of the main driving factors, ecological environment protection, and sustainable development of watershed. The results of this study were as follows: 1) In the past 21 years, vegetation cover in the area had been increasing, and the average NDVI and Slope index, which is used to indicate vegetation changing trend with the positive value meaning increase, from May to September every year were 0.71 and 0.0035, respectively. The vegetation restoration in the area improved slightly, with 81.00% of the area improving in NDVI and 10.08% of the area degrading. 2) There were positive correlations between NDVI and precipitation and temperature in the area, and the interannual variation in NDVI was more closely related to precipitation. The proportions of positive and negative correlation areas between precipitation and NDVI were 87.73% and 12.27%, respectively, among which 35.28% and 6.92% of the positive correlation area passed the significance test of P<0.05 and P<0.01, respectively. However, the NDVI in the surrounding areas of Yangquan and Shijiazhuang cities was negatively correlated with precipitation and temperature, which may be significantly affected by human activities. 3) The degree of influence of a single driving factor on NDVI in the area was ranked from high to low as follows: precipitation > temperature > land use type > vegetation type > soil type > population density > GDP > altitude. Among them, the q (showing impacting strength of factor) values of the first three factors were all greater than 0.3, and they were the main driving factors affecting the NDVI in the area. 4) The driving force of all the driving factors combined in pairs was significantly greater than that of a single driving factor, showing a two-factor enhancement effect. In addition, the interaction between land use type and precipitation, with a q value of 0.74, was the largest, and it was significantly greater than that of interactions between only human factors or only natural factors. In general, human activities have had a strong impact on the spatio-temporal pattern of vegetation cover, and comprehensive consideration of meteorological factors and rational planning of land use are key factors in improving vegetation cover in the area.
Crop Cultivation and Physiological Ecology
Research progress on photo-physiological mechanisms and characteristics of canopy microenvironment in the formation of intercropping advantages
FAN Hong, YIN Wen, CHAI Qiang
2022, 30(11): 1750-1761.   doi: 10.12357/cjea.20220660
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Intercropping is a production approach that can address the issues faced by modern agriculture, such as lowering green gas emissions and fossil material input, while also ensuring yields and system sustainability. The benefits of intercropping are primarily derived from the efficient use of time and space through interspecific interactions, formation of a root and canopy structure that is conducive to crop growth and resource efficiency, creation of an appropriate rhizosphere environment, and optimization of the physiological indicators of crop growth and development. Clarifying the photo-physiological mechanism of intercropping and its relationship with the canopy microenvironment will serve as crucial theoretical support for improving intercropping management technology and fully utilizing the advantages of intercropping. This study reviews the literatures on intercropping photosynthetic physiology at various levels, including populations, individuals, organs, cells, and molecules. Intercropping promotes the maintenance of photosynthetic sources and optimizes dry matter accumulation, distribution, and transportation at the population level; it increases the photosynthetic rate, chlorophyll content, and radiation use efficiency of tall crops but weakens the photosynthetic performance of short crops at the individual and organ levels. Additionally, the activities of phosphoenolpyruvate carboxykinase (PEPC) and Rubisco enzyme in tall crops are increased, whereas they are decreased in short crops; and intercropping tends to upregulate the expression of pepc and ppdk photosynthase genes in tall crops (maize) and upregulate genes encoding photoreaction centers in short crops (soybean). In terms of the intercropping canopy microenvironment, tall crops benefit from greater light interception and minimal temperature fluctuation. However, short crops experience deterioration in both light quantity and quality, lower canopy temperature, and higher humidity, which are unfavorable for crop growth. Regulatory approaches to promote the photo-physiology of intercropped crops and improve the canopy microenvironment include matching tall light-loving varieties and short shade-tolerant crop varieties, moderately increasing the row ratio of dwarf crops, and moderately increasing nitrogen and phosphorus fertilizers. Future research should explore the mechanisms at the microscale of intercropping using molecular biology techniques, discover growth laws and interspecies relationships of intercropping crops via growth model methods, breed special varieties to enhance interspecific interaction, and coordinate the spatial layout and group optimization theory appropriate for mechanization and interspecific interaction.
Eco-physiological mechanisms of silicon in alleviating the biotic and abiotic stresses in plants
QIAN Cheng, LI Xin’e, ZHAO Xin, LIU Dalin, WANG Lin
2022, 30(11): 1762-1773.   doi: 10.12357/cjea.20220112
Abstract(158) HTML(52) PDF(54)
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Owing to global climate change and human activity, abiotic and biotic stresses occur frequently, threatening crop yield and food safety. Reducing the effects of biotic and abiotic stresses is crucial for improving agricultural productivity. Silicon fertilizers are ecologically compatible and environmentally friendly. Silicon has been proven to alleviate plant stress under various conditions, indicating considerable application prospects. Systematic examination of the mitigation mechanisms of silicon on various abiotic and biotic stresses can provide guidance for future practice and research. In this review, we first introduced the absorption and deposition of silicon within plant organs, and the effect of silicon on the synthesis and metabolism of carbon-based substances (“Silicon-Carbon Trade-off Hypothesis”), and then summarized the eco-physiological alleviation mechanisms of abiotic stresses including osmotic stress, nutrient deficiency stress, heavy metal stress, extreme temperature, ultraviolet stress, and biotic stress. We concluded that the common mechanisms of silicon to improve plant stress resistance included improvement of anti-oxidation activities, enhancement of photosynthetic ability, and carbon-silicon trade-off; however, the mechanisms differed under different stresses. Furthermore, previous studies had mainly focused on the eco-physiological mechanisms of the effects of silicon, particularly on grass families such as rice, and the effects of silicon on carbon cycling in agricultural ecosystems had been largely ignored. Therefore, this paper concluded with an outlook on further studies on the molecular mechanisms of silicon, modifications of legume-rhizobia relationships, and significance of phytolith carbon sequestration in agricultural ecosystems. We aimed to provide help and references for broader and deeper investigations of silicon.
Effect of coated urea type and fertilization pattern on lodging resistance and yield of wheat following rice
MA Quan, QIAN Chencheng, JIA Wenxin, WU Yulei, LI Chunyan, DING Jinfeng, ZHU Min, GUO Wenshan, ZHU Xinkai
2022, 30(11): 1774-1783.   doi: 10.12357/cjea.20220195
Abstract(98) HTML(41) PDF(37)
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The purpose of this study was to investigate the effects of coated urea on the lodging resistance of wheat following rice and evaluate the rational application of coated urea to coordinate the yield and lodging resistance of wheat following rice. Resin-coated urea (PCU) and sulfur-coated urea (SCU) were used as the experimental materials, and three fertilization patterns were designed: 100% coated urea applied before sowing (N1); 60% coated urea applied before sowing and 40% urea at jointing (N2); and 60% coated urea applied before sowing and 40% coated urea at regreening stage (N3). A control (CK), with 60% urea applied before sowing and 40% at regreening stage, was also included. The differences in stem morphological characteristics, lodging resistance, and grain yield of wheat following rice under different coated urea and fertilization patterns were analyzed. The results showed that, compared with CK, N1 significantly decreased the length of the basal second internode; increased the fullness, diameter, and wall thickness of the basal second internode; and enhanced snapping resistance and lodging resistance index. The actual field lodging coefficients in PCUN1 and SCUN1 were only 1.11 and 1.31, respectively. The yield in PCUN1 and SCUN1 was low but was not significantly different from that of CK. N2 significantly decreased the fullness of the basal second internode and lodging resistance index but significantly increased the field lodging rate and lodging coefficient compared with N1. N3 achieved the highest yield, which was significantly higher than that of N1, N2, and CK for PCU and SCU. The field lodging rate and lodging coefficient in N3 were not significantly different from those in N2 but were significantly lower than those in CK. In N3, the yield in PCU was the highest; it increased by 14.75% compared with that in CK. The length of the basal second internode in PCUN3 was significantly lower than that in SCUN3; and the fullness, diameter, and wall thickness of the basal second internode were significantly higher than those in SCUN3. Moreover, the field lodging rate and lodging coefficient of PCUN3 were lower than those of SCUN3. In conclusion, 60% PCU applied before sowing and 40% PCU topdressing at re-greening can limit the length of basal second internode, improve fullness and snapping resistance, decrease lodging coefficient, and increase yield, and this is beneficial for coordinating the high yield and lodging resistance of wheat following rice.
Effects of soil water restriction on root growth and root morphology of perennial ryegrass and pasture brome
ZHANG Yongmei, HU Haiying, BAI Xiaoming, Matthew CORY, García-Favre JAVIER, Ordóñez IVÁN P
2022, 30(11): 1784-1794.   doi: 10.12357/cjea.20220336
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To study the adaptability of herb roots to drought environments, perennial ryegrass (Lolium perenne) and pasture brome (Bromus valdivianus) were supplied 80%–85% plant available water (PAW) and 20%–25% PAW in a pot experiment. By analyzing of root appearance, biomass accumulation, and root morphology of perennial ryegrass and pasture brome, an effective production strategy for the two forage grasses under extreme drought stress was explored. The results showed that the appearance of the root tips differed slightly between the two forage grasses. Pasture brome had long and dense root hair and a long elongation area in the root tips, whereas perennial ryegrass had sparse root hair and a short elongation area. Extreme drought stress (20%–25% PAW) resulted in uneven root thickness and malformation in perennial ryegrass. No obvious damage was observed in pasture brome roots. There was no significant difference between species and soil water content in terms of biomass accumulation and distribution in the shoots and roots of the two forage grasses. However, there were significant differences in root length, root area, root diameter, root tips, and root forks between the perennial ryegrass and pasture brome. The root quantity of perennial ryegrass was significantly higher than that of brome (P≤0.01); the root length and root area were approximately 1.5 times those of pasture brome; and the root tips and forks were more than twice those of pasture brome. Pasture brome roots were significantly thicker than perennial ryegrass roots, with root diameters of 0.315 mm and 0.259 mm, respectively. The lateral root branches of the pasture brome root were short, thick, and dense, whereas the lateral roots of the perennial ryegrass were long and thin. Drought stress significantly reduced the total root length of the two forage species and promoted the radial growth of roots in the pasture brome. In conclusion, pasture brome had a more developed root-hair-area, and perennial ryegrass had more root quantity. Therefore, perennial ryegrass is distinguished mainly by its root quantity and adopts an adaptive strategy of extensive water absorption, whereas pasture brome is distinguished by well-developed root hair, high lateral root branch density (quality), and adaptive strategies to ensure effective water absorption.
Interactive effects of drought and salt stresses on the growth and physiological characteristics of Thinopyrum ponticum
ZHANG Rui, FENG Xiaohui, WU Yujie, SUN Qi, LI Jing, LI Jingsong, LIU Xiaojing
2022, 30(11): 1795-1806.   doi: 10.12357/cjea.20220185
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Saline soils are mainly distributed in arid and semi-arid regions where both soil salt content and drought affect plant growth at the same time. Therefore, soil pot experiments were conducted to study the effects of soil salt content, drought, and their interactions on the growth and physiological characteristics of Thyropyrum ponticum seedlings to understand the adaptability of T. ponticum seedlings in saline soil areas and to provide a theoretical basis for the population establishment of T. ponticum in such areas. Twelve treatments, including four soil salinity levels (0, 4, 8, and 12 g∙kg−1 NaCl) and three soil moisture levels (75%–85%, 55%–65%, and 35%–45% of field capacity) were used. Shoot and root dry weights, leaf chlorophyll contents (SPAD values), leaf photosynthetic parameters, leaf antioxidant enzymes activities, and Na+ and K+ contents in shoots and roots were measured. The results showed that the growth of T. ponticum was significantly inhibited under drought stress or salt stress, whereas root/shoot ratios increased under the interactions of soil salt and drought stress, and the plants could still survive under 35%–45% field capacity with 12 g∙kg−1 NaCl. Drought and salt stress significantly reduced leaf chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate, whereas these parameters were increased under high salinity levels under moderate drought stress (55%–65% of field capacity) compared with those under normal irrigation. Moderate drought or salt stress increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), but these activities were decreased under 12 g∙kg−1 NaCl. The leaf malondialdehyde (MDA) content increased under extreme drought or salt stress. In terms of ion accumulation, Na+ and K+ contents, and K+/Na+ ratio were higher in shoots than in roots. Roots and shoots Na+ contents were increased with decreasing soil water content or increasing soil salinity, whereas K+ contents decreased but remained relatively high. Regarding salt-drought interactions, drought treatment could reduce salt stress in plants by promoting the accumulation of Na+ in roots. Under drought stress, root Na+ content was further increased by increasing soil salinity, while root K+/Na+ ratio remained stable and shoot K+/Na+ ratio was significantly decreased. The above results indicate that T. ponticum can survive under high drought and salt conditions, possibly due to its strong root system, higher root/shoot ratio, relatively complete antioxidant enzyme system, Na+ accumulation, and stable K+/Na+ ratio in roots. Although T. ponticum can survive under high drought and salt conditions, the high production of biomass still requires lower soil salinity and moderate drought conditions because the shoot biomass significantly decreases with the increase in soil salinity or decrease in soil moisture.
Community characteristics of nitrite-oxidizing bacteria in the rhizosphere of Fusarium wilt-diseased cucumber caused by continuous greenhouse cultivation
ZHENG Chenmeng, LIU Xing, ZHANG Ying, REN Xiujuan, CHEN Bihua, WANG Fei, SHEN Changwei, WU Dafu
2022, 30(11): 1807-1818.   doi: 10.12357/cjea.20220002
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Greenhouse cultivation is the most common method of vegetable production worldwide, and cucumber is one of the most important greenhouse vegetables. However, continuous cucumber cropping in intensive greenhouse production causes a high incidence of Fusarium wilt. It has been demonstrated that the occurrence of this disease was correlated with the alteration in plant rhizosphere microbiome. However, previous studies have focused on the overall microbial community (i.e., bacteria and fungi). The potential role of functional rhizosphere microorganisms in disease occurrence remains largely unclear. Nitrite oxidation (NO2 conversion to NO3), performed by nitrite-oxidizing bacteria (NOB), is a vital process in soil nitrification and therefore affects soil N availability and plant nitrogen uptake. In this study, we targeted greenhouse cucumbers subjected to continuous cropping by using rhizosphere soil samples from healthy plants (HPR) and Fusarium wilt-diseased plants (DPR), and assessed differences in their abundances and community diversities and structures of two major groups of NOB, Nitrobacter and Nitrospira, using real-time quantitative PCR and high-throughput amplicon sequencing. The results showed that there was no significant difference in the NO2-N content between DPR and HPR, whereas the potential nitrite oxidation rate (PNOR) in DPR was approximately twice as high as that of HPR (P<0.05). Nitrobacter abundance in the DPR was significantly higher than in the HPR (P<0.05), with no significant difference in Nitrospira abundance. Nitrobacter abundance was significantly and positively correlated with PNOR, suggesting that it dominated soil nitrite oxidation. For both Nitrobacter and Nitrospira, community diversity did not differ between the DPR and HPR, whereas significant differences in community structures were observed (P<0.05). Phylogenetic analyses revealed that the main members of the Nitrobacter community were Nitrobacter Cluster 3, Cluster 3-like, Cluster 2b, Cluster 4, Cluster 6, Cluster 1, and Cluster 5; in the Nitrospira community, Namibia soil Cluster 1, Cluster 2, Cluster 3, Nitrospira lineageⅠ, lineageⅡ, and lineageⅤ, respectively. In the Nitrobacter community, the average relative abundance of Nitrobacter Cluster 2b in HPR was significantly higher than that in DPR; and on the contrary for both Nitrobacter Cluster 6 and Nitrobacter Cluster 5. In the Nitrospira community, the average relative abundance of Namibia soil cluster 1 in the DPR significantly outnumbered that of the HPR by 92.19%, but the average relative abundance of Nitrospira lineageⅡ was far lower than that of the HPR. Redundancy analysis indicated that the NO2-N content was the most important soil physicochemical variable influencing the community structures of both Nitrobacter and Nitrospira. Among all the community members detected in this study, in terms of their average relative abundance, only Nitrobacter Cluster 6 was significantly positively linked with PNOR, suggesting that it may be an active member performing nitrite oxidation in continuously cropped greenhouse soil. Collectively, the present study confirmed that the occurrence of Fusarium wilt disease in greenhouse cucumbers in a continuous cropping system was accompanied by shifts in the community structure of NOB in the plant rhizosphere, which obviously affected nitrogen turnover in the diseased greenhouse soil.
Agricultural Resources and Environment
Effects of chloroform fumigation on soil organic carbon mineralization in purple soil farmland
MA Han, WANG Xiaoguo
2022, 30(11): 1819-1826.   doi: 10.12357/cjea.20220182
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In recent decades, mineralization of soil organic carbon has gradually become a focus due to greenhouse gas (GHG) emissions. The mineralization of soil organic carbon is mainly the decomposition of soil organic carbon under the action of microorganisms, which is an important pathway for soil organic carbon loss. Chloroform has strong sterilization power, and different microorganisms have different sensitivities to it. Furthermore, the soil microbial biomass and community composition can be changed by different fumigation durations. To explore the limiting factors of soil organic carbon mineralization in purple soil farmland, soils from plots with long-term application of pig manure treatment were selected for this laboratory incubation study. The effect of different soil microbial biomasses on soil organic carbon mineralization was investigated through varying the chloroform fumigation time and observing the changes in CO2 emission rate under different treatments. The experiment included five treatments: fumigation for 24 h (C24), 2.5 h (C2.5), 1.5 h (C1.5), and 1 h (C1); and an unfumigated control (CK). The treatment not only changed the soil microbial biomass, but also greatly changed the soil microorganism community composition, which further verified the Regulation Gate hypothesis. The results showed that after fumigation, the soil microbial residues released microbial biomass carbon and the remaining microorganisms rapidly utilized this carbon source. Due to the availability of this new carbon source, the soil CO2 emission rate increased rapidly. The variation trend in the soil CO2 emission rate among different treatments was consistent. Due to the microbial residue carbon source, the CO2 emission rate of fumigation treatment was higher than that of CK within 7 days of incubation, increasing rapidly to a maximum and then decreasing to a level comparable to the initial level. The order of the maximum values of the soil CO2 emission rate among different treatments was C2.5>C24>C1.5>C1>CK. Compared with CK, the increases were 309.01%, 182.00%, 73.85%, and 30.45%, respectively. There were significant differences among the treatments (P<0.05). The soil CO2 emission rate increased slowly and then decreased slowly during days 7–53 of the incubation. The average CO2 emission rates of treatments C24, C2.5, C1.5, C1, and CK were 6.01±0.43, 5.94±0.29, 6.07±0.59, 5.78±0.49, and 6.23±0.13 μg∙g−1∙h−1, respectively. After 32 d, the rates of fumigation treatments were slightly lower than that of CK with no significant differences among different treatments. The variation in cumulative CO2 emissions under different treatments conformed to the model y=atb. The higher the maximum emission rate, the smaller the value of a and the larger the value of b. The b value of all treatments was less than 1, indicating that the cumulative emission increased with incubation time with a gradually slowing rate. The results of this study support the Regulatory Gate hypothesis of soil organic carbon mineralization, which states that the mineralization of soil organic carbon is unrelated to microbial biomass size, community composition, and activity in calcareous purple soil farmland treated with pig manure over a long period of time.
Environmental risk and cost restraint mechanism for incorporating large quantities of vegetable residues into fields in semi-arid area of the Loess Plateau
ZHANG Guangquan, BA Yin, DU Yuming, LI Fengmin, XUE Wei
2022, 30(11): 1827-1841.   doi: 10.12357/cjea.20220435
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The incorporation of vegetable residues can fertilize low-quality loess, but it is still unclear whether large quantity of vegetable residues incorporation will cause secondary environmental pollution and increase processing costs. In this study, a plot test was designed in the semi-arid area of the Loess Plateau in Yuzhong, which was randomly combined with three thicknesses of incorporated vegetable residues (20, 40, and 60 cm), three thicknesses of surface soil covering (10, 20, and 30 cm). Meantime, two medium-scale site tests were conducted, in which the thickness of incorporated vegetable residue was up to 350 cm, and the surface soil covering thickness was 30 cm. The degradation rate of vegetable residues, emission rate of NH3 and H2S on the soil surface, residue of heavy metals and pesticides in the soil, salt ions contents, and processing cost were investigated. The cumulative degradation rate of vegetable residues in all treatments showed a logarithmic growth curve, which was first fast and then slow. On the 20th and 35th days, the degradation rate of vegetable residues reached 70.0% in the plot and the medium-scale test sites, respectively, and subsequently slowed down. When the thickness of the incorporated vegetable residues was 60 cm and the depth of covering soil was 10–30 cm, the emission of NH3 was reduced by 71.0%–86.0%, and the emission of H2S was reduced by 84.9%−87.9%, compared with QC (vegetable residue thickness of 60 cm and no soil cover). The time series changes of the NH3 emission rate on the soil surface showed a single narrow peak curve, and the peak value of emission rate and cumulative emission were significantly positively correlated with the thickness of incorporated vegetable residues, and significantly negatively correlated with the depth of the covering soil. There was no significant difference in H2S emissions from the soil surface of the plot test and QT (no incorporation of vegetable residues), and the H2S emissions from the medium-sized test increased significantly. The larger the amount of vegetable residues into the field, the smaller the emission intensity of pollutants was. There was no significant difference in the contents of heavy metals, pesticide residues, and Ca2+ in the vegetable residue layer and the upper and lower soil layers of the medium-sized test sites compared with those in QT (no incorporation of vegetable residues), whereas Na+ leached into the deep soil layer. There is a power-law negative correlation between the thickness of incorporated vegetable residues in the field and the processing cost in a medium-sized test field. The larger the incorporating capacity of vegetable residues, the lower the processing cost, and the lowest cost was 25.0 ¥∙t−1 (fresh weight). Therefore, in the semi-arid area of the Loess Plateau, using the method of covering soil and burying pressure to incorporate vegetable residues into the field in high quantities is a low-cost, simple, eco-friendly, and efficient processing scheme for utilizing vegetable residues.
Agricultural Ecologic Economics and Ecoagriculture
Research on influencing factors and prediction of agricultural carbon emission in Henan Province under the Carbon Peaking and Carbon Neutrality goal
GAO Chenxi, LU Qiuping, OU Nianqing, HU Qingping, LIN Xue, BAO Lingxin
2022, 30(11): 1842-1851.   doi: 10.12357/cjea.20220267
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Agricultural production is one of the main sources of carbon emissions, and agricultural carbon emission reduction is a key aspect for China to achieve Carbon Peaking and Carbon Neutrality goal. This study used the emission coefficient method to estimate agricultural carbon emissions in Henan Province from 2001 to 2020. The STIRPAT model was extended to qualitatively and quantitatively analyze the various factors influencing agricultural carbon emissions. Accounting for the defects of traditional prediction models, such as over-fitting, fuzzy nonlinear relationships, and insufficient generalization ability, an agricultural carbon emission prediction model based on the RBF (radial basis function) kernel ε-SVR (support vector regression) was established to predict agricultural carbon emissions and trends in Henan Province from 2021 to 2025 under different scenarios. Agricultural CO2 emissions in Henan Province showed an overall “increasing-decreasing” trend from 2001 to 2020, with an annual growth rate of −1.18%, and reached peaks of 1.0257×108 t in 2005. The main emission sources of agricultural CO2 in Henan Province had changed from enteric fermentation and manure management in animal husbandry to land utilization and rice cultivation in planting industry. Every 1% increase in rural population, crop sown area, number of large livestock, agricultural GDP per capita, per capita rural disposable income, agricultural mechanization level, and urbanization rate caused changes in agricultural CO2 emissions of 0.162%, 0.175%, 0.130%, −0.018%, −0.029%, 0.120%, and −0.071% in Henan Province, respectively. Among the seven factors affecting agricultural carbon emissions in Henan Province, the sown area of crops had the largest promoting effect, followed by the rural population and the number of large livestock, and the agricultural mechanization level had the smallest promoting effect. The urbanization rate had the strongest inhibitory effect, followed by the rural per capita disposable income, and per capita agricultural GDP had the least inhibitory effect. Under the baseline scenario, agricultural CO2 emissions in Henan Province will continue to decline from 2021 to 2025, and the predicted value in 2025 will be 6.4838×107 t, a decrease of 10.89% compared with 7.276×107 t in 2020. The low carbon scenario I presents a faster decline rate than the baseline scenario, with a predicted value of 6.3692 ×107 t in 2025, a decrease of 12.47% compared with 2020. Under low carbon scenario Ⅱ, the decrease rate of agricultural CO2 emissions in Henan Province is the highest, and the predicted value in 2025 is 6.3383×107 t, which is 12.89% less than that in 2020. This study showed that agricultural carbon peaking had been achieved in Henan Province. The further governance of agricultural carbon emissions should focuse on the land utilization of crops and manure management of large livestock, and the focus of promoting agricultural carbon emission reduction should be to steadily promote urbanization and rural economic development. Compared with the baseline scenario, the low-carbon scenario has greater carbon emission reduction potential and can realize the efficient development of the rural economy, urbanization process, and low-carbon agriculture, which will help accelerate the realization of the province’s Carbon Peaking and Carbon Neutrality goal.
Agricultural input-output efficiency and the potential reduction of emissions in Henan Province at the county scale
ZHU Yongbin, MA Xiaozhe, SHI Yajuan
2022, 30(11): 1852-1861.   doi: 10.12357/cjea.20220219
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Agricultural modernization and technological progress have substantially improved the efficiency of production. However, the growing dependence on the inputs of agricultural materials has resulted in a series of deleterious issues, such as soil and water pollution, carbon emissions. Previous studies have always considered carbon emissions as an unexpected output when evaluating agricultural green total factor productivity. These studies failed to estimate the potential reduction in carbon emission, as well as the contribution of all sources. This study sought to improve commonly used approaches and enable them to calculate the potential reduction of carbon emissions. To do so, it utilized the variable returns to scale data envelopment analysis (VRS-DEA) two-stage model and the DEA-Malmquist method to evaluate the agricultural input-output efficiency and obtain the abundant input of each material. In this study, six agricultural materials were selected as inputs and five major crop products as outputs with 105 counties/cities in Henan Province, China, as decision-making units from 2000–2020. The results showed the following: 1) carbon emissions induced by agricultural inputs began to decline after reaching their peak in 2016. The counties/cities with higher emissions were primarily distributed in the eastern and southern plains. Those with higher intensities of emissions per unit of sown area were primarily concentrated in the northern plains, where have better terrain conditions. 2) High-agricultural-efficiency areas were primarily concentrated in southern and northern Henan. In contrast, low-agricultural-efficiency counties/cities were primarily concentrated near urbanized areas, indicating that urbanization has a negative effect on agricultural efficiency. Approximately 60% of the counties/cities improved their agricultural efficiency between 2000 and 2020. Those with decreased agricultural efficiency were primarily located in the central and western regions. They were adjacent to areas with a high urbanization rate and primarily included mountainous and hilly areas. 3) The comprehensive potential reduction of carbon emission was approximately 11% of gross agricultural emissions. Counties/cities with the highest potential rate of reduction were primarily distributed in the areas surrounding the developed urban agglomerations. The key areas of agricultural reduction were the three counties/cities of Ruzhou, Xinye, and Huixian, with an accumulated potential reduction of more than one million tons. Ten counties/cities, such as Huaibin and Weihui, had more than half a million tons of accumulated potential reductions. 4) Agricultural inputs with a high redundancy ratio were agriculture plastic films, pesticides, chemical fertilizers, agricultural machinery, and agricultural labor. Chemical fertilizers with immense usage was a major concern; its input had the potential reduction of carbon emission as much as 83.5%. In summary, it is the basic solution for reduction of agricultural carbon emission to increase agricultural input-output efficiency and reduce redundant agricultural inputs. uts.
Impacts of agricultural infrastructure on ecology total factor productivity of grain from the perspective of environmental regulation
LI Ziqiang, YE Weijiao, MEI Dong, ZHENG Ciwen
2022, 30(11): 1862-1876.   doi: 10.12357/cjea.20220214
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Increasing grain production while protecting the environment is an important prerequisite for ensuring sustainable development and food security of China. To explore effective strategies to improve the ecology total factor productivity of grain (ETFP) in China, this study used the Global-Malmquist-Luenberger (GML) index to measure the ETFP based on the ecological value of grain production. Based on the theory of public goods, we empirically explored the path to improve ETFP with agricultural infrastructure as the point of penetration. We found: (1) The ecological value of grain production per hectare in 30 provinces (cities, autonomous regions) of China increased from 1993 to 2019. The average ETFP during 1993–2019 generally showed a fluctuating upward trend. Among them, the ETFP of the Middle and Lower Reaches of the Yangtze River and the Northeast China were higher than the national average in most years. (2) Agricultural water conservancy facilities, agricultural electric power facilities, and agricultural transportation facilities can effectively improve ETFP, but there was a lag in time. Among these factors, the impact of agricultural water conservancy facilities on ETFP showed an “inverted U” shape. This finding suggests that there is an optimum value for the provision of agricultural field water conservancy facilities in the process of ecological food production. (3) In contrast to the full-sample regression results, the regression results of samples of northern and southern regions showed that the agricultural water conservancy facilities and their lag terms had no significant impact on ETFP, and the agricultural electric power facilities and their lag terms had a reducing effect on ETFP in southern region. The results of the sample regression showed that agricultural electric facilities and their lag items in main grain-producing areas had no significant impact on ETFP, while agricultural electric power facilities and their lag items in non-main grain-producing areas had no significant impact on ETFP. (4) The results of the moderating effect test indicated that environmental regulation had a positive moderating effect on ETFP. Further study found that, in the grouping regulation regression results, environmental regulation could play a stronger positive regulatory role in the region with a lower ETFP than in the region with a higher ETFP. Therefore, on the basis of this research, we recommend that the government should plan and invest in agricultural infrastructure construction in advance and formulate and publicize scientific, reasonable, and flexible environmental laws and regulations. This study innovatively incorporates the ecological value of grain production into the measurement of ETFP. While broadening the research boundary of agricultural infrastructure construction planning, it provides a basis for improving the ETFP in China.
Influence of consumption motivation and consumption habit on premium payment intention of ecological agricultural products using green manure-rice as an example
LI Fuduo, YIN Changbin
2022, 30(11): 1877-1890.   doi: 10.12357/cjea.20220337
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Over the past few decades, the intensive use of chemicals in agricultural production in China has led to serious environmental and food safety problems, triggering a series of public health incidents and greatly undermining consumer confidence in traditional food. Due to food safety concerns, consumers in developed as well as developing countries such as China have been paying increasing attention to emerging ecological agricultural products (EEAPs) produced in environmentally conscious way. In the consumer market, guiding consumers to pay reasonable fees for EEAPs is not only conducive to promote the cultivation and development of the EEAPs market but also has important practical significance for improving the health of residents and ensuring environmental protection. Using green manure-rice (GMR) as an example, based on survey data from 974 consumers in Changsha, Wuhan, Nanchang, and Hefei in South China, this study first used the contingent valuation method (CVM) to evaluate consumers’ premium payment level for GMR. Then, the Heckman two-stage model was used to explore the mechanism of influence of consumer motivation and consumption habits on consumers’ willingness to pay (WTP) and to empirically test the moderating effect of external environmental cognition on the process by which consumer motivation affects WTP. The study showed that the average premium paid by consumers for GMR was 61.69%, the premium value calculated from premium ratio and conventional rice price was 3.27 ¥∙kg−1, and the actual price consumers willing to pay for GMR was 8.57 ¥∙kg−1. External environment cognition had the greatest influence on consumers’ WTP, and safety motivation and environmental motivation also had a significant positive influence on consumers’ WTP. Positive external environment cognition significantly improved consumers’ WTP by strengthening their safety and environmental motivation. In addition, young women with higher education level, children, and consumers with higher household income and pursuit of quality of life were more willing to pay a higher premium for GMR. Accordingly, this study had the following policy implications. First, a scientific pricing mechanism for green manure rice should be established as soon as possible to ensure improved returns for producers that are acceptable to consumers. Second, enhancing consumers’ cognition of the external environment is the key to encouraging them to pay a premium for GMR. The improvement of consumers’ comprehensive cognition of the external environment and the risks to the natural environment can enhance their perception of the value of GMR, thus increasing their WTP. Third, paying attention to consumers’ motivation contributes to a deeper understanding of the process and mechanism of premium payment behavior, which is conducive to shaping stable consumption preferences, thus improving the sustainability of consumers’ premium payments for GMR.

Editor-in-chief:LIU Changming

Competent Authorities:Chinese Academy of Sciences

Sponsored by:Institute of Genetics and Developmental Biology, Chinese Academy of Sciences; China Ecological Economics Society

Organizer:Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences

ISSN 2096-6237
CN 13-1432/S
  • Chinese core periodicals
  • Core Chinese Sci-Tech Periodicals
  • China's Top Science and Technology Periodicals
  • Covered by Chinese Science Citation Database (CSCD)
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