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Spatio-temporal variation in and the driving factors of desert vegetation in Xinjiang
CUI Can, GUO Ying, SHEN Yanjun
 doi: 10.13930/j.cnki.cjea.210121
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Desert vegetation is an important part of arid and semi-arid ecosystems in Xinjiang and plays a key role in the maintenance of ecosystem balance. Timely and accurate monitoring of the temporal and spatial distribution of desert vegetation is important for the sustainable utilization of the resources and ecological restoration. Based on remote sensing technology combined with two Normalized Difference Vegetation Index (NDVI) products (AVHRR-NDVI and MOD13A2-NDVI), the area of desert vegetation in Xinjiang from 1989 to 2017 was estimated. The temporal and spatial characteristics of desert vegetation in three typical river basins (Ulungur River Basin, Aksu River Basin, and Yarkand River Basin) were analyzed, and the relationships between desert vegetation and the climate factors, runoff changes, and policy factors were discussed. The NDVI products were used to calculate the vegetation coverage ( fc), and the distribution and area of desert vegetation were determined according to the threshold of vegetation coverage. Desert vegetation was determined within the fc threshold range of 0.1–0.35, where 0.1–0.25 indicates low-coverage desert vegetation and 0.25–0.35 indicates high-coverage desert vegetation. The transformation between desert vegetation and other vegetation types was calculated using the land use transfer matrix to explore the evolution and transformation of desert vegetation in Xinjiang from 1989 to 2017. The driving factors of desert vegetation evolution in the three typical river basins were analyzed using correlation analysis. The results showed that the total area of desert vegetation in Xinjiang significantly increased from 1989 to 2017 at a rate of 30 900 hm2∙a−1. The area of low-coverage desert vegetation significantly increased at a rate of 32 200 hm2∙a−1; whereas the area of high-coverage desert vegetation did not vary, with a multi-year average value of 2 087 100 hm2. The area of desert vegetation in northern Xinjiang increased slightly, accounting for 67% of the total area of desert vegetation. This was mainly due to an increase in low-coverage desert vegetation. The area of high-coverage desert vegetation in northern Xinjiang slighly decreased. The desert vegetation area in southern Xinjiang significantly increased. During vegetation transformation, 508 500 hm2 of desert vegetation transformed from high to low desert vegetation, 3.4124 million hm2 of non-desert vegetation types transformed into desert vegetation, and 1.9125 million hm2 of desert vegetation transformed into non-desert vegetation types. This study of typical river basins showed that the area of desert vegetation increased with increasing precipitation. Precipitation was the most important factor affecting the evolution of desert vegetation, followed by runoff and policy factors. The influence of air temperature on desert vegetation varied across regions, and the area of desert vegetation near water increased with increasing temperature.
Realization path of moderate expansion of management scale of urban leisure agriculture
LI Yufeng, LI Shanwei, XU Pu
 doi: 10.13930/j.cnki.cjea.210339
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It is necessary to determine how to appropriately expand the scale of leisure agriculture entities under constraints of existing resources and effectively promote sustainable development of urban leisure agriculture for realization of large-scale operational willingness of urban leisure agriculture entities limited to resources and policy restrictions of metropolises. Based on questionnaire data of 87 leisure agriculture entities in Shanghai, this study constructed a Logistic-ISM (interpretation structure model) model and took the willingness of leisure agriculture entities as measurement targets to study significant factors that affected the willingness, and logical hierarchical relationships between factors. Results showed that moderate expansion depended on the influence of the three levels of factors: 1) Among deep-seated factors, the leisure agriculture entities supported by government construction land were more willing to expand the scale of farmland. 2) Among middle-level indirect factors, the characteristics of agricultural resources, scientific park planning, innovative management capabilities, and business industrial structure positively affected the willingness of leisure agriculture entities to expand the scale of farmland, while the ecological nature of agricultural production was strong, the expansion of operators’ willingness to farmland size was weak. 3) Among the direct factors at the surface level, culturally functional leisure agriculture entities were willing to expand the scale of farmland, while leisure functional management entities tended to reduce the scale of farmland. To promote moderate scale operation of urban leisure agriculture, the government should introduce state-owned enterprises to play a demonstration effect to revitalize stock of rural land resources, and release value of resources. At the same time, leisure agriculture should provide strategic space for urban core functions, fully consider the heterogeneity of leisure agriculture entities, dig deep into rural cultural heritage, and promote transformation from undertaking the function of guaranteeing the supply of agricultural products for multiple functions to highlighting the economic, ecological, and esthetic values of agriculture and rural areas.
Impacte of saline irrigation and application of N and P on growth and nutrient distribution of Tamarix chinensis planted in coastal saline-alkali soil
QIU Fagen, YANG Lilin, LIU Min, ZHU Xiangmei, CHEN Shuling
 doi: 10.13930/j.cnki.cjea.210209
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Saline irrigation is a highly effective method of elimination of salt and drought stress in spring in the coastal severe saline-alkali soils. Tamarix chinensis, a salt-tolerant plant, plays an important role in reforming the ecological landscape of the coastal wetlands in northern China. However, the responses of plant growing rhythm of T. chinensis to long-term saline irrigation-associated fertilization remain unclear. To promote the rapid growth of T. chinensis for carbon (C) fixation, landscape construction, and saline-alkali soils reclamation, an experiment involving irrigation with local phreatic saline resources and application of nitrogen (N) and phosphorus (P) was conducted to alleviate spring drought and salt stresses, and solve the prominent problems of soil N and P deficiencies in the coastal severe saline-alkali soil. The experiment was consisted of two factors of saline irrigation and N and P fertilization over a four-year period in the coastal saline-alkali soil in the low plain of North China. Six treatments included no fertilizer as control (CK, WCK), only applying N (N, WN), applying both N and P (NP, WNP), each corresponding to no irrigation (the first) and irrigation with local phreatic saline water containing 8.02−9.34 g·L−1 salt (the second), respectively. The results showed that the growth and resprouting of T. chinensis occurred mainly in spring till to summer, but plant height and diameter increase and resprouting did not synchronized simultaneously. The trends of rates of plant height growing, resporuting and stem diameter thickening of T. chinensis during the growth season were as sloping shapes, triangle, and up fast following down slowly, respectively. In the first year of saline irrigation, soil water content, fresh weight of plant and leaf dry weight of T. chinensis was reduced significantly (P<0.01); but the stem dry weight was not impacted. However, after three-year saline water irrigation, the plant height and diameter growth was inhibited, the N content of stem and leaf were decreased significantly (P<0.05), but the P content of leaf increased by 11.8% on average, and branch numbers of T. chinensis increased significantly (P<0.05). The WNP treatment, i.e. saline irrigation and applying NP, retarded the decline of growth rate of plant height and stem diamter during spring to summer (May−June), not only accelerated the resprouting rate, but also increased the N content of stems and leaves, and promoted the transfer of Ca2+ and Mg2+ from stem to leaves, which resulted in a distribution change of ion in stem and leaf. WNP can alleviated the negative effect of continuous saline irrigation on the growth of T. chinensis by accelerating resprouting, promoting nutrient absorption and ion transport. The results provides a support for rational saline water irrigation and fertilization for T. chinensis in the costal serious saline alkali soil.
Different impacts of Micro-Nano bubbles on the yield formation of the different rice type
QIAN Yinfei, CHEN Jin, SHAO Caihong, GUAN Xianjiao, QIU Caifei, CHEN Xianmao, LIANG Xihuan, XIE Jiang, DENG Guoqiang, PENG Chunrui
 doi: 10.13930/j.cnki.cjea.210194
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Increasing the rhizosphere oxygen of the rice paddy can influence the paddy field environment and improve the physiological and metabolism of the rice and improve the grain yield. Traditional mechanically aerated subsurface irrigation and chemically aerated subsurface irrigation could produce large air bubbles in soils, which can escape the soil along pores adjacent to the roots, Improving aerating irrigation efficiency is an issue remaining to be resolved. One way in which is to use water rich in micro-nano bubbles (MNB), MNB can produce small air bubbles in soils and not easy to escape from the soil and thus supply more oxygen. Different rice type may have different ability to absorb and use the oxygen. In order to find the difference of the effect on the different rice types under the MNB, A potted experiment with the treatments of MNB and the running water as check (CK) was tested during the year 2019−2020 in order to know the different impacts of the MNB and CK on the growth and yield formation of two kind of paddy rice variety (inbred rice ‘Ganwanxian37’ and super rice ‘WufengyouT025’). The result showed that, 1) MNB obviously increased the dissolved oxygen concentration of the paddy rice soil, increased the number and volume of the roots of the paddy rice, enhanced α-NA oxidation and improved the total and the active absorption area of the rice root, promoted the leaves 's SPAD and Pn value, increased the biomass accumulation, raised the harvest index, improved the paddy rice's panicle characteristics, increased the panicle length, improved the number of grains per panicle length, enhanced the number of the primary & secondary branches and the cob, as well as the grains and seed-setting rate on the primary & secondary branches and the cob, and finally enhanced the grain yield. 2) MNB obviously enhanced the yield of the two kind of type of paddy rice, in which the inbred rice enhanced 8.46%−17.9%, while the super rice enhanced 11.32%−22.09%. the super rice enhanced more grain yield than the inbred rice. 3) MNB mainly increased the panicles (6.67%−16.67%)of the inbred rice and the spikelets per panicle (3.23%−7.2%)and the seed-setting rate (1.14%−6.57%) of the super rice. 4) the main reason that MNB enhanced the panicles of the inbred rice is that the NMB promoted the tiller occurrence in the earlier growing period and enabled the inbred rice to get more tillers and got the max tillers. While the main reason that MNB enhanced the number of the spikelets per panicle and the seed-setting rate of the super rice is that MNB enhanced the photosynthesis of the leaves (improved the leaves’s SPAD and Pn value) and slowed down the senescence of the leaves, improved the bearing rate of the tillers and biomass accumulation, increased the number and the seed-setting rate of the grain of the secondary branches and the main cobs, and finally improved the harvest index. It is thus clear that, the MNB can improve the yield of the two kind of type paddy rice. The inbred rice may increase the MNB supplies before the tillering stage to increase the panicles to increase the yield, while the super rice may increase the MNB supplies after the earing stage to enhance the spikelets per panicle and the seed-setting rate to increase the yield.
Effects of phosphorus fertilizer application rate on the content of Hedley’s phosphorus fractions in calcareous soil and phosphorus accumulation amount in crop
XU Xiaofeng, MI Qian, LIU Di, FU Senlin, WANG Xugang, GUO Dayong, ZHOU Wenli
 doi: 10.13930/j.cnki.cjea.210186
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Excessive application of phosphate fertilizer not only wastes phosphorus resources, but also brings eutrophication problems in lakes and rivers. In order to clarify the effect of reduction of phosphorus fertilizer applying rate on phosphorus fractions in calcareous soil and its relationship with crop phosphorus accumulation, three treatments were set up, i.e. phosphorus applying rate 150 kg·hm−2 (P150), 37.5 kg·hm−2 (P37) and 0 kg·hm−2 (P0). After two consecutive years of "wheat-corn" crop rotation, the content changes of soil phosphorus fractions were studied with Hedley soil phosphorus grouping method, and its storage contribution rate and output contribution rate were estimated. The relationship between soil key phosphorus fractions, phosphorus fertilizer application rate and crop phosphorus accumulation were explored with regression analysis, path analysis and structural equation model. The results showed that compared with P37, P150 led to a significant increase in soil total phosphorus. And the phosphorus content of resin_Pi、NaHCO3_Pi、NH4OAc_Pi、Fe_Pi、NaHCO3_Po in P150 were significantly higher than that of P37. While the other fractions had no significant change. P0 did not cause a significant decrease in the content of soil phosphorus fractions. The storage contribution rates of soil inorganic phosphorus fractions and organic phosphorus fractions were 72.6% and 23.8%, respectively. Among them, the storage contribution rates of HCl_Pi, Fe_Pi, NH4OAc_Pi, resin_Pi, and HCl_Po were 24.45%, 18.1%, 13.62%, 11.15%, and 9.30%, respectively. The output contribution rate of soil inorganic phosphorus fractions was 41.0%, and that of organic phosphorus fractions was 56.4%. Among them, the output contribution rates of HCl_Po, Fe_Pi, and NH4OAc_Pi were 39.44%, 17.36%, and 13.06%, respectively. The output contribution rates of HCl_Pi and resin_Pi were only 1.91% and 0.40%. In the structural equation model, the load factors of phosphorus fertilizer applying rate on Fe_Pi, HCl_Pi, NH4OAc_Pi, resin_Pi, NH4F_Po, NaHCO3_Pi, NaHCO3_Po were 0.078, 0.077, 0.061, 0.036, 0.018, 0.015, 0.012, respectively. The load factors of Fe_Pi, NH4OAc_Pi, HCl_Po on crop phosphorus accumulation amount were 0.355, 0.334, −0.039, respectively. The above results show that in calcareous soil, Fe_Pi, NH4OAc_Pi, HCl_Po were the key phosphorus fractions. Among them, Fe_Pi and NH4OAc_Pi were easily consumed when no phosphorus fertilizer was applied, but they can also be easily supplemented by phosphorus fertilizer application. HCl_Po was available for crop but was not easy to be replenished by phosphorus fertilizer application. The high storage contribution rate and low output contribution rate of HCl_Pi fraction was the important reasons for the low efficiency of phosphate fertilizer in the current season. It is suggested that the decision of phosphorus application rate should be based on the storage contribution rate of key phosphorus components.
Effects of nano-zero-valent iron (nZVI) on earthworm-bacteria-soil systems
LIU Chang’e, YUE Minhui, TAN Huilin, ZHANG Yue, ZHANG Weilan, XIAO Yanlan, PAN Ying, DUAN Changqun
 doi: 10.13930/j.cnki.cjea.210156
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Nano-zero-valent iron (nZVI) is widely used to remedy soil heavy metal pollution. However, the potential effects of nZVI on soil invertebrates, soil quality and microbial communities have not been well studied. In this study, we used Eisenia foetida (0, 10 pieces per kilogram soil) as the test species and examined the potential effects of nZVI (mass ratios of 0, 0.05%, 0.25%, and 0.50%) on the earthworm-bacteria-soil ecosystems after 15, 30, and 45 days of exposure. The results showed that after 45 days of exposure, there was no significant difference in survival rate and biomass of earthworms. The earthworm survival rate and content of malondialdehyde in the 0.50% nZVI system decreased by 27.66% and 0.86 nmol∙g−1, respectively, compared with those on day 15. However, the earthworm biomass increased by 1.20 times, and the catalase activity increased by 2.62 times. At the phylum or genus level, nZVI had no significant effects on the relative abundance, diversity index, and abundance index of soil microorganisms. Compared with the 0 nZVI system, the proportion of soil large aggregates (>250 μm), the average weight diameter of soil aggregates, and the content of available phosphorus (P) in the 0.50% nZVI system increased by 15.69%, 12.59%, and 21.20% under earthworm-mediated conditions, respectively. The proportion of soil macroaggregates and the average weight diameter of soil aggregates in the earthworm and nZVI composite systems were significantly higher than those in the corresponding single nZVI system, and earthworm activity significantly improved the stability of soil aggregates under nZVI stress (P<0.01). In this study, we found that long-term exposure to nZVI had no significant toxic effects on the community characteristics of soil microorganisms but promoted the growth of earthworms, which further improved the bioavailability of soil nutrients. This study provides a scientific basis for environmental safety assessments of nZVI in soil restoration applications.
Characteristics and environmental effects of nitrogen flows in the crop-livestock system of Jiangsu Province
YU Le, JIAO Yangmei, DING Shang, ZHU Zhiqiang, ZHAO Hongwei
 doi: 10.13930/j.cnki.cjea.210172
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With the rapid development of agriculture and animal husbandry, large nitrogen inputs have caused a series of environmental problems. To provide a scientific reference for regional nutrient management, Jiangsu Province, an economically developed region in the Yangtze River Delta, was selected to study the nitrogen flow characteristics in crop-livestock systems from 1998 to 2018 and their environmental effects. The research was based on the NUFER model (NUtrient flows in Food chains, Environment and Resources use, NUFER) and incorporated statistical yearbook data, survey data, and literature data. The nitrogen account balance, nitrogen use efficiency, nitrogen recycling, and loss of the crop-livestock systems in Jiangsu Province were quantitatively analyzed, and the relationships between the economy, resources, and environment of the crop-livestock systems were explored based on a structural equation model. The results showed that from 1998 to 2018, the crop subsystem increased the amount of nitrogen carried by the crop products under the gradual decrease of the total nitrogen imports of the subsystem. Nitrogen carried by the main crops and crop by-products increased from 8.31×105 t to 1.20×106 t. Total nutrient loss also declined. For the livestock-poultry subsystem, nitrogen was mainly introduced via exogenous and local feed; exogenous feed was the main source of nitrogen in the subsystem. The proportion of local feed nitrogen supply increased annually, from 29.32% in 1998 to 44.77% in 2018. From 1998 to 2018, the nitrogen use efficiency of the crop-livestock system increased from 21.39% to 35.00%. The amount of straw to field, local feed, and manure to field increased annually, and the total amount of recycled nitrogen increased from 2.54×105 t to 3.00×105 t. Nitrogen environmental emissions decreased in the past 20 years, and the main sources of loss included soil nitrogen surplus, gas emission loss, water discharge loss, and manure residue. The structural equation model results showed that in the developmental process of the agricultural and animal husbandry systems in Jiangsu Province, economic development and resource reduction promoted improvements in product output and system efficiency. Under the guidance of regional development and policies, crop-livestock systems in Jiangsu Province developed rapidly from 1998 to 2018. The scale of the agricultural and animal husbandry systems had continuously expanded, resource utilization had been relatively efficient, and environmental emissions had gradually decreased. However, there was also a slight imbalance in the development of crop-livestock systems, and there were relatively few combinations of crop-livestock. Future development of the agriculture and animal husbandry systems in Jiangsu Province should focus on coupling the crop and animal husbandry subsystems, moderately expanding the production scale, and balancing the development of agriculture and animal husbandry subsystems to promote local agriculture and animal husbandry.
Influencing factors of farmers’ willingness to adopt rice-crayfish co-culture and their heterogeneity
HU Naijuan, WANG Yutao, CHEN Qian, ZHU Liqun
 doi: 10.13930/j.cnki.cjea.210281
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In recent years, rice-crayfish co-culture has been vigorously promoted as an ecological agricultural mode. As a direct production decision-maker, farmers’ adoption intention and its influence mechanism should be clarified for the scientific promotion and sustainable development of rice-crayfish co-culture. Based on the questionnaire survey and on-the-spot interviews data of 603 farmers in five cities of Jiangsu Province, this study explored the influencing factors and their heterogeneity of farmers’ willingness to adopt the rice-crayfish co-culture mode using the theory of planned behavior and ordered logistic model. Results show that: 1) 56.88% of the farmers in the sample were willing to adopt the rice-crayfish co-culture mode, with income expectation as the key influencing factor. 2) Behavioral attitude, subjective norm, and perceived behavioral control had significant effects on farmers’ willingness to adopt the rice-crayfish co-culture mode. The order of influence was as follows: perceptual behavior control > behavior attitude > subjective norm. 3) Under different qualifications, the factors influencing farmers’ willingness to adopt the rice-crayfish co-culture mode were heterogeneous. Specifically, complete infrastructure and part-time industrialization had a stronger influence on the willingness to adopt this mode of farmers with a high expected income. The farmers who were given subsidies and less affedcted by neighborhood had a stronger willingness to adopt the rice-crayfish co-culture mode. Farmers who were less influenced by the neighborhood had higher requirements for technical training and easeness of learning. The neighborhood effect, guidance of the agricultural technology department, difficulty of technical learning, and level of education had a significant positive effect on the willingness of farmers who participated in the technical training. Distributing subsidies and improving the guidance effect from agricultural technology departments could increase farmers’ willingness to adopt this mode in areas with incomplete infrastructure. Neighborhood effect and part-time employment had a negative impact on the difficulty of technology training, while the income expectation and environmental expectation stimulated farmers to adopt the rice-crayfish co-culture mode. Based on these results, the following policy recommendations were put forward: firstly, the government should strengthen the technical training and guidance effect; second, farmland infrastructure should be improved; third, new agricultural management subjects should be fostered quickly; and finally, differentiated incentive and guidance policies should be formulated according to farmer types.
The development space of and recommendations for ecological farms in China
GAO Shangbin, SONG Chengjun, XU Zhiyu, SUN Renhua, XUE Yinghao, HU Xiaofang, QIAO Yuhui
 doi: 10.13930/j.cnki.cjea.210241
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Ecological farms are the main implementation objects for agricultural environmental policy in developed countries. Ecological farms represent the basic unit of promotion for ecological agriculture in China and have become an effective approach for agricultural green development. Based on a 7-year field investigation and 5 years of experience in the construction of eco-agriculture bases, the economic parameters of four regions of China (Northeast China, North China, the Middle and Lower Reaches of the Yangtze River, and South China) and three types of ecological farms (planting farm, breeding farm, plant-breeding combined farm) were obtained. According to the development plan of China’s new type of agricultural business and the proportion of 3%−5% ecological transformation, the development space of ecological farms at the regional and national scales was evaluated, and the industrial value of the ecological farms in promoting agricultural green development was analyzed. The latest requirements and policy recommendations for China’s recent ecological farm construction were put forward at the strategic level. The results show that: 1) the input-output efficiency of ecological farms in South China is the greatest and that in Northeast China is the lowest. With respect to ecological farm type, ecological farms carrying out planting-breeding have the greatest input-output ratio and average profit margin, but breeding-based ecological farms and planting-based ecological farms have lower input-output ratios and average profit margins. 2) There will be 30 000−50 000 ecological farms in China by 2022, and the scale of industrial value for the ecological farms ranks as North China > the Middle and Lower Reaches of the Yangtze River > Northeast China > South China, which will effectively drive market investment and provide employment opportunities. 3) Recently, it is necessary to build several ecological farms as the national demonstrations in the Yangtze River Delta region and other key areas, gradually promote the evaluation of ecological farms throughout the country. Meantime, optimizing the compensation policies, building a big data system, cultivating an industrialization platform, creating the investment and financing mechanism, and cultivating talented workforce and market subjects who would be engaged in the operation and management of ecological farms should be conducted.
Effects of fertilizer patterns on the potential nitrogen fixation rate and community structure of asymbiotic diazotroph in highland barley fields on the Tibetan Plateau
MA Ruiping, DAI Xianglin, LIU Guoyi, XIE Yongchun, GAO Xiaoli, GAO Xue
 doi: 10.13930/j.cnki.cjea.210148
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Free-living nitrogen fixation (FLNF) by diazotrophs is an important nitrogen (N) source in terrestrial ecosystems and may reprensent a viable solution to environmental pollution caused by N over-fertilization. Studying the impact of different fertilizer regimes in highland barley fields on the diazotrophic community profiles and potential N fixation rates (PNFR) may provide scientific fertilization strategies and a theoretical basis for agricultural green development in the Tibetan Plateau. Here, quantitative PCR, high-throughput sequencing and 15N labeling methods were used to better understand the impact of different fertilizer regimes on the abundance and composition of diazotrophs as well as the potential N fixation rates in highland barley fields on the Tibetan Plateau. The experiment included five treatments: a control without fertilizer (CK); N, phosphorus (P) and potassium (K) mineral fertilzers (F); manure fertilizer (M); mineral NPK fertilizers plus manure (FM); and mineral NPK fertilizer plus straw (FS). The results showed that: 1) compared with the CK and F treatments, the M, FM and FS treatments significantly (P<0.05) increased the contents of soil organic carbon (C) and total N. Moreover, the ammonium nitrogen (NH4+-N) content was significantly (P<0.05) higher in the FM treatment than in the other treatments. The highest contents of organic C, total N, nitrate N (NO3-N), available P and available K were observed in the M treatment, and their contents were significantly (P<0.05) higher than those in the other treatments. 2) The PNFR ranged from 2.63 to 4.07 μg∙kg−1∙d−1 under different fertilizer treatments. Fertilization, especially the application of organic fertilizers (sheep manure or straw), reduced the PNFR, and the inhibitory effect of straw on PNFR was higher than that of sheep manure. The soil NH4+-N content was the main factor affecting PNFR. 3) The M and FM treatments significantly (P<0.05) increased diazotrophic abundance, while the opposite was observed for the F and FS treatments. The total N content was the key factor affecting diazotrophic abundance. 4) Different fertilizer patterns significantly changed the diazotrophic composition, and the similarities in the diazotrophic compositions among different fertilizer regimes fell into three major categories: no fertilization (CK), organic fertilization (M), and chemical fertilization (F, FM, FS). Available P was the key factor regulating diazotrophic composition, followed by pH and C/N. In conclusion, the M treatment was the optimal fertilizer practice to improve soil fertility, increase diazotrophic abundance and reduce PNFR decline in highland barley fields on the Tibetan Plateau.
Progress and perspective in research on plant resistance mediated by root exudates
MAO Mengxue, ZHU Feng
 doi: 10.13930/j.cnki.cjea.210328
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Root exudates are a variety of biochemical substances actively or passively secreted by plant roots that play an important role in mediating material exchange, energy transfer and information exchange in plant rhizosphere microenvironments, as well as in plant responses to environmental stresses. Biotic and abiotic stresses can change the composition and quantity of root exudates and increase the content of defensive compounds in plant root exudates. Plants use different root exudates to resist biotic and abiotic stresses, including releasing toxic substances for direct defense, releasing volatile substances to attract natural enemies, interacting with microorganisms to resist biotic stresses, releasing root exudates with osmotic regulation and antioxidant capacity and coordinating hormone signals to resist abiotic stress. Additionally, root exudate flow increases the concentration of many common metabolites, changing the soil physical and chemical properties and microbial activities, and affecting the physiological and biochemical processes at the soil-plant interface, thereby, directly or indirectly improving plant stress resistance. In this paper, the effects of biotic and abiotic stresses on the composition and quantity of plant root exudates were reviewed, the mechanisms of plant defense against biotic and abiotic stresses mediated by root exudates were summarized, and the aspects needed to be further studied were also suggested, to provide a reference for further research on the adaptive mechanism of plants under stress.
Spatio-temporal changes of water resources ecosystem services in the Hanjiang River Basin based on the shared socioeconomic pathway
CHEN Zeyi, YU Peiheng, CHEN Yiyun, JIANG Song, BAI Shaoyun, GU Shixiang
 doi: 10.13930/j.cnki.cjea.210160
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A comprehensive assessment framework for watershed ecosystem services and trade-offs was proposed for watershed governance and regional sustainable development in this paper. The framework integrated both shared socioeconomic pathways (SSPs) and future land use simulation (FLUS) models. The socioeconomic data of China’s provincial SSPs considering domestic development and regional differences were introduced to the FLUS model, meeting the needs of regional level land-use simulation scenarios and fully considering the interaction between human socio-economic activities and the natural environment. Taking the Hanjiang River Basin as an example, the FLUS models under different SSPs scenarios were built to evaluate the ecological and environmental effects on land-use change. We further investigated the response of water conservation and water quality purification services to social development decision-making and spatiotemporal evolution by using InVEST model. Results showed that: 1) the water production depth in 2035 under all the SSP scenarios was significantly higher than that in 2015. The increment under the SSP1 and SSP2 scenarios was relatively small, and the increment under the SSP3 scenario was relatively higher with the most intense change. The areas with increased water production depth were mainly concentrated in the southeast, central, and western regions of the Hanjiang River Basin. 2) From 2015 to 2035, due to frequent human activities and rapid urban expansion, in areas where the water production depth increased, urbanized land also increased significantly. According to the land-use simulation and water production depth change results, urbanized land had a strong water production capacity due to low vegetation coverage, weak evapotranspiration, and low permeability of hardened ground. 3) The nitrogen and phosphorus loads in the SSPs scenarios in 2035 were lower than those in 2015. The reduction under the SSP1 and SSP5 scenarios was relatively large, and the SSP3 scenario was the same as that in 2015, but the change was the most intense. The areas with increased nitrogen and phosphorus loads were mainly concentrated in the southeast and western regions. 4) According to the results of land-use simulation and nitrogen and phosphorus load change, the urbanized land had more pollutants due to the frequent human socio-economic activities, while the cropland was due to the use of chemical fertilizers and pesticides in the process of agricultural production, making part of the nitrogen and phosphorus elements not absorbed by crops. The two types of land-use caused serious pollution in the water environment of the basin. 5) The future development planning of the Hanjiang River Basin can be based on the SSP1 scenario, referring to the economic and technological development model under the SSP5 scenario, combined with the basin functional district, optimizing the land-use structure, and ensuring the water ecological environment security of the basin while paying attention to economic development. The results of this study can be used to prepare territorial spatial planning and sustainable water resource asset management in the Hanjiang River Basin, support the construction of the Hanjiang River eco-economic belt, and promote the improvement of the water ecological environment in the Yangtze River Basin.
Effect of increased plant density with reduced nitrogen on yield formation and nitrogen use efficiency of hybrid rice under high temperature and high humidity conditions
JIANG Peng, XU Fuxian, ZHANG Lin, ZHOU Xingbing, ZHU Yongchuan, GUO Xiaoyi, LIU Mao, CHEN Lin, ZHANG Rong, XIONG Hong
 doi: 10.13930/j.cnki.cjea.210288
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The effects of increased plant density with reduced nitrogen (N) application rate on yield formation and nitrogen use efficiency (NUE) of hybrid rice were studied to provide a theoretical basis for optimum nitrogen fertilizer management and plant density under high temperature with high humidity conditions. Field experiments were conducted in Luzhou City from 2018 to 2019. The high yield and high quality hybrid rice variety ‘Nei6you107’ was grown under six combinations of plant density and N application rate: 1) locally recommended combination with a plant density of 16.5×104 hills∙hm−2 and a N rate of 180 kg∙hm−2 (LDNck); 2) combination of a plant density of 16.5×104 hills∙hm−2 and a reduced N rate by 15% (153 kg∙hm−2, LDN−15%); 3) combination of a plant density of 16.5×104 hills∙hm−2 and a reduced N rate by 30% (126 kg∙hm−2, LDN−30%); 4) combination of a increased plant density by about 27% (21.0×104 hills hm−2) and a reduced N rate by 15% (153 kg∙hm−2, HDN−15%); 5) combination of a increased plant density by about 27% (21.0×104 hills∙hm−2) and a reduced N rate by 30% (126 kg∙hm−2 HDN−30%); and 6) combination of a plant density of 16.5×104 hills∙hm−2 and zero N rate (LDN0). The grain yield, yield components, dry matter, N uptake and NUE were measured. The results showed that the grain yield of hybrid rice was significantly affected by different combinations of plant density and N rate (P<0.01). HDN−15% and HDN−30% produced higher grain yields than LDNck by 4.3%−4.9% and 2.3%−3.6%, respectively. The higher grain yields under HDN−15% and HDN−30% were attributed to improvement in spikelets per panicle, grain filling rate, translocation of dry matter accumulated at heading stage (TDMHD), translocation percentage of dry matter accumulated at heading stage (TPDMHD), contribution percentage of pre-anthesis dry matter translocation to grain yield (CPDMTGHD) and harvest index. The LDN−15% and LDN−30% had 2.3%−2.5% and 4.8%−5.0% lower grain yield than LDNck, respectively. The yield gap between LDN−15%, LDN−30% and LDNck was attributed to the difference in effective panicles, total dry matter, dry matter accumulation from heading to maturity, and contribution percentage of dry matter accumulation from heading to maturity stage to grain yield (CPDMGHD-MA). The HDN−15% and HDN−30% had lower nitrogen accumulation from heading to maturity and total N uptake than LDNck, whereas the translocation of N accumulated at heading stage (NTGNHD), translocation percentage of N accumulated at heading stage (TPNHD), contribution percentage of pre-anthesis N accumulation translocation to grain N accumulation (CPNTGNHD), N use efficiency for biomass production (NUEBP), N use efficiency for grain production (NUEGP) and N harvest index under HDN−15% and HDN−30% were higher than those under LDNck. Consequently, HDN−15% and HDN−30% had lower N requirements to produce 100 kg of grain (NRPG) than LDNck by 6.8%−8.4% and 9.0%−9.9%, respectively. HDN−15% enhanced the agronomic efficiency of applied N (AEN) by 36.7%−37.4%, partial factor productivity of applied N (PFPN) by 22.8%−23.5% and recovery efficiency of applied N (REN) by 5.6%−12.0% over LDNck. The HDN−30% produced higher AEN, PFPN and REN than LDNck by 55.5%−60.4%, 46.3%−48.2% and 17.0%−20.0%, respectively. The rational combination of plant density and N rate can improve panicle number per unit area, grain filling, TDMHD, TPDMHD, NTGNHD, TPNHD and harvest index, which further increasing the grain yield and NUE. The optimum combination is plant density of 21.0×104 hills∙hm−2 plus N rate of 126−153 kg∙hm−2 in high temperature with high humidity condition.
The effects of nitrogen fertilizer deep placement on the ammonia volatilization from paddy fields in the Taihu Lake region of China
WANG Shuwei, LIN Jinghui, WU Zhenggui, CHEN Ji, PAN Yunjun, SHENG Xuewen
 doi: 10.13930/j.cnki.cjea.210119
Abstract(68) HTML(12) PDF(28)
.Ammonia (NH3) volatilization is an important nitrogen (N) loss pathway in paddy fields. However, the effects of N fertilizer deep placement, slow-release N fertilizers, and urea inhibitors on NH3 volatilization reduction during the entire rice-growing season remain uncertain. To fill this knowledge gap, we conducted a field experiment with seven treatments: (1) no N application, (2) local broadcasting application of urea at a rate of 300 kg(N)∙hm−2 (SN300), (3) 10% reduction of N from SN300 (SN270), (4) deep placement of basal urea together with the broadcasting of topdressing of urea at tiller and panicle stages of rice, at a total a rate of 270 kg(N)∙hm−2 (DN270), (5) application of urea inhibitor for DN270 (DN270+UI), (6) 10% nitrongen reduction deep application of basal urea together with the surface application of slow-release N fertilizer (DN270+SR), and (7) application of urease inhibitors for DN270+SR (DN270+SR+UI). Compared with the SN300 treatment, deep placement of basal N fertilizer reduced the cumulative NH3 emissions by 78.2%−85.2% in the basal fertilization period. The combined application of the urease inhibitors in the rice topdressing periods (DN270+UI treatment) reduced the NH3 emissions by 30.4% at the tillering stage and 25.3% at the panicle stage in comparison with the SN300 treatment. Replacing urea with a slow-release N fertilizer (DN270+SR treatment) in the rice topdressing peirods reduced NH3 volatilization by 36.4% at the tillering stage and 28.1% at the panicle stage. The cumulative NH3 volatilization changed in the following order: SN300 > SN270 > DN270 > DN270+UI > DN270+SR > DN270+SR+UI. Compared to the local treatment (SN300), DN270+SR+UI significantly reduced NH3 volatilization by 50.9%. There was no significant difference in rice yield among the N fertilizer treatments. NH3 emission intensity per unit rice yield was lowest for the DN270+SR+UI treatment, 52.5% lower than the SN300 treatment. Overall, simultaneous N fertilizer deep placement with slow-release N and urease inhibitors produced more grains with lower environmental costs associated with NH3 emissions. This represents a promising and sustainable management strategy for paddy fields in the Taihu Lake region of China.
Measurement, spatial spillover and influencing factors of agricultural carbon emissions efficiency in China
WU Haoyue, HUANG Hanjiao, HE Yu, CHEN Wenkuan
 doi: 10.13930/j.cnki.cjea.210204
Abstract(13) HTML(0) PDF(12)
The efficiency of agricultural carbon emissions is a bridge between crop production and emission reduction, acting as a critical indicator of the potential for emission mitigation in agricultural production. In previous estimations, the outcomes yield the input-output efficiency of agriculture under the carbon emission constraint, rather than the efficiency of agricultural carbon emission, due to failing to separate the contribution of carbon emissions from other factors. To optimize the existing idea and understand the efficiency more precisely, a theoretical framework and a corresponding equation were developed for analysis in this study. In agricultural production, given the input factors, the efficiency of agricultural carbon emissions under the prerequisite of no desirable output was defined as the ratio of the minimum possible emissions to the actual emissons. On this basis, the GB-US-SBM model was employed to calculate the slack of emissions in 30 Chinese provinces from 2000 to 2019, reflecting the distance between the actual emission and production frontier. Then, the efficiency was estimated based on the slacks and actual emissions. Finally, the influencing factors and spillover effects of agriculural carbon emissions efficiency were explored using the spatial Durbin model. Results showed that: (1) From 2000 to 2019, the average agricultural carbon emissions efficiency was 0.778 in China, indicating considerable potential for emission reduction. At the provincial level, only Inner Mongolia and Qinghai had an efficiency of 1.000, while the rest of the provinces had different spaces for emission mitigation. (2) According to the emissions quantity and efficiency, the 30 provinces were divided into four groups. The five provinces, Henan, Hebei, Shandong, Heilongjiang, and Guangxi, belonged to a group of high emissions with high efficiency. The group of low emissions with high efficiency accounted for the majority, including 12 provinces, such as Inner Mongolia and Gansu. The group with high emissions and low efficiency covered seven provinces, such as Hunan and Hubei. Six provinces, including Zhejiang and Fujian, were classified as low emissions with low efficiency. (3) The global Moran’s index was significantly greater than 0, with a P-value under 0.01, verifying that there was a positive spatial autocorrelation in the provinces. The spatial econometric regression showed that efficiency had a significant positive spatial spillover effect, suggesting that an interactive evolution existed among close provinces. Specifically, four factors—industry structure, investment intensity, financial support for agriculture, and the degree of disaster, harmed the agricultural carbon emissions efficiency directly. By contrast, the irrigation effectiveness and urbanization indicated significant positive effects. In terms of spillover effects, the intensity of a disaster in a province negatively affected the efficiency of agricultural carbon emissions in neighboring provinces, while the urbanization rate exhibited a positive effect. Hence, it was essential to pay attention to the key factors that influence efficiency. Making full use of spillover effects could also help in achieving regional agricultural low-carbon transition. Additionally, local solutions should be addressed, owing to the regional characteristics of efficiency. This study results could provide a theoretical basis for the development of low-carbon agriculture in China.
Analysis of mechanical grain harvesting quality and its influential factors of spring maize in Shanxi Province
YAN Xiaoguang, LI Hong, DONG Hongfen, LI Aijun, WANG Guoliang, ZHOU Nan, HU Ying, DU Yanwei
 doi: 10.13930/j.cnki.cjea.210151
Abstract(12) HTML(1) PDF(1)
The study of mechanical grain harvesting quality and its influential factors is significant for popularizing mechanical maize harvesting technology in Shanxi Province and enhancing the core competitiveness of the maize industry. To study the influence of harvest time on the quality and yield of maize mechanically grain harvested, five maize varieties suitable for mechanical harvest were harvested at six times (Septmber 24th, and October 1st, 8th, 15th, 22th and 29th) by the same harvester and driver. The grain moisture content, broken rate, impurity rate, as well as ear loss rate, grain loss rate, total loss rate and yield of maize were investigated. The results were as follows: first, the grain moisture content declined gradually with a delayed harvest time. With a delayed harvest time, the grain broken rate and loss rate decreased rapidly in the early period but was stable and slightly increased in the later period. Furthermore, with a delayed harvest time, the impurity rate declined gradually and tended to be stable at the end. Finally, with a delayed harvest time, the ear loss rate increased gradually. The average yield when the field was harvested on October 15th was 11.9% higher than that harvested on September 24th. The high grain broken is the main factor limiting the quality of mechanical grain harvesting of spring maize in Shanxi Province. The relationship between grain moisture content and broken rate could be fitted in the model y=0.03x2−1.224x+16.78 (R2=0.802**). The grain broken rate was the lowest when its moisture content was 20.4%. When the grain moisture content was between 15.6% and 25.2%, its broken rate was less than the national standard of 5%. Choosing the optimal variety for mechanical harvest in the spring maize area of Shanxi Province and harvesting on October 15th could guarantee harvesting quality and yield. ‘Changdan 511’ ‘Dika 159’ and ‘Changdan 716’, which have both perfect mechanical harvest quality and high yield, could be used as mechanical harvest varieties in the spring maize area of Shanxi Province.
Temporal and spatial characteristics of China’s provincial green total factor productivity of grains from the ecological value perspective
ZHOU Yingheng, YANG Zongzhi
 doi: 10.13930/j.cnki.cjea.210106
Abstract(10) HTML(0) PDF(3)
Green development is important for China’s future food safety, and measuring green productivity is an effective method to explore ways to increase green grains production. Based on the differences in the endowment of cultivated land resources in different regions, this study adopted the ecological services value evaluation method to measure the ecological value of cultivated land during the process of grain production. To incorporate the nutrient pollution and non-nutrient pollution generated in the process of grain production, the global Malmquise Luenberger index and the super efficiency model were used from the static and dynamic perspectives, to calculate China’s total factor productivity and input-output redundancy rate from 1997 to 2019. To better understand the temporal and spatial changes in China’s green total factor productivity, the spatial development characteristics of the agricultural production factors were investigated in the selected six years (1997, 2001, 2005, 2009, 2013 and 2019) using the equidistant distribution method, and Moran’s I index was used to study the spatial heterogeneity and agglomeration of green total factor productivity of grains in China. The results showed that: 1) During the study period, the ecological value of grain production reduced by 0.39%, from 647.157 billion Yuan in 1997 to 644.616 billion Yuan in 2019; a loss of 2.541 billion Yuan. The ecological value in the northeast, central, and southwest regions increased, whereas that in the east and northwest regions decreased. 2) Analysis of the environmental impact of grain production showed that the traditional total factor productivity, which does not consider environmental effects, tended to ignore the positive and negative aspects of grain production and cannot accurately assess the true efficiency of China’s grain production. After accounting for environmental factors, such as the ecological value of grain production and agricultural non-point source pollution, this study found that the green total factor productivity of grains increased by 0.60% annually, from 0.9754 in 1997 to 1.0990 in 2019, driven mainly by technological progress (1.0308). The driving effect of technical efficiency (0.9973) was weak. 3) The proportion of provinces (cities) that were relatively effective in the green total factor productivity of grains increased from 9.68% in 1997 to 67.74% in 2019. In terms of time and space, the relatively effective provinces (cities) was mainly in the eastern region and then gradually developed to the northeast, central, and northwest regions. 4) Due to high pollution emissions and resource consumption, the main reasons for the provinces (cities) that were relatively ineffective in green total factor productivity of grains were the redundancy of employees in the primary industry, the use of agricultural film, and carbon emissions. 5) The green total factor productivity of grains in China had a significant positive spatial correlation dominated by high-high agglomeration, and the green total factor productivity of grains showed spatial characteristics of agglomeration in the central and southwestern high-efficiency areas. The degree of agglomeration was increasing. Based on the above results, this study advocates for a better understanding of the positive and negative effects of grain production activities, strict control of the non-grain and non-agricultural phenomenon of agricultural land, and the promotion of advanced agricultural technologies to promote the green total factor productivity of grains.
Regional differences, dynamic evolution, and convergence of the carbon compensation rate of planting industry in China
WU Guoyong, CHEN Ying, SUN Xiaojun
 doi: 10.13930/j.cnki.cjea.210225
Abstract(66) HTML(8) PDF(25)
Global warming is an increasingly serious problem. Carbon emissions from agriculture had hindered its transition to green agriculture, and carbon emissions from the planting industry cannot be ignored. Reducing the regional differences and clarifying dynamic evolution and convergence of the carbon compensation rates in the planting industry are conducive to the benign development of low-carbon agriculture. At present, few studies consider both agricultural carbon sources and carbon sinks, and an in-depth analysis of the carbon compensation rate of the planting industry is lacking. Existing studies on the agricultural carbon compensation rate focus only on the spatial effect of agricultural carbon but do not effectively analyze the sources and convergence of regional differences in the carbon compensation rate of the planting industry. Therefore, this study considered both the carbon sources and the carbon sinks and estimated the carbon compensation rate of the planting industry in 31 Chinese provinces (municipalities and autonomous districts) from 2002 to 2018. The Dagum Gini coefficient decomposition method was used to measure and decompose the regional differences, the dynamic evolution process of kernel density with non-parametric estimation was investigated, and the σ-convergence, absolute β-convergence, and conditional β-convergence models were used to test the convergence characteristics of the carbon compensation rate. The results were as follows: (1) The overall relative difference in the carbon compensation rate of the planting industry tended to expand. The relative differences in the eastern region expanded, while the relative differences in the central and western regions showed only little change. The relative differences between the eastern and western regions and the eastern and central regions increased, whereas that between the central and western regions decreased. The regional differences were the main reasons for the differences in the carbon compensation rates of the planting industry. (2) The carbon compensation rate of the planting industry in China increased annually, and the number of provinces with high carbon compensation rates increased. The provincial difference in carbon compensation rate first decreased and then increased. The carbon compensation rate in the eastern provinces increased gradually, and the inter-provincial absolute gap decreased, changing from polarization to unipolarization. The carbon compensation rate in the central provinces increased gradually, and the absolute gap decreased. The carbon compensation rate in the western provinces was relatively stable and showed little change. (3) There was no σ-convergence in the carbon compensation rate of the planting industry in the whole country and the eastern and western regions, but it was not obviously observed in the central region. The absolute and conditional β-convergences were significant in the whole country and the eastern, central, and western regions. The results of this study emphasize that regional heterogeneity in the carbon compensation rate of China’s planting industry is prominent and that the temporal trend of carbon compensation rate is generally increasing. The “catch-up effect” among provinces and the convergence trend of the carbon compensation rate growth among regions are apparent. In the future, it will be important to improve the carbon compensation rate of the planting industry to better formulate a green development strategy for regional agriculture and actively reduce regional emissions.
Effects of different water and nitrogen management on ammonia volatilization in pear orchard soil
XING Hanbing, DONG Wenxu, PANG Guibin, HU Chunsheng
 doi: 10.13930/j.cnki.cjea.210133
Abstract(26) HTML(1) PDF(12)
Before the pear tree fertilization and management of blind and extensive, resulting in fertilizer waste and ecological environment and other problems.Making full use of soil water and fertilizer to improve crop yield is the long-term goal of farmland managers.In this paper, the changes of soil ammonia volatilization rate, loss and physical and chemical properties under different water and nitrogen management in pear topdressing period were analyzed by dynamic box method in orchard demonstration base of Jinzhou City, Hebei Province from March to September 2019.The experiment set up 5 treatments: blank (CK), surface spraying conventional irrigation (BW1), injection fertilization routine irrigation (IW1), surface spraying water saving irrigation (BW2), injection fertilization water saving irrigation (IW2).The volatilization of ammonia in each treatment was the most severe in the first 4 d. The two treatments (BW1、BW2) were especially severe. The peak variation range was 1.5−7.5 kg·hm−2·d−1, while the two injection treatments (IW1、IW2) changed steadily with time. The peak range was 0.1−5 kg·hm−2·d−1.The volatile loss of ammonia BW1、IW1、BW2、IW2 treatment was 24.05 kg·hm−2, 8.43 kg·hm−2, 31.94 kg·hm−2and 14.06 kg·hm−2, compared with BW1 (traditional management), and the emission reduction rates of injection fertilization (IW1 and IW2) was 64.95% and 41.54%, respectively. Ammonia volatilization was significantly affected by irrigation amount, and rhizosphere injection fertilization could significantly reduce ammonia volatilization emission and was less affected by irrigation amount.The correlation analysis showed that ammonia volatilization was positively correlated with the content of ammonium nitrogen and soil pH, but negatively correlated with the content of nitrate nitrogen, and the correlation between ammonium nitrogen and nitrate nitrogen was extremely significant (P<0.01). Soil moisture was positively correlated with ammonium nitrogen at a significant level (P<0.01).Compared with traditional management methods, the combination of rhizosphere injection fertilization and water-saving irrigation is one of the effective ways to reduce nitrogen loss in orchards.
Agroecosystem and Its Management
Impact of rice field management on the spider community characteristics in Taihu Lake Basin
MAN Jiyong, YUAN Kai, CHEN Baoxiong, WANG Zirui, LIU Yunhui
2021, 29(9): 1467-1479.   doi: 10.13930/j.cnki.cjea.210081
Abstract(191) HTML(22) PDF(21)
Spiders are important natural enemies that provide a key biological control service in rice planting systems. In recent decades, agricultural intensification has caused a series of environmental problems, including the loss of biodiversity and the decline of associated ecosystem services. Therefore, it is necessary to explore if the spider diversity can be improved by adjusting the rice farming practices to enhance the biological control services to allow more sustainable agricultural production. Recent studies on rice field spiders have compared the spider diversity between organic and conventional farming systems. However, studies on spider diversity in green rice fields are rare. The Taihu Lake Basin is an important rice production area in China, but it has also suffered from serious non-point pollution in recent years. Thus, it is important to develop a sustainable rice production approach and conserve the biodiversity and associated ecosystem services for regional sustainability. In this study, we sampled spiders with a suction sampler to assess the impact of different farming practices, including organic, green, and conventional farming practices, on the diversity, composition, and dynamics of spiders in rice fields. The results indicated that 1) there were significant differences in the spider diversity among different farming systems. Species richness, abundance, and the Simpson diversity index of spiders in organic rice fields were significantly higher than those in the other two treatments. 2) There were no significant differences in spider body size and the ballooning capacity among different farming practices. 3) The composition of spider communities in organic rice fields was distinct from that in conventional rice fields, whereas green rice fields had a similar spider composition as that of conventional and organic rice fields. 4) Organic and green rice fields were dominated by web-building spiders, whereas conventional rice fields were dominated by hunting spiders. 5) Organic rice fields had many indicator species, such as Bianor incitatus, Chrysso octomaculata, and Clubiona corrugata, while the spider communities in green and conventional rice fields were dominated by generalist and common species and lacked endemic species. 6) The spider community diversity in rice fields changed with rice growth. The species richness and Simpson diversity indexes of the spider communities were greater in organic rice fields than those in conventional and green rice fields across all rice-growing seasons, except during the early tillering and elongation stages. In summary, compared with conventional and green farming systems, organic farming system sustains greater spider diversity and distinct spider compositions with more web-building and indicator species. The spider diversity under green farming system, on the other hand, did not differ from that under conventional rice practices. To improve spider diversity and the associated biological control services in rice fields, the transformation of conventional rice production to organic production and reduced chemical reagents input should be encouraged, which is also important for the ecological restoration of the Taihu Lake Basin.
Assessment of the annual greenhouse gases emissions under different rice-based cropping systems in Hubei Province based on the denitrification-decomposition (DNDC) model
WU Mengqin, LI Chengfang, SHENG Feng, FENG Junheng, HU Quanyi, CHEN Yukun, ZHOU Haozhi, LIU Tianqi
2021, 29(9): 1480-1492.   doi: 10.13930/j.cnki.cjea.210099
Abstract(37) HTML(5) PDF(17)
This study explored the impacts of different management measures on the annual emissions of methane (CH4) and nitrous oxide (N2O) from the main rice-based cropping systems in Hubei Province using the denitrification-decomposition (DNDC) model and observed emission data to estimate the annual greenhouse gas emissions via a geographic information system (ArcGIS). In 2019, rice–wheat (RW) and rice–ratoon rice (RO) cropping systems were implemented in Zaoyang City of Northwest Hubei, RO and rice–oilseed rape (RR) cropping systems were implemented in Wuxue City of Southeast Hubei, and RW, RO, and RR cropping systems were implemented in Qianjiang City of the Jianghan Plain. There were two cultivation modes for each rice-based system: conventional cultivation and optimized cultivation. The optimized mode included deep application of nitrogen fertilizer, water-saving irrigation, and straw returning to the field. The annual fluxes of CH4 and N2O were measured using the static closed chamber method. The field validation results showed that the normalized root mean square error between the observed and simulated values of CH4 and N2O emissions ranged from 19.3% to 24.2% under different rice-based cropping systems with different management practices, and the degree of model fitting was acceptable. According to the simulation results of the DNDC model, the global warming potential (GWP) for the rice growing regions in Hubei Province followed the order of Jianghan Plain > Southeast Hubei > Northwest Hubei, and the annual cumulative emissions of CH4, N2O, and GWP under different rice-based cropping systems in different regions was in the order of RW > RO > RR. The cultivation modes significantly affected the CH4 and N2O emissions. Compared with conventional cultivation, optimized cultivation lowered the CH4 emissions per unit area by 9.5%–18.0%, 7.3%–18.4%, and 18.2%–22.4% under RW, RO, and RR, respectively. The N2O emissions lowered by 4.2%–14.2%, 6.9%–24.7%, and 8.8%–18.1%, respectively. Moreover, compared with conventional cultivation, optimized cultivation decreased the annual cumulative CH4 emissions by 11.8%, 14.4%, and 16.3% in Northwest Hubei, Southeast Hubei, and the Jianghan Plain, respectively, and decreased the annual cumulative N2O emissions by 82.4%, 77.5%, and 83.0%, respectively. Under optimized cultivation, the GWP for Northwest Hubei was in the order of Xiangyang > Shiyan > Shennongjia, that for Southeast Hubei was in the order Huanggang > Xianning > Wuhan > Huangshi > Ezhou, and that for the Jianghan Plain was in the order Jingzhou > Jingmen > Xiaogan > Suizhou > Tianmen > Xiantao > Qianjiang. Our results show that the DNDC model can suitably simulate the greenhouse gas emissions of different rice-based cropping systems in Hubei Province. An optimized cultivation mode is needed to mitigate greenhouse gas emissions during rice production in Hubei Province.
Crop Cultivation and Physiological Ecology
Effects of rotational pattern and fertilization application on soybean yield under straws returning of preceding crop
ZHANG Guowei, WANG Xiaojing, YANG Changqin, SHU Hongmei, LIU Ruixian
2021, 29(9): 1493-1501.   doi: 10.13930/j.cnki.cjea.210084
Abstract(57) HTML(1) PDF(28)
Field experiments were conducted from 2018 to 2020 at the Soybean Experimental Station of the Jiangsu Academy of Agricultural Sciences in Nanjing, Jiangsu Province. A split-plot design was used to study the effects of straw returning and fertilizer application on the nutrient utilization and yield of soybeans under different rotation patterns. The main plot factor was different rotation patterns with straw returning of preceding crop of soybean (wheat–soybean, garlic–soybean, leaf mustard–soybean, and winter fallow–soybean), while the sub-plot factor was fertilizer application (no fertilizer and nitrogen [N], phosphorus [P], and potassium [K] compound fertilizer [15∶15∶15] at 225 kg∙hm−2). The results showed that rotation pattern and fertilization application significantly affected the soybean yield and yield components under crop straw returning of preceding crop, and the two factors had significant interactive effects on the yield, yield components, plant morphological index, biomass, nitrogen accumulation and distribution, and disease rate of soybean, as well as soil total nitrogen, available nitrogen contents. Compared with the winter fallow–soybean planting pattern, the other three rotation patterns decreased soil bulk density and available nitrogen content but increased soil organic matter and total nitrogen contents. Plant height, stem diameter, height of the bottom pod, branch number per plant, total biomass, grain biomass, total nitrogen accumulation, and grain nitrogen accumulation were the highest under garlic–soybean and leaf mustard–soybean rotation patterns, which were beneficial for yield. The final yield increased by 4.40%–10.30% and 5.66%–7.09% under fertilization treatments and by 4.88%–8.23% and 2.19%–8.78% under no fertilization treatments compared to the winter fallow–soybean planting pattern, respectively. The wheat–soybean rotation pattern inhibited soybean plant growth, and the total biomass, grain biomass, total nitrogen accumulation, and grain nitrogen accumulation were the lowest. The harvest index of biomass and nitrogen and the nitrogen production efficiency were the highest, but the yield was the lowest in this case, decreasing by 2.80–7.30% in the fertilizer treatments and by 7.45%–11.18% in the no fertilizer treatment compared to the winter fallow–soybean planting pattern. Wheat straw returning increased the diseased plant rate, whereas the leaf mustard–soybean and garlic–soybean rotations decreased the rate of diseased plants. Compound fertilizer application promoted plant growth, reduced the rate of diseased plants, improved soil total nitrogen and available nitrogen contents, soybean biomass and nitrogen accumulation, and harvest density. Although harvest index and nitrogen use efficiency of soybean were low, the yield significantly increased. Compared with the no fertilizer application treatment, fertilizer application increased the soybean yields of the garlic–soybean, leaf mustard–soybean, and wheat–soybean rotations by 9.21%–13.01%, 7.97%–14.02%, and 15.00%–15.91%, respectively. Therefore, the garlic–soybean and leaf mustard–soybean rotation modes should be popularized. Under a wheat–soybean rotation pattern, high yield is achieved when wheat straw is returned to the field. In the wheat–soybean rotation, fertilizers must be applied after wheat straw is returned to the field to achieve high yield.
Effects of the irrigation quota and drip irrigation pipes spacing on growth and development of summer maize with subsurface drip irrigation
YAO Jiawei, QI Yongqing, LI Huaihui, SHEN Yanjun
2021, 29(9): 1502-1511.   doi: 10.13930/j.cnki.cjea.210058
Abstract(23) HTML(1) PDF(15)
Water and soil resources in the North China Plain are mismatched. Traditional flood irrigation methods in this area have low water resource utilization and lead to serious water loss, which has caused a rapid decrease in groundwater levels. This study aims to improve the efficiency of irrigation water use in this area, determine the influence of subsurface drip irrigation on the field-scale water balance, and explore the effects of different irrigation amounts and drip irrigation zone spacing on the growth and water consumption of summer maize under subsurface drip irrigation conditions. Field experiments with two irrigation quotas (62 and 35 mm) and three drip irrigation pipes spacings (60, 80, and 100 cm) were conducted with the conventional flood irrigation as the control in farmlands in the North China Plain to analyze their effects on the growth and development, yield and irrigation water use efficiency of summer maize, and the soil profile moisture distribution, evapotranspiration, evaporation. Soil evaporation under subsurface drip irrigation was measured and compared using a microlysimeter. The results showed that irrigation water from subsurface drip irrigation mainly stayed in the 20–60 cm soil layer, and the wetted body presented a “small up and large down” form. The higher the irrigation amount, the larger the wetted body range, and the larger the soil volumetric water content. Compared to flood irrigation, the soil moisture contents of the 0–20 cm and 60–100 cm soil layers from subsurface drip irrigation were relatively low, and a dry soil layer formed at about 0–10 cm layer, which reduced soil evaporation. Maize plant height, leaf area index, and dry matter accumulation increased with increasing amounts of subsurface drip irrigation. Under flood irrigation, the maize plant height increased faster, and the accumulation rate of the maximum dry matter was higher compared to subsurface drip irrigation. Low amounts of subsurface drip irrigation delayed maize growth. When the irrigation amount was reduced by 22%, maize yield under subsurface drip irrigation did not differ from maize yield under traditional flood irrigation. Compared to flood irrigation, subsurface drip irrigation reduced soil evaporation by 30%, evapotranspiration by 8%, the E/ET value from 0.34 to 0.27; and increased the irrigation water use efficiency by 20%, the harvest index by 10%. The different drip irrigation zone spacing treatments had no effect on the growth and water consumption of maize. For high maize growth and yield, efficient irrigation water use, and cost-effective investments in drip irrigation equipment, the optimal irrigation quota was 62 mm with a drip irrigation zone spacing of 100 cm.
Optimal nitrogen application rate for winter wheat under multi-objective constraints in the North China Plain
DAI Na, SHI Wenjiao, SHI Xiaoli
2021, 29(9): 1512-1523.   doi: 10.13930/j.cnki.cjea.210107
Abstract(20) HTML(2) PDF(16)
The oversupply of nitrogen fertilizers has caused serious environmental problems, such as water pollution, destruction of soil structure, and global warming. Thus, the optimal nitrogen application rate of winter wheat should consider the environmental impacts. Many attempts have been made to evaluate the optimal winter wheat nitrogen application rate using different indicators, such as yield, nitrogen use efficiency, and nitrogen uptake. However, previous studies have only focused on economic benefits and did not consider the ecological benefits. Furthermore, the optimal nitrogen application rates have been evaluated with individual indicators; a systematic approach that integrates these indicators has not yet been presented. To better understand the optimal nitrogen application rate for winter wheat under multi-objective constraints in the North China Plain, this study used the daily meteorological data, observation data of the phenology, and the yield of winter wheat at nine stations (Tangshan, Huanghua, Luancheng, Huimin, Nangong, Ganyu, Shangqiu, Zhumadian, and Shouxian) from 1981 to 2017, to simulate five indicators of the economic and environmental benefits of the winter wheat (yield, nitrogen partial factor productivity, nitrogen uptake, the balance between yield increase and nitrogen saving, and environmental-economic benefits) by using the crop estimation through resource and environment synthesis (CERES)-Wheat model. The relationship between each indicator and the nitrogen application rate was investigated to determine the optimal nitrogen application rates under different constraints. Finally, the comprehensive optimal nitrogen application rate was determined according to the economic and ecological benefits. The results indicated that the optimal nitrogen application rates varied across stations and objective constraints. The average value of the optimal nitrogen application rate for the nine stations from high to low were that constrained by nitrogen uptake (363 kg∙hm−2), yield (257 kg∙hm−2), environment-economic benefits (190 kg∙hm−2), the balance between yield increase and nitrogen saving (173 kg∙hm−2) and nitrogen partial factor productivity (30 kg∙hm−2). The optimal nitrogen application rates under the constraints of the balance between yield increase and nitrogen-saving and environmental-economic benefits were 173 kg∙hm−2 and 190 kg∙hm−2, respectively. This indicates a reduction by approximately 20%−30% of the nitrogen application rates for constraints related to yield maximization, and reductions by 47% and 42% compared to the actual nitrogen application rates of farmers in the North China Plain. Thus, the environmental damage caused by nitrogen fertilizers can be minimized under these constraints. Meanwhile, approximately 90% of the wheat yield can be obtained with these optimal nitrogen application rates, and economic and ecological benefits can be simultaneously guaranteed. To secure grain production and minimize environmental impacts, the optimal nitrogen application rates under the constraints of the balance between yield increase and nitrogen-saving and environmental-economic benefits can be regarded as the regional reference for winter wheat planting in the North China Plain. The regional reference of the optimal nitrogen application rates for winter wheat varied with zones, it was 150 kg∙hm−2 in the piedmont plains of Taihang Mountain and Yanshan Mountain, and 170 kg∙hm−2 in the Nanyang Basin. For the winter wheat in the Shandong Peninsula and the plains around Bohai Sea, the optimal nitrogen application rate was higher (200 kg∙hm−2), and in the Haihe Plain, the optimal nitrogen application rate was 225 kg∙hm−2.
Changes of maize lodging resistance after physiological maturity and its influencing factors in Sichuan
CHEN Xiang, LI Xiaolong, DU Xia, LIU Jiayuan, LIU Qianqian, YUAN Jichao, KONG Fanlei
2021, 29(9): 1524-1532.   doi: 10.13930/j.cnki.cjea.210044
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Densification planting and delayed harvesting are important measures for the promotion and development of mechanized grain harvesting technology of maize, but they also reduce the lodging resistance of stalks and increase the risk of lodging. The appearance of maize lodging not only increases the difficulty of mechanical harvesting and reduces the speed of mechanical harvesting, but also increases the loss of ear caused by lodging and reduces the yield of mechanical grain harvest. Therefore, the purpose of this experiment was to explore the changing law of the lodging resistance ability of maize stalks after physiological maturity under different densities and to provide a scientific basis for the development of maize dense planting and high-yielding mechanical grain harvest technology. This experiment used ‘Zhenghong 6’ as the material and set 6 density treatments: 3.0×104 plants∙hm−2 (B1), 4.5×104 plants∙hm−2 (B2), 6.0×104 plants∙hm−2 (B3), 7.5×104 plants∙hm−2 (B4), 9.0×104 plants∙hm−2 (B5), and 10.5×104 plants∙hm−2 (B6). In the physiological maturity period (August 6, A1), 11 d after physiological maturity (August 17, A2), 22 d after physiological maturity (August 28, A3), and 35 d after physiological maturity (September 10, A4), 5 plants in each plot were sampled and the changing laws of stalk strength, internode morphology, internode dry matter, moisture content, etc. were determined. The results showed that the internode stalk strength of maize decreased after physiological maturity, but the decreasing range gradually reduced with time. After physiological maturity, the dry weight per unit length and water content of stalk decreased, while the internode length-to-diameter ratio increased slightly. Stalk strength and it’s change with time were significantly different among different densities after physiological maturation. In the density range of 4.5×104 plants∙hm−2 to 10.5×104 plants∙hm−2, the decreased amplitude of stalk strength showed a decreasing trend with the increase of density, and that of stalk strength of low density was greater than that of high density. The increase in planting density resulted in a significant decrease in stalk dry weight per unit length and a significant increase in the internode length-to-diameter ratio. The results showed that the decrease of stalk dry weight per unit length after physiological maturity was the main reason for the decrease of stalk strength. The increase of planting density significantly reduced the stalk strength, and with the extension of standing time, the stalk strength further decreased. The stalk strength of different densities decreased differently, and the decrease rate of low density was greater, but the stalk strength of high density was still lower than that of low density treatment all the time. Therefore, properly dense planting and harvest at the right time can reduce the risk of lodging caused by the decline of the standing capacity of culms after physiological maturity of maize.
Response of fine roots of apple to plastic film mulching in the dry tableland of eastern Gansu
SUN Wentai, MA Ming, DONG Tie, NIU Junqiang, YIN Xiaoning, LIU Xinglu
2021, 29(9): 1533-1545.   doi: 10.13930/j.cnki.cjea.210071
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This study investigated the annual growth dynamics of apple tree roots in the dry plateau of Longdong and the temporal and spatial differences in the number, morphology, branching characteristics of the roots, and soil physical and chemical properties in vertical soil layers under film mulching and soil moisture conservation measures. Eighteenth-year-old apple trees (‘ Nagano Fuji No.2’) were assessed three times in the rooting peak times of apple tree: from spring sprouting to vigorous growth of new shoots (Ⅰ), shoots stopped growing (Ⅱ), and from fruit harvest to defoliation (Ⅲ). Using the soil profile and stratified sampling method, different treatments (conventional tillage [CK], film-mulching for two years [2Y], film-mulching for four years [4Y], and film-mulching for six years [6Y]) were investigated to analyze the spatial distribution of biomass, root length, surface area, specific root length, and the specific branch (branch number/dry matter weigh) of roots. Regression analysis was used to assess the fine root growth strategy for apple trees with plastic film mulching. The results showed that the rooting peak Ⅲ was the most important stage of the annual growth cycle of apple roots. The fine roots biomass at rooting peak Ⅲ under each treatment was 73.55%–84.85% of the total biomass at the three rooting peaks. The number of fine root branches at rooting peak Ⅰ in the surface soil (0–20 cm) was 130.67%, 100.53%, 156.63%, and 238.63% of that at rooting peak Ⅲ, which effectively improved the utilization of the soil resources in situ. At rooting peak Ⅲ, CK promoted the distribution of fine root length and root surface area in the surface soil, which were 275.64% and 248.96% of those at rooting peak Ⅰ, respectively. The number of branches and specific branches were only 76.53% and 14.68% of those at rooting peak Ⅰ, which expanded the effective nutrient space and reduced the internal competition of the root system. The soil water content in the short-term mulching (2Y) treatment in each soil layer were 112.39% (0−20 cm), 118.04% (20−40 cm), 124.06% (40−60 cm), 133.59% (60−80 cm), and 114.49% (80−100 cm) of CK; and the fine root biomass was 116.72%, 232.35%, and 112.09% of CK at the three rooting peak times. Compared with CK, the specific root length of the surface fine roots increased by 47.1% and 62.92% at rooting peaks Ⅰ and Ⅲ, and the root surface area increased by 67.21% and 56.88% in 2Y treatment. The number of fine root branches in the deep soil (80–100 cm) increased by 282.22% and 7.27%, respectively, compared with CK. The 2Y treatment promoted fine root morphological trait expression at the surface soil and branch structure establishment in the deep soil. Fine roots were evenly distributed in the 0–100 cm vertical soil layer and 0–120 cm horizontally from tree. Compared with CK, the 6Y treatment increased the number of fine root branches and specific branches by 6.11% and 34.6%, respectively, in the early growth stage, but by 58.1% and 19.56% in the late growth stage. These results demonstrate the characteristics of complex branches in the early growth stage and simplified branches in the late growth stage significantly inhibit the growth of fine roots at rooting peak Ⅲ. The fine root length, root surface area, and specific root length in the deep soil were 35.19%, 40.43%, and 82.67% of those of CK, respectively, in 6Y treatment. Fine root growth was affected by the phenological period and the turnover of tree nutrients; the “conservatively obtaining resources” growth strategy was applied in the early growth stage, and the “rapidly obtaining resources” growth strategy was adopted in the late growth stage. Short-term film mulching (2Y) can improve the physical and chemical properties of the soil and promote fine root extension. Damage from long-term plastic film mulching (6Y) to the subsurface soil (20–40 cm) prevented the fine roots from settling down and they became concentrated in the surface layer.
Agricultural Resources and Environment
Nitrate storage and leaching in the critical zone of farmland in the North China Plain
CHEN Xiaoru, LI Xiaoxin, HU Chunsheng, LEI Yuping, NI Rui, MA Lin
2021, 29(9): 1546-1557.   doi: 10.13930/j.cnki.cjea.210087
Abstract(34) HTML(2) PDF(20)
After the reform and opening in 1978, China’s nitrogen (N) fertilizer input increased sharply, increasing grain yield, but also causing serious soil nitrate accumulation and leaching problems that threaten groundwater security. This study aimed to explore the effects of N fertilizer input on nitrate storage in the vadose zone of farmlands (grain and vegetable fields) in the North China Plain (NCP) and to quantify the total amount of nitrate leaching from the 2–50 m underground aquifer of the NCP. We collected soil profiles from areas with different groundwater table depths (2–50 m) of the NCP farmlands and measured the nitrate content in different soil layers. Concurrently, data on N fertilizer input and changes in the farmlands of different provinces and counties of the NCP were collected from literatures and relevant websites for 42 years (1978–2019). Nitrate storage in the vadose zone was calculated using a geographic information system (GIS). The ratio of nitrate storage to nitrogen fertilizer input (NR) in the vadose zone was proposed from the perspective of regional blocks. The NR value of grain and vegetable fields in the NCP ranged from 0.14 to 0.39 and from 0.15 to 0.41, respectively. This provided scientific data and a theoretical basis for reducing the leaching loss of nitrate from the vadose zone to the aquifer. The relationship (NR value) between N fertilizer input and nitrate storage in the vadose zone at different groundwater table depths reflects the degree of influence of N fertilization on the amount of residual nitrate in the vadose zone. Moreover, under the same N fertilizer conditions, the leaching loss of nitrate from the NCP farmlands was estimated at groundwater table depths of 2–50 m. The results showed that high fertilizer application in the NCP farmlands led to large amounts of nitrate leaching into the vadose zone-aquifer system. The total nitrate leaching from grain and vegetable fields under 2 m of groundwater was 6.7565 and 1.9956 million tons, respectively, accounting for 13% and 14% of the total N fertilizer input from grain and vegetable fields in 42 years (1978–2019). Under ideal conditions (depth of vadose zone >10 m, the same farmland area and soil texture), higher N fertilizer input was associated with greater total nitrate storage in the vadose zone. Nitrate storage per unit area of farmland (grain and vegetable fields) in the NCP increased with increasing depth of the vadose zone at areas with 2–50 m of groundwater depth. This study also indicated that a thick vadose zone played an important role in nitrate nitrogen interception. In the 2, 3, 6, 10, 16, 25, 40, and 50 m vadose zones, grain field nitrate storage accounted for 14%, 18%, 26%, 30%, 33%, 35%, 38%, and 39% of the total N fertilizer input over 42 years (1978–2019), respectively. Vegetable field nitrate storage at the same depths of the vadose zone accounted for 15%, 20%, 28%, 32%, 34%, 36%, 40%, and 41% of the total N fertilizer input over 42 years (1978–2019), respectively. This study suggests that the relevant departments and agricultural workers should consider the depth of the vadose zone to comprehensively evaluate nitrate nitrogen accumulation and groundwater safety issues from a regional perspective.
Effects of tillage and straw returning method on the distribution of carbon and nitrogen in soil aggregates
ZHANG Yuming, HU Chunsheng, CHEN Suying, WANG Yuying, LI Xiaoxin, DONG Wenxu, LIU Xiuping, PEI Lin, ZHANG Hui
2021, 29(9): 1558-1570.   doi: 10.13930/j.cnki.cjea.200791
Abstract(38) HTML(4) PDF(16)
The North China Plain is a major grain production area in China, and wheat-maize rotation is the main cropping pattern in this region. Long-term straw returning and shallow rotary tillage have caused soil quality problems, such as a shallow plow soil layer, thickening of the plow bottom, and nutrient accumulation at the soil surface. These problems restrict a sustainable and stable grain yield. This study examined the effects of different agricultural management practices of tillage measures and methods of straw returning of physical protection on the soil aggregate composition and stability, the distribution of organic carbon and nitrogen in the aggregates at the Luancheng Agricultural Ecosystem Experimental Station, Chinese Academy of Sciences. A tillage and straw counters-field positioning experiment was conducted from 2016 with five treatments: no-straw and rotary tillage (as control 1, RT), straw mulching and rotary tillage (as control 2, SR), straw mulching and deep ploughing (SP), straw incorporated into 0−40 cm soil layer of 40 wild no-wheat planting belt (SID), and straw buried into 30−40 cm soil layer (SBD). The three latter treatments represented different straw returning methods. The results showed that changing rotary tillage to deep tillage under straw returning significantly increased the content of large macroaggregates (>0.25 mm). Different straw returning methods led to significantly different changes in water stability of the large (>2 mm) and small (0.25–2 mm) macroaggregates. Straw returning to the deep soil layer increased the content of large water-stable macroaggregates in soil layers below 10 cm (>2 mm), whereas increased the content of small water-stable macroaggregates (0.25–2 mm) in the surface layer. The changes in the water stability of large and small macroaggregates were impacted by the straw returning method. Straw returning to deep soil layer significantly increased the stability in the subsurface layer (20–40 cm) and decreased the structural fragmentation rate of soil aggregates. Deep straw returning effectively integrated the 0–40 cm soil layer, eliminated the surface accumulation of nutrients, and significantly increased the soil organic carbon and nitrogen contents in the subsurface layer and the contribution of large macroaggregates to soil organic carbon and nitrogen. The contribution of organic carbon and nitrogen of the macroaggregates (>2 mm) in the 20–40 cm soil layer was 42.2%–44.0% and 32.8%–49.9%, respectively, which increased by 48.7%–54.9% and 32.8%–101.8%, respectively, compared to straw-free rotary tillage. In summary, the straw returning to deep soil layer improved soil structure of tillage layer, promoted integration of soil layers and emilimated nutrient accumulation in soil surface layer.
Effect of fertilizer application on soil carbon loss in purple soil
SHEN Jiao, WANG Xiaoguo, MA Han
2021, 29(9): 1571-1581.   doi: 10.13930/j.cnki.cjea.210123
Abstract(28) HTML(3) PDF(7)
Studies on organic carbon gas exchange and runoff loss in farmland soil are relatively isolated, and the synergy between the two pathways is poorly understood. In this study, simultaneous tests of organic carbon gas exchange and soil–water interface migration process of purple soil under different fertilization treatments were conducted using a runoff plot that allowed interflow observation. The experimental treatments included no fertilizer (CK), chemical fertilizer (nitrogen, phosphorus, and potassium; NPK), pig manure plus synthetic NPK fertilizer (OMNPK), and the incorporation of crop residues plus synthetic NPK fertilizer (RSDNPK). The results showed that 1) the soil respiration rate and carbon dioxide (CO2) emission flux under different fertilization treatments were RSDNPK > OMNPK > NPK > CK, indicating that the application of chemical fertilizer, organic fertilizer, and straw returning increased the soil respiration rate of purple soil. The CO2 emission flux of RSDNPK was 4155.87 kg(C)∙hm−2, significantly higher than those of the other fertilization treatments. 2) The soil organic carbon runoff loss flux was in the order of RSDNPK > OMNPK > CK > NPK, and there were differences in the runoff loss pathways under different fertilization treatments. RSDNPK reduced sediment erosion and significantly increased the flux of dissolved organic carbon (DOC) loss in the interflow, reaching 8.29 kg(C)∙hm−2. The DOC loss flux of the interflow accounted for 49.82%–92.11% of the total runoff carbon loss flux under different fertilization treatments, indicating that interflow was the main pathway of soil organic carbon loss in purple soil. 3) The total fluxes of soil organic carbon loss under RSDNPK were significantly higher than those under other fertilization treatments, which was not significantly different between OMNPK and NPK. The proportion of CO2 emission fluxes to the total fluxes was more than 99% in each fertilization treatment, indicating that gaseous loss was the main mechanism of organic carbon loss in purple soil. 4) We calculated the carbon loss flux per unit yield for each fertilization treatment and combined the economic benefits with the ecological environmental load. The results showed that the carbon loss flux per unit yield in CK was significantly higher than that in other fertilization treatments. The soil organic carbon content of the OMNPK treatment was 5.86 g∙kg−1, greater than that of NPK, indicating that organic fertilizer application is beneficial to the accumulation of soil organic carbon. OMNPK should thus be prioritized in the purple soil area.
Effects of wheat straw and nitrogen fertilizer application on the soil microbial biomass carbon and nitrogen in the rhizosphere of rice
LUO Jialin, ZHAO Yahui, YU Jianguang, WANG Ning, XUE Lihong, YANG Linzhang
2021, 29(9): 1582-1591.   doi: 10.13930/j.cnki.cjea.201019
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Soil microbial biomass carbon and nitrogen (SMBC and SMBN, respectively) are key factors that characterize soil fertility and its’ change. The rhizosphere is a hotspot of microbial interactions in rice fields. Rhizosphere microbiota are important for rhizosphere ecology and are the impetus of soil organic matter and nutrient transformation. This study investigated bulk and rhizosphere SMBC and SMBN in paddy soils in response to wheat straw addition and different amounts of nitrogen fertilizer application in the typical rice and wheat rotation areas of the middle and lower reaches of the Yangtze River. There were four treatments (in triplicate): no straw or nitrogen fertilizer (CK), straw addition (SN0), straw and low nitrogen fertilizer addition (SN1), and straw and high nitrogen fertilizer addition (SN2). The results showed that, compared to CK, the SMBC contents in the SN0 rhizosphere and bulk of high sandy soil increased by 40.3% and 48.1%, respectively, while those in yellow mud soil increased by 95.7% and 75.4%, respectively. The SMBN contents in the rhizosphere of high sandy soil did not change significantly, but decreased by 19.9% in bulk soil. The SMBN contents in the rhizosphere and bulk of SN0-treated yellow mud soil decreased by 19.5% and 49.0%, respectively. Low nitrogen fertilizer application significantly increased the SMBC content in the rhizosphere of sandy soil and the bulk of yellow mud soil and increased the SMBN content in the rhizosphere and bulk of both soils. With increased nitrogen fertilizer application, SMBC and SMBN contents in the rhizosphere and bulk of both soils significantly increased. Compared with SN0, the SMBC content in the rhizosphere of SN1 in sandy soil increased by 5.1%, that in bulk decreased by 12.9%, and that in the bulk of yellow mud soil increased by 11.1%. There was no significant change in SMBC content in the rhizosphere of yellow mud soil. SN1 treatment led to an increase in the SMBN contents of the rhizosphere and bulk of sandy soil by 17.3% and 9.8%, respectively, and an increase in the SMBN contents of the rhizosphere and bulk of yellow mud by 36.1% and 68.9%, respectively. SN2 treatment led to an increase in the SMBC content in the sandy soil rhizosphere and bulk by 8.6% and 39.3%, respectively, and by 34.58% and 3.05% in yellow mud, respectively, over those of SN0. For the SN2 treatment, sandy soil rhizosphere and bulk SMBN increased by 27.0% and 13.5%, respectively, and they increased by 25.6% and 232.9%, respectively, in yellow mud soil, compared with SN0. These comprehensive analyses show that nitrogen fertilizer addition can increase the SMBC and SMBN contents in bulk and rhizosphere soils, thereby improving soil nutrient availability. Straw returning with nitrogen fertilizer greatly improves soil fertility and promotes crop growth in the rice-wheat rotation areas of the middle and lower reaches of the Yangtze River.
Effects of tobacco stalk biochar-based fertilizer on the organic carbon fractions and microbial community structure of adlay soil
HU Kun, ZHANG Hongxue, GUO Liming, WU Fengying, ZHOU Biqing, XING Shihe, MAO Yanling
2021, 29(9): 1592-1603.   doi: 10.13930/j.cnki.cjea.210127
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Long-term continuous cropping of adlay ( Coix lacryma-jobi L.) and the indiscriminate application of chemical fertilizers have led to soil fertility declines and acidification. To explore the effects of tobacco stalk biochar-based fertilizer on the soil organic carbon (SOC) fractions and microbial community structure and abundance, tobacco stalk biochar-based fertilizer was used in a field experiment with four treatments: no fertilizer, conventional fertilizer, low tobacco stalk biochar-based fertilizer, and high tobacco stalk biochar-based fertilizer. Changes in the activities of four enzymes related to soil carbon cycling and microbial activity were evaluated, and the relationships between the soil pH, SOC fractions, soil enzymes, and soil bacterial abundance were analyzed. The results showed that: 1) The application of tobacco stalk carbon-based fertilizer significantly increased the soil pH and the contents of SOC, dissolved organic carbon (DOC), particulate organic carbon (POC), and microbial biomass carbon (MBC) (P<0.05). The MBC was most affected, increasing by 41.09%−76.04% compared to conventional fertilizer application. 2) The application of tobacco stalk biochar-based fertilizer significantly increased the activities of soil amylase and dehydrogenase (P<0.05). Compared to conventional chemical fertilizers, amylase and dehydrogenase activities increased by 44.28% and 57.54%, respectively, whereas the soil invertase activity was unaffected when tobacco stalk biochar-based fertilizer was applied. 3) The application of tobacco stalk biochar-based fertilizer increased the Chao1 and Shannon indexes, abundance and diversity of the soil bacterial communities. 4) The application of tobacco stalk biochar-based fertilizer affected the composition and structure of the soil bacterial community, increased the relative abundance of Actinomycetes and Bacteroides, and reduced the relative abundance of Proteobacteria and Chloroflexus. It also significantly increased the abundance of Nitrospira, Bryobacter, and other bacterial genera, and significantly reduced the abundance of Aciditerrimonas and Crenothrix. 5) Redundancy anaylsis showed that soil pH, carbon fraction, soil enzymes activities, and soil bacterial community abundance were correlated each other after the application of tobacco stalk biochar-based fertilizer; soil pH, SOC, POC, DOC, MBC were significantly positively correlated with the activities of various soil enzymes (P<0.05), but were significantly negatively correlated with Proteobacteria (P<0.05). In summary, tobacco stalk biochar-based fertilizer increased the soil pH, SOC fractions, soil enzymes activities, and soil bacterial abundance, which improved the soil bacterial community structure and the adlay planting soil and optimized the soil ecology. This study provides a reference for the resource utilization of tobacco stalk and improvements in soil fertility.
Influence of intercropping Sedum plumbizincicola with Capsicum annum on the migration and availability of soil cadmium
WANG Gaofei, ZHOU Peng, WANG Yongping, WANG Yan, LIN Shan, XING Dan
2021, 29(9): 1604-1614.   doi: 10.13930/j.cnki.cjea.210038
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A field experiment was conducted in Xinpu New District, Zunyi City, Guizhou Province, in 2019 to explore the effects of different Sedum plumbizincicola intercropping patterns on the migration and availability of cadmium (Cd) in the soil around the roots of Capsicum annum. Five planting patterns were established: monoculture S. plumbizincicola, monoculture C. annum, stripe intercropping of C. annum with S. plumbizincicola (JZ1), cross intercropping of C. annum with S. plumbizincicola (JZ2), and mixed intercropping of C. annum with S. plumbizincicola (JZ3). Soil samples were collected around the C. annum roots at harvest, and the Cd content, soil pH, organic matter content, and contents of total and available nitrogen (N), phosphorus (P), potassium (K), and content of glomalin (GRSP) were measured and analyzed. The results showed that, compared to C. annum monoculture, the contents of acid-soluble Cd and reducible Cd in the soil around the C. annum roots effectively decreased by 39.6% and 23.9% in the cross intercropping system with S. plumbizincicola, and 41.5% and 29.0% in mixed intercropping system with S. plumbizincicola, respectively. The risks of soil Cd migration and availability were also reduced. Stripe intercropping C. annum with S. plumbizincicola had no effect on Cd mobility and availability in the soil around the C. annum root system. The Cd migration of the crossing intercropping and mixed intercropping systems decreased by 25.8% and 34.2%, respectively, and the Cd availability decreased by 11.6% and 26.9%, respectively. The stripe, cross and mixed intercropping systems did not affect the contents of Cd in oxidizable and residual states, but significantly increased the content of easily extracted GRSP in the soil by 24.5%, 39.9%, and 40.6%, respectively. Cross intercropping C. annum with S. plumbizincicola and mixed intercropping treatments also significantly increased the total soil GRSP content by 51.7% and 86.7%, respectively. Redundancy analysis showed that the importance of the soil environmental factors on soil Cd migration and availability followed the order: total extracted GRSP > available potassium > pH > easily extractable GRSP > total potassium > total phosphorus > total nitrogen > alkaline hydrolyzed nitrogen > available phosphorus > organic matter. The extractable GRSP and available potassium from the soil were the key regulatory factors affecting soil Cd migration and availability. In summary, intercropping with S. plumbizincicola significantly reduced the risks of Cd migration and availability in the soil around the C. annum roots, and the effects of cross and mixed intercropping were better than that of stripe intercropping. These results provide a theoretical basis for better usage of farmland with low to medium levels of Cd.
Effects of winter crops on the earthworm yield and earthworm cast in paddy fields
LI Chao, ZHAO Yang, GUO Lijun, CHENG Kaikai, TANG Haiming, HUANG Min, TANG Wenguang, WEN Li, WANG Ke, CUI Ting, XIAO Xiaoping
2021, 29(9): 1615-1624.   doi: 10.13930/j.cnki.cjea.200821
Abstract(22) HTML(0) PDF(3)
There is a large market demand for earthworms; thus, earthworm breeding will increase in the future. However, artificial earthworm breeding faces many problems, such as large labor input, high breeding costs, and difficulty in large-scale breeding. Increased earthworm production by planting winter crops may be an effective way to solve these problems. This study incorporated a field investigation and rainfall and accumulated temperature data from 2017 to 2020 to investigate the effects of different winter crops, including fallow (T1), milk vetch (T2), and rapeseed (T3), on the yield and cast of Pheretima guillelmi to provide theoretical and technical support for earthworm production in paddy fields. The results showed that the coefficient of variation (CV) of earthworm yield in different years was positively correlated with the CV of winter crops yield (P<0.01). Continuous rainfall from October to December and low temperatures from December to February from 2018 to 2019 led to a significant decrease in the yields of winter crops and earthworms. The soil organic matter content (average value under three yield levels) was in the order of rapeseed > milk vetch > fallow, and the earthworm yield and earthworm manure yield were significantly positively correlated with the soil organic matter content (P<0.05) and with winter crop yield. The earthworm individuals number per m2 of fallow, milk vetch, and rapeseed was 8.4−12.8, 11.2−30.8, and 20.4−49.1, respectively, the average earthworm individuals number per m2 was 10.8, 20.7 and 36.3, respectively. The earthworm yield was 290−428 kg·hm−2, 368−1054 kg·hm−2, and 763−1845 kg·hm−2, respectively, and the average earthworm yield were 373 kg·hm−2, 695 kg·hm−2, and 1364 kg·hm−2, respectively. The earthworm cast yield was 1921−3126 kg·hm−2, 3023−10 116 kg·hm−2, and 6034−18 958 kg·hm−2, respectively, and with the averages of 2652 kg·hm−2, 6438 kg·hm−2, and 12 545 kg·hm−2, respectively. The averages were in the order of rapeseed > milk vetch > fallow. The ratio of cast weight to fresh earthworm weight increased with increasing winter crop yield, with an average value of 8.8; the average values for fallow, milk vetch, and rapeseed were 7.1, 9.1, and 9.0, respectively. Variation in earthworm yield and earthworm cast yield between different yield levels of rapeseed was less than that of milk vetch, indicating that rapeseed was beneficial for higher yield stability for earthworms and earthworm casts. In summary, the yield of earthworms and casts was greatly disturbed by rainfall and accumulated temperature, and the high-yield fields of winter crops had high soil organic matter content, which was conducive to increasing the yields of earthworms and earthworm casts and increasing their stability. Planting rapeseed also had a beneficial effect.
Agricultural Ecologic Economics and Ecoagriculture
Analysis of the mediation effect of urbanization on non-point source pollution from the planting industry
LUO Haiping, HE Zhiwen, HU Xueying
2021, 29(9): 1625-1635.   doi: 10.13930/j.cnki.cjea.210033
Abstract(23) HTML(2) PDF(13)
In the light of continued urbanization, it is important to analyze the effect of urbanization on fertilizer non-point source pollution in China to alleviate ecological pressure and promote green and high-quality agriculture development. This study used the unit survey and assessment method to measure the total emissions and emission intensity of fertilizer non-point source pollution in 31 provinces (cities, autonomous regions) in China from 2008 to 2018. The mediation effect model was used to analyze the influence of urbanization on fertilizer non-point source pollution. Compared with existing studies, this study has two aims. The first is to analyze the influence of urbanization on fertilizer non-point source pollution via the mediation effect, and to clarify the mechanism of how urbanization affects fertilizer non-point source pollution. The second is to analyze the spatial heterogeneity in the impact of urbanization on the fertilizer non-point source pollution in grain function areas, e.g., differences in the mechanisms of various mediation factors in different grain function areas. Our empirical results showed that: 1) from 2008 to 2018, fertilizer non-point source pollution in China had an inverted “U” pattern, first increasing and then decreasing, with 2015 as the inflection point. The total amount and intensity of emissions fell to the lowest levels at the end of the study period, 5.16 million t and 37.65 kg·hm−2, respectively. 2) On a national level, urbanization had a mediating effect on fertilizer non-point source pollution owing to technological progress, labor migration, and farmland endowment. The mediation effect of farmland endowment had the highest absolute value (0.0092), and the mediation effects of labor and technological progress were increasing to 0.0040 and 0.0033, respectively. 3) There was significant spatial heterogeneity in the influence of urbanization on fertilizer non-point source pollution. For technological progress, the absolute value of the mediation effect in the major grain-consuming areas was the highest (0.0160), followed by that in the major grain-producing areas (0.0118), whereas the grain-balance areas did not have a significant mediation effect. For labor, there was only a significant mediation effect in the major grain-production areas (0.0538). For farmland endowment, the absolute value of the mediation effect in the major grain-consuming areas was the highest (0.0126), followed by that in the grain-balance areas (0.0095), and the major grain-producing areas had the lowest absolute value (0.0055). The direction of the mediation effect in grain-balance areas was opposite to that in other regions. Therefore, it was important to protect arable land in the major grain-consuming areas and to form a cross-regional collaboration system of “occupation-compensation balance”. In the major grain-producing areas, high-quality labor should be actively guided to return to the agricultural sector. In the grain-balance areas, green agricultural technology and management modes should be introduced.
Mechanism of green production decision-making under the improved theory of planned behavior framework for new agrarian business entities
ZHAO Xiaoying, ZHENG Jun, ZHANG Mingyue, LI Huahua
2021, 29(9): 1636-1648.   doi: 10.13930/j.cnki.cjea.210215
Abstract(14) HTML(6) PDF(5)
Increasing demand for green agricultural products means that the traditional smallholder farm industry cannot meet customers’ requirements, which has encouraged new agrarian business entities to engage in green production. This study used micro survey data from 293 vegetable family farms in Shandong Province to construct a model and empirically test the decision-making mechanism of green production for new agrarian business entities. Based on the theory of planned behavior (TPB), this study added the decision-making process of “environment → cognition” to the TPB to investigate the premise that the “external environment is consistent and stable,” and constructed a decision-making framework mechanism of “external environment → internal cognition → behavioral intention → behavior implementation”. We tested the decision-making framework using structural equation modeling (SEM) and a multi-group analysis method. The conclusions were as follows: 1) from the perspective of the mechanism of action, the external environment (market incentive and government regulation) impacted behavior implementation through the mediating role of internal cognition (behavior attitude and control cognition) and behavioral intention. The relevant hypotheses were significant, and the decision-making model had a good explanatory power for the pre-, during-, and post-green production behavior implementation of vegetable family farms. 2) The influence effects of market incentive, government regulation, behavior attitude, control cognition, and behavior intention were 0.393, 0.177, 0.260, 0.423, and 0.296, respectively. Between the external environmental factors, market incentive was more important than government regulation; while between the internal cognitive factors, control cognition was more important than behavior attitude. Overall, market incentives and control cognition had the greatest effects, followed by behavior and attitude. There were two important decision-making paths: market incentive → control cognition → behavior implementation and market incentive → behavior attitude → behavior implementation. 3) As per factor loading, the load coefficients of industrial cooperation and consumption demand, ecological compensation and technical training, economic value cognition, and behavioral obstacle cognition were the key factors of market incentive, government regulation, behavior attitude, and control cognition, which were important factors in forming the internal cognition of the external environment. Combined with the effects of the potential variables, more attention should be given to the influence of industrial cooperation, consumer demand, behavior obstacle cognition, and economic value cognition on the implementation of green production behavior. 4) The green production decision-making mechanism of family farms with different scales and number of generations of farmers differed. The behavioral intention of small farms did not have a significant impact on behavior implementation, and the behavior attitude of the older generation and small farms did not have a significant effect on behavioral intention. The behavior attitude of large farms did not have a significant effect on behavior implementation, and government regulations did not have a significant effect on behavior and attitude of small farms. Therefore, we should strengthen policy guidance and support for cultivating the market environment, reducing endowment constraints, enhancing economic performance, and rationalizing the decision-making mechanisms to promote green transformation for different types of family farms.
Intercropping enhances agroecosystem services and functioning: Current knowledge and perspectives
LI Long
2016, 24(4): 403-415.  
[Abstract](2931) [PDF 3738KB](2392)
间套作是我国传统农业的精髓, 其存在2 000多年, 必然蕴含重要的科学原理。过去的研究表明其不仅能够大幅度提高作物产量, 而且能够充分利用地上部的光热资源, 充分挖掘和利用地下部水分养分资源, 强化农田生态系统服务功能。近年来, 国内外对其资源高效利用的研究取得了显著的进步, 特别是地下部资源高效利用方面。本文首先综述了相关研究的进展: 间套作作为增加农田生态系统生物多样性的重要措施, 具有重要的生态功能, 如提高作物产量, 增加作物生产力的稳定性, 充分利用地上部光热资源和土壤水分、土壤和肥料中的氮素和磷素以及微量元素等。随后, 对间套作提高资源利用效率的机制进行了分析, 包括水分需求上的时间和空间生态位互补, 豆科/禾本科间作体系中的豆科作物生物固氮和禾本科作物对土壤氮素利用上的互补和促进作用; 磷活化能力强弱搭配的间作体系中, 磷活化能力强的作物对活化能力弱的作物的促进作用; 双子叶和单子叶植物的搭配, 改善双子叶植物的Fe、Zn等微量元素的含量等。最后, 对间套作进一步研究方向和应用提出了一些看法和思路。在研究方面, 包括作物多样性与农业可持续发展, 地下部作物种间信号的传递, 地上地下部多样性的互反馈调节机制, 以及作物生长模型等。在应用方面, 包括豆科作物纳入农业生产体系发展生态集约化农业, 利用间套作发展有机农业, 利用种间相互作用提高磷肥利用率和增加作物可食部分的微量元素含量等。并认为间套作中的机械化、育种等问题的解决将有利于间套作的进一步发展。
Agroecology transition and suitable pathway for eco-agricultural development in China
LUO Shiming
2017, 25(1): 1-7.   doi: 10.13930/j.cnki.cjea.160838
[Abstract](3843) [FullText HTML](7) [PDF 262KB](3345)
"Dual character" of rice-crayfish culture and strategies for its sustainable development
CAO Cougui, JIANG Yang, WANG Jinping, YUAN Pengli, CHEN Songwen
2017, 25(9): 1245-1253.   doi: 10.13930/j.cnki.cjea.170739
[Abstract](641) [FullText HTML](5) [PDF 1905KB](507)
Effect of plant allelochemicals on seed germination and its ecological significance
CHEN Feng, MENG Yongjie, SHUAI Haiwei, LUO Xiaofeng, ZHOU Wenguan, LIU Jianwei, YANG Wenyu, SHU Kai
2017, 25(1): 36-46.   doi: 10.13930/j.cnki.cjea.160632
[Abstract](1531) [FullText HTML](16) [PDF 1004KB](2137)
Responses of soil mineral N contents, enzyme activities and crop yield to different C/N ratio mediated by straw retention and N fertilization
LI Tao, HE Chun’e, GE Xiaoying, OUYANG Zhu
2016, 24(12): 1633-1642.   doi: 10.13930/j.cnki.cjea.160357
[Abstract](1492) [PDF 505KB](1428)
秸秆的质量, 特别是C/N是影响秸秆分解速率和养分释放的重要因素。在秸秆还田条件下, 如何科学合理地施用氮肥是秸秆利用和优化施肥研究的关键问题。本研究以秸秆还田施入碳氮的C/N为切入点, 于2012—2013年通过田间试验(设秸秆不还田不施肥、秸秆还田不施氮、秸秆还田施用无机氮肥调节C/N为10∶1、16∶1和25∶1以及秸秆还田施用有机氮肥调节C/N为25∶1处理), 研究秸秆还田不同氮输入对小麦玉米轮作田土壤无机氮、土壤微生物量氮、酶活性以及作物产量的影响。结果表明: 1)在C/N为25∶1下, 施用有机氮肥和无机氮肥对土壤无机氮含量无显著影响; 在施用无机氮肥的情况下, C/N越低土壤无机氮含量越高。2)秸秆还田施氮提高了土壤微生物量氮含量, 但是各秸秆还田施氮处理之间差异不显著; 秸秆还田不同施氮处理对脲酶活性无显著影响; 秸秆还田施氮提高了FDA水解酶活性, 并随C/N降低呈升高趋势, 施用无机氮肥的效果强于施用有机氮肥的。3)秸秆还田施用无机氮肥显著提高了小麦和玉米地上部生物量, 施用无机氮肥调节C/N为10∶1和16∶1相比于C/N为25∶1提高了小麦和玉米的苗期和成熟期地上部生物量; 施用有机氮肥调节C/N为25∶1相比秸秆还田不施氮对地上部生物量无显著影响。秸秆还田施用无机氮肥提高了作物产量, 施用无机氮肥调节C/N为16∶1产量最高, 而施用有机氮肥调节C/N为25∶1有降低作物产量的趋势。综合以上结果来看, 施用无机氮肥调节C/N为16∶1较为合理。
Nutrient release patterns and decomposition characteristics of different crop straws in drylands and paddy fields
DAI Wencai, GAO Ming, LAN Muling, HUANG Rong, WANG Jinzhu, WANG Zifang, HAN Xiaofei
2017, 25(2): 188-199.   doi: 10.13930/j.cnki.cjea.160748
[Abstract](1470) [FullText HTML](4) [PDF 495KB](1228)
以水稻、小麦、玉米秸秆和油菜、蚕豆青秆为研究对象,采用尼龙网袋法,研究了不同秸秆翻埋入旱地和水田后的腐解特性及养分释放规律,以期为紫色丘陵区农业秸秆循环利用和秸秆还田技术提供理论依据。结果表明:秸秆翻埋还田后,5种供试秸秆腐解速率均表现为前期(0~60 d)快、后期(60~360 d)慢。经过360 d的腐解,旱地秸秆累积腐解率为52.88%~75.80%,表现为油菜 > 水稻 > 玉米 > 小麦 > 蚕豆趋势,且蚕豆青秆累积腐解率显著低于其余秸秆;水田中秸秆累积腐解率为45.01%~62.12%,表现为水稻 > 玉米 > 小麦 > 油菜 > 蚕豆趋势。5种秸秆在旱地和水田中养分释放率均表现为钾 > 磷 > 氮 > 碳,在试验终点,旱地中秸秆碳、氮、磷和钾释放率分别为65.50%~87.37%、54.64%~69.72%、89.65%~98.96%和79.92%~96.63%,且油菜秸秆养分释放率高于其他4种秸秆;水田中秸秆碳、氮、磷、钾释放率变幅分别为49.95%~69.57%、32.89%~77.11%、90.70%~96.80%、77.45%~90.47%。总体表现为秸秆在旱地土壤中的累积腐解率和养分释放率均大于水田,旱地油菜和水稻秸秆较易腐解,水田水稻和玉米秸秆较易腐解释;秸秆中钾素释放速率较高。
Winter wheat LAI estimation using unmanned aerial vehicle RGB-imaging
GAO Lin, YANG Guijun, LI Hongjun, LI Zhenhai, FENG Haikuan, WANG Lei, DONG Jinhui, HE Peng
2016, 24(9): 1254-1264.   doi: 10.13930/j.cnki.cjea.151237
[Abstract](1830) [PDF 4566KB](1212)
叶面积指数(LAI)是评价作物长势的重要农学参数之一, 利用遥感技术准确估测作物叶面积指数(LAI)对精准农业意义重大。目前, 数码相机与无人机系统组成的高性价比遥感监测系统在农业研究中已取得一些成果, 但利用无人机数码影像开展作物LAI估测研究还少有尝试。为论证利用无人机数码影像估测冬小麦LAI的可行性, 本文以获取到的3个关键生育期(孕穗期、开花期和灌浆期)冬小麦无人机数码影像为数据源, 利用数字图像转换原理构建出10种数字图像特征参数, 并系统地分析了3个生育期内两个冬小麦品种在4种氮水平下的LAI与数字图像特征参数之间的关联性。结果表明, 在LAI随生育期发生变化的同时, 10种数字图像特征参数中R/(R+G+B)和本文提出的基于无人机数码影像红、绿、蓝通道DN值以及可见光大气阻抗植被指数(VARI)计算原理构建的数字图像特征参数UAV-based VARIRGB也有规律性变化, 说明冬小麦的施氮差异不仅对LAI有影响, 也对某些数字图像特征参数有一定影响; 在不同条件(品种、氮营养水平以及生育期)下的数字图像特征参数与LAI的相关性分析中, R/(R+G+B)和UAV-based VARIRGB与LAI显著相关。进而, 研究评价了R/(R+G+B)和UAV-based VARIRGB构建的LAI估测模型, 最终确定UAV-based VARIRGB为估测冬小麦LAI的最佳参数指标。结果表明UAV-based VARIRGB指数模型估测的LAI与实测LAI拟合性较好(R2=0.71, RMSE=0.8, P<0.01)。本研究证明将无人机数码影像应用于冬小麦LAI探测是可行的, 这也为高性价比无人机遥感系统的精准农业应用增添了新成果和经验。
Effect of integrated rice-crayfish farming system on soil physico-chemical properties in waterlogged paddy soils
SI Guohan, PENG Chenglin, XU Xiangyu, XU Dabing, YUAN Jiafu, LI Jinhua
2017, 25(1): 61-68.   doi: 10.13930/j.cnki.cjea.160661
[Abstract](1516) [FullText HTML](25) [PDF 337KB](995)
稻虾共作模式是一种以涝渍水田为基础,以种稻为中心,稻草还田养虾为特点的复合生态系统。本文通过10年(2005-2015年)定位试验,以中稻单作模式为对照,研究了稻虾共作模式对0~10 cm、10~20 cm、20~30 cm和30~40 cm土层土壤理化性状以及水稻产量的影响;采用投入产出法,评估了稻虾共作模式的经济效益。结果表明,长期稻虾共作模式显著降低了15~30 cm土层的土壤紧实度,其在15 cm、20 cm、25 cm和30 cm处的土壤紧实度较中稻单作模式分别降低了20.9%、29.9%、24.8%和14.7%。长期稻虾共作模式提高了0~40 cm土层中>0.25 mm水稳性团聚体数量、平均质量直径和几何平均直径,但降低了0~20 cm土层的团聚体分形维数。相对于中稻单作模式,长期稻虾共作模式显著提高了0~40 cm土层有机碳、全钾和碱解氮含量,0~30 cm土层全氮含量,0~10 cm土层全磷和速效磷含量以及20~40 cm土层速效钾含量。稻虾共作模式显著降低了0~10 cm土层还原性物质总量,但提高了20~30 cm土层土壤还原性物质总量。稻虾共作模式的水稻产量较中稻单作模式显著提高,增幅为9.5%,其总产值、利润和产投比较中稻单作模式分别增加了46 818.0元·hm-2、40 188.0元·hm-2和100.0%。可见稻虾共作模式改善了土壤结构,增加了土壤养分,提高了水稻产量以及经济效益,但增加了10 cm以下土层潜育化的风险。
Greenhouse gas exchange and comprehensive global warming potential under different wheat-maize rotation patterns
YAN Cuiping, ZHANG Yuming, HU Chunsheng, DONG Wenxu, WANG Yuying, LI Xiaoxin, QIN Shuping
2016, 24(6): 704-715.  
[Abstract](2269) [PDF 481KB](1446)
研究不同耕作措施下小麦玉米轮作农田N2O、CO2和CH4等温室气体的综合增温潜势, 有助于科学评价农业管理措施在减少温室气体排放和减缓全球变暖方面的作用, 为制定温室气体减排措施提供依据。基于2001年开始的位于华北太行山前平原中国科学院栾城农业生态系统试验站的不同耕作与秸秆还田方式定位试验, 应用静态箱/气相色谱法于2008年10月冬小麦播种时开始, 连续两个作物轮作年动态监测了秸秆整秸覆盖免耕播种(M1)、秸秆粉碎覆盖免耕(M2)、秸秆粉碎还田旋耕(X)、秸秆粉碎还田深翻耕(F)和无秸秆还田深翻耕(CK, 代表传统耕作方式)5种情况下冬小麦夏玉米轮作农田土壤N2O、CO2和CH4排放通量, 并估算其排放总量。试验期间同步记录每项农事活动机械燃油量、灌溉耗电量、施肥量, 依据燃油、耗电和单位肥料量的碳排放系数统一转换为等碳当量, 测定作物产量、地上部生物量, 估算农田碳截存量, 根据每个分支项对温室效应的作用估算了5个处理的综合增温潜势。结果表明, 华北小麦玉米轮作农田土壤是N2O和CO2的排放源, 是CH4的吸收汇, 每年M1、M2、X、F和CK农田土壤N2O排放总量依次为2.06 kg(N2O-N).hm-2、2.28 kg(N2O-N).hm-2、2.54 kg(N2O-N).hm-2、3.87 kg(N2O-N).hm-2和2.29 kg(N2O-N).hm-2, CO2排放总量依次为 6 904 kg(CO2-C).hm-2、7 351 kg(CO2-C).hm-2、8 873 kg(CO2-C).hm-2、9 065 kg(CO2-C).hm-2和7 425 kg(CO2-C).hm-2, CH4吸收量依次为2.50 kg(CH4-C).hm-2、1.77 kg(CH4-C).hm-2、1.33 kg(CH4-C).hm-2、1.38 kg(CH4-C).hm-2和1.57 kg(CH4-C).hm-2。M1和M2处理农田生态系统综合增温潜势(GWP)均为负值, 表明免耕情况下农田生态系统为大气的碳汇, 去除农事活动引起的直接或间接排放的等当量碳, 每年农田生态系统净截留碳947~1 070 kg(C).hm-2; 其他处理农田生态系统的GWP值均为正值, 表明温室气体是由系统向大气排放, CK、F和X每年向大气分别排放等当量碳3 364 kg(C).hm-2、989 kg(C).hm-2和343 kg(C).hm-2。故华北小麦玉米轮作体系中, 秸秆粉碎还田旋耕是最优化的耕作措施, 其温室效应相对较低, 而又能保证较高的经济产量。
Effect of straw strip covering on ridges on soil water content and potato yield under rain-fed semiarid conditions
HAN Fanxiang, CHANG Lei, CHAI Shouxi, YANG Changgang, CHENG Hongbo, YANG Delong, LI Hui, LI Bowen, LI Shoulei, SONG Yali, LAN Xuemei
2016, 24(7): 874-882.  
[Abstract](1458) [PDF 490KB](1002)
水分不足是限制半干旱雨养作物生长的主要因素, 地表覆盖能够改善土壤的微环境, 从而显著提高作物的产量和水分利用效率。为明确西北半干旱雨养区不同保墒措施下旱地马铃薯的土壤水分特征及其对产量的影响, 于2014—2015年设置了玉米秸秆带状覆盖种植(T1)、半膜大垄(T2)、全膜双垄(T3)和露地平作(对照, CK) 4种栽培模式, 研究了玉米秸秆带状覆盖、地膜覆盖种植对马铃薯产量、土壤水分变化及其利用效率的影响。结果表明: 不同覆盖方式能有效改善马铃薯生育期0~200 cm土层土壤水分状况, 地膜覆盖对马铃薯生育前期土壤水分保蓄效果较好, 秸秆带状覆盖对生育中后期土壤水分状况的改善效果明显。与对照(CK)相比, 3种覆盖处理均提高了土壤含水量, 其中T1处理效果最好, 较CK提高2.8%~7.8%, 尤其在伏旱阶段的块茎形成期, 0~200 cm土层土壤含水量高于地膜覆盖处理。与CK相比, T1处理马铃薯产量提高10.5%~34.2%, 水分利用效率(WUE)提高8.9%~29.8%, 达108.9~134.0 kg·hm-2 ·mm-1, 商品薯率提高14.7%~38.8%, 达82.3%~92.2%。马铃薯产量与生育期耗水量(r=0.836**)呈显著正相关。T1的产量和商品薯率均显著高于T2和T3(P<0.05)。可见, 玉米秸秆带状覆盖具有显著的纳雨保墒作用, 促进马铃薯的生长发育, 增产效果显著。其推广应用可有效提高该区降水资源的利用效率, 实现马铃薯稳产高产, 可作为西北雨养农业区旱地马铃薯生产的高效栽培新模式。
Application of spatial viewshed analysis in classifying scenic forests along the Badaling Great Wall
ZHAO Guang-Liang
2013, 21(9): 1157-1165.   doi: 10.3724/SP.J.1011.2013.01157
[Abstract](2980) [PDF 14735KB](1)
The scenic forests along the Badaling Great Wall (BGW) is 2 227.8 hm2, with a forested area of 1 314.2 hm2. The configuration and management of the scenic forests along BGW are important elements of the scenery. In this study, spatial viewshed analysis on ERDAS virtual GIS platform was used to configure the scenic forests along BGW. First, the scenic forests along BGW and a "tourist" were put in a virtual three-dimension space. The "tourist" viewed the scenic forests from 35 observation spots of different coordinates. The view ranges of the "tourist" were divided into three levels - close range (0~500 m), moderate range (500~1 000 m) and long distance (1 000~2 000 m). Then the view range and inter-visibility of the "tourist" at the three view range levels at every observation spot were recorded. Based on the view results, the scenic forests was divided into vision blunt, perceptive and sensitive areas. The results of the viewshed analysis were overlaid with vegetation and BGW forest origin data to generate a zone map. Then the landscape type of every patch of the scenic forest in the map was determined in terms of view perception. The results showed that the vision blunt area, perceptive area and sensitive area of the scenic forests along BGW were respectively 824.44 hm2, 880.4 hm2 and 3 247.77 hm2, respectively, in the farthest view rang (2 000 m). Through overlay analysis, scenic forests along BGW were divided into 119 landscape patches. For management convenience, the patches were classified into 10 forest groups. The groups included protection shrubbery in vision sensitive area, protection forest in vision sensitive area, protection shrubbery in view perceptive area, protection forest in view perception area, protection forest in vision blunt area, sightseeing forest in vision sensitive area, sightseeing forest in vision perception area, sightseeing forest in vision blunt area, recreation forest in vision sensitive area and recreation forest in vision perception area. The study provided the scientific basis for scientific management of scenic forests along BGW.
Response of suitable distribution of citrus in Sichuan Province to climate change
LIN Zhengyu, CHEN Qiang, DENG Liangji, LI Xiao, HE Peng, XIONG Ying
2019, 27(6): 845-859.   doi: 10.13930/j.cnki.cjea.180983
[Abstract](2533) [FullText HTML](47) [PDF 13495KB](47)
Citrus is one of the main fruit products of Sichuan Province, China. Due to favorable market expectations and the low occurrence of citrus diseases in Sichuan basin, there is a trend of blind expansion of citrus cultivation. However, climate change has had a significant impact on the spatial distribution of crops, and has caused the instability and vulnerability of citrus production in Sichuan. In order to optimize the citrus production space, this study established a model of the relationship between the distribution of areas suitable for growing citrus and environmental variables based on the maximum entropy model (MaxEnt), used the ROC curve to determine the model's accuracy, and used the jackknife method to screen out the dominant environmental variables. The distribution of citrus-suitable areas in Sichuan Province in 1980 and 2010 were compared using ArcGIS, revealing the changes in citrus-suitable areas over nearly 30 years of climate change. The results showed that the dominant environmental variables determining citrus suitability in Sichuan were climatic variables characterized by light, heat, and water. During these 30 years, the trend of climate warming and drying in Sichuan Province changed the structure and function of the regional ecosystem, and caused temporal and spatial variations in citrus-suitable areas. There were two broad changes in the spatial pattern of citrus-suitable areas from 1980 to 2010. First, the highly suitable areas tended to migrate to the north. The boundary of moderately suitable areas located between Chengdu Plain area and northeastern Sichuan Province moved to the southeast. Second, the suitability grade changed in a stepwise fashion. The change in the grades in marginally and moderately suitable areas was obvious. In 2010, the total highly suitable area was about 42 200 km2, moderately suitable areas covered about 41 900 km2, and the least suitable areas covered 44 000 km2; most of the province was not suitable. Using this data of the highly suitable areas, government departments can create policies to increase the quantity of citrus in the south Sichuan region and the southern Shengdu Plain. This study objectively assessed the changes in suitability for planting citrus in Sichuan Province under climate change, and provided a scientific basis for the optimization of citrus space. Application of the maximum entropy model is valuable for accurate simulation and prediction of crop distribution and can be important in guiding crop climatic suitability zoning. However, appropriate environmental variables, spatial scale, and species sampling locations should be selected for different regions and crops to reduce systematic cumulative error and improve the precision of crop climatic suitability zoning.

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:Institute of Genetics and Developmental Biology, Chinese Academy of SciencesChinese Society of Ecological Economics

ISSN 2096-6237
CN 13-1432/S
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