中国生态农业学报(中英文)

Innovation in agroecological and organic farming systems

Niggli Urs, Wang-Müller Qiyan, Willer Helga, Fuchs Jacques

2021, 29(3): 423-430. doi: 10.13930/j.cnki.cjea.200469

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In light of major ongoing environmental damage and the destruction of natural resources, developing a truly sustainable mode of agricultural production is of great importance. Among different ways to reduce trade-offs between ecological sustainability and productivity, we present the approaches taken by agro-ecological and organic farmers. Both fall within the narrative of ecological intensification. According to finding of many previous scientific meta-analyses, both have a great potential to reduce environmental pollution. However, these very positive effects unfortunately result in lower yields. These could be compensated for by changing people's eating habits (e.g. less food waste, less meat consumption from concentrate-fed livestock). However, since global developments and trends are moving in exactly the opposite direction, this paper examines the possibilities of improving the yields of low-input farming systems through scientific research and the outlook for finding new productive solutions. Here we outline the significant potential in the redesign and differentiation of farms and fields including landscapes, in digitalization, the promotion of low-input breeding programs, high quality recycling of organic matter, and non-chemical crop protection.

Can organic agriculture feed China? Implications from the nitrogen supply

MENG Fanqiao, ZHANG Ke, WANG Fang, WANG Kun, WU Wenliang, WANG Kaiyong, HU Zhengjiang, ZHANG Haixia

2021, 29(3): 431-439. doi: 10.13930/j.cnki.cjea.200584

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In recent years, organic agriculture has been rapidly developed in China and throughout the world. However, the position and role of organic agriculture in overall agriculture and the corresponding development strategy of organic agriculture are still debated. From the perspective of nitrogen (N) supply, this study attempted to evaluate the effects of not using synthetic fertilizer N on foodstuff production and consumption and to provide technical support for N management in China. The study selected the whole agroecosystem in China and quantified the symbiotic N fixation, the impact of agricultural product on N supply and grain production, and the population fed under different levels of foodstuff consumption. The annual N fixation capacity of leguminous crops in China was 15.41×10⁶ t·a^-1 if organic agriculture was adopted for all agricultural land. If no chemical N fertilizer was applied, the total agricultural product output in 1979 and 2018 was 381.96×10⁶ and 420.72×10⁶ t, respectively. These agricultural products (excluding vegetables and fruits) could feed a population of 0.81×10⁹-1.24×10⁹ and 0.50×10⁹-0.77×10⁹, respectively. Thus, if all agricultural lands were completely operated with organic agriculture principles and under the current acreage of agricultural land and science and technology levels, it would be difficult to feed the entire population of China. With consideration of the imported agricultural products, the actual per capita grain consumption (converted to standard grain, excluding vegetables and fruits) was 689.35 kg·a^-1 in 2018. Reductions in food waste, adjusting the food consumption structure, and increasing grain imports are key measures for resolving the food security issues in China. The importation of soybeans and other agricultural products has played an important role in reducing fertilizer usage in recent years in China. Chemical N fertilizer has made a great contribution to grain production in China, but there is still room for improvement in N fertilizer efficiency. Organic and ecological agriculture emphasizes the principles of holistic, coordination, circulation, and regeneration, which is the theoretical basis and technical guarantee to promote sustainable agriculture that will play a dominating role in agricultural development. The integration of cropping with livestock production should be disseminated and implemented throughout China to reduce resource waste and environmental pollution. At the policy and legislative levels, ecological compensation, and crop integration with livestock production may increase N utilization efficiency and achieve multiple goals of agricultural development, including food security, food safety, and ecological soundness.

Agglomeration and spatial dependence of organic agriculture in China

LU Yu, XIANG Ping'an, YU Liang

2021, 29(3): 440-452. doi: 10.13930/j.cnki.cjea.200650

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Although organic agriculture is an important way to realize the green development of agriculture, the supported policies from the public sectors are necessary. It is important to accurately grasp the spatial distribution of organic agriculture in China as well as test the agglomeration and spatial dependence of organic agriculture in China for the public sectors to design policies. Assuming that agglomeration and spatial dependence do matter in organic agriculture distribution, this paper explored the localization and spatial clusters of organic agriculture in China on a provincial level from 2013 to 2018. Firstly, we use Jenks natural break class to analyze the spatial distribution of organic agriculture in China. Then, we use EG index, location entropy and industrial agglomeration index to analyze the agglomeration of organic agricultural. Finally, Moran's I index is used to check the spatial dependence, the hot/cold spot analysis based on the local Getis-Ord G_i^* statistics and standard deviation ellipse method are used to discuss the local spatial agglomeration pattern and evolution trend furtherly. The results show that: 1) the organic agriculture has not been expanded evenly across China instead concentrating in certain regions, based on the proportion of organic production area and organic product certification demonstration area, Northeast and western regions have advantages; while based on the organic product certification and organic certified enterprises, the eastern region has advantages. 2) the EG index of organic agriculture in China is greater than 0.02 and has exceeded 0.05 after 2016, which indicates the high degree of agglomeration in China's organic agriculture. The industrial agglomeration index and location entropy of Qinghai, Inner Mongolia, Ningxia, Xinjiang and Hainan are all greater than 1, which indicates that these provinces have obvious agglomeration advantages in organic agriculture. 3) The global Moran's I is greater than zero and increases year by year, which indicates that there exists the positive spatial dependence among the provinces adjacent to each other. The hot spots of organic agriculture mainly expanded from northeast to west, the cold spots and sub-cold spots spread in the middle and eastern region. The distribution and center of gravity of organic agriculture showed a trend from northeast to west. There are various reasons for the remarkable agglomeration of organic agriculture in China. In addition to the location factors such as the regional favorable climate and policy, agglomeration effect and spatial dependence are also considered important in determining spatial distribution of organic agriculture. Potential policy implication should include a concentration of development measures for organic farming in certain regions. It may be better to support the development of organic agriculture in underdeveloped areas with good ecological environment. Regions with agglomeration advantages in organic agriculture, the government can enhance the concentration degree of organic agriculture through further supporting policies, and form a virtuous circle of agglomeration and diffusion. Places adjacent to the agglomeration regions benefit from the spillover effects to achieve the promotion of organic agriculture. Targeted policies from the public sectors may be more conducive to the development of organic agriculture than inclusive policies.

Effects of different fertilizer treatments on nutrient absorption and distribution in organic Astragalus

GAO Youhui, JIANG Chunyan, HU Yuegao, WANG Xiaofen

2021, 29(3): 453-464. doi: 10.13930/j.cnki.cjea.200631

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Milkvetch (Astragalus membranaceus) is a staple herbal medicine in China. Few studies have investigated the nutrient requirements and fertilization management of organic milkvetch, and there are only a few reports on the proportioning and application of organic, mineral, and microbial fertilizers, which conform with organic cultivation. In this study, Mongolian milkvetch (Astragalus membranaceus var. mongholicus) was subjected to five treatments: no fertilizer (CK), chemical fertilizer (C), organic fertilizer (O), organic fertilizer + mineral fertilizer (OM), and organic fertilizer + mineral fertilizer + microbial fertilizer (OMD). The effects of different fertilizer treatments on the absorption, accumulation, and allocation of nine mineral nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, copper, and zinc) were systematically studied in the organs of organic Mongolian milkvetch. The results showed that the contents of nine mineral elements in various organs of Mongolian milkvetch varied with different fertilizer treatments. The accumulation of various elements in the roots of Mongolian milkvetch showed a gradually increasing trend, and the elements in the stems and leaves showed a dynamic trend, increasing at first and then decreasing. The application of chemical fertilizer effectively promoted the accumulation of iron, manganese, copper, and zinc in the stems and leaves of Mongolian milkvetch. Organic fertilizer combined with mineral and microbial fertilizers significantly promoted the accumulation of nitrogen, potassium, iron, manganese, copper, and zinc in the roots and promoted the accumulation of phosphorus in the stems and leaves. During the 180-day growth period after transplanting, organic fertilizer combined with mineral and microbial fertilizers performed best in all fertilization treatments. Compared with other treatments, the OMD treatment promoted the distribution of nine nutrients to the stems and leaves and provided more nutrients for growth. In summary, organic fertilizer combined with mineral and microbial fertilizers can effectively promote the accumulation and allocation of mineral nutrients in Mongolian milkvetch. This may represent the physiological basis for high yield and high-quality organic Mongolian milkvetch. However, the physiological mechanisms need further study.

Effects of different organic fertilization patterns on the nitrogen and phosphorus runoff losses in organic agriculture in watershed areas

HAN Xiao, XI Yunguan, TIAN Wei, WANG Chao, HE Liping, LI Lina

2021, 29(3): 465-473. doi: 10.13930/j.cnki.cjea.200242

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Runoff of nitrogen and phosphorus from farmland is an critical source of river and lake pollution. Organic farming in watersheds could be beneficial for the environment and water quality compared to conventional farming. However, overuse of organic fertilizer can also lead to an increased risk of phosphorus loss. The aim of this study was to analyze the effects of different organic fertilizer application patterns on vegetable yield and nitrogen and phosphorus runoff losses. A field experiment was conducted by building runoff pounds in a vegetable plot in the Songhua Dam watershed, a representative plateau lake in Yunnan Province. Chemical fertilization was the control treatment (CF), and the effects of different organic fertilizer application patterns of cow manure (DMC), chicken manure (CMC), and mixed fertilization of cow manure, chicken manure, and soybean cake (HH) were compared at fertilization rates of 100%, 80%, and 60% of the N input of CF. The vegetable production and nitrogen and phosphorus runoff losses were compared. The dynamic change in total nitrogen (TN) runoff concentration showed that the initial phase (0-25 d) after fertilization was an important period to take preventive and control measures for nitrogen runoff caused by chemical fertilizer application. The results showed that the cumulative concentration of TN in the runoff with organic fertilizer application was significantly lower (26.3%-73.9%) than in the CF treatment after 25 days of fertilization. During the growth stage, the reduction in cumulative concentrations of TN in the runoff was 32.8%-67.0% under organic fertilizer application compared with CF. The cumulative concentration of total phosphorus (TP) in the runoff increased by 49.1% and 12.3% with the DMC and CMC treatments, respectively, but decreased by 15.8%-52.5% under the other organic fertilization treatments. Variance analysis indicated that the nitrogen input levels and the organic fertilzer types could significantly affected the concentration of TN, ammonium, nitrate, and TP in the runoff, and they also had significant interactions with the ammonium nitrogen and TP concentrations. Under 100% N input, the impact of fertilization patterns on TN in the runoff was as follows: CF > DMC > HH > CMC. TP in the runoff was as follows: DMC > CMC > HH > CF. Soil nitrate and available phosphorus were CF > DMC ≈ CMC > HH and CMC > DMC > HH > CF, respectively. Under 60% N input, the reduction of TN and TP in the runoff was significantly greater than 80% and 100% N inputs. The content of soil available phosphorus increased under the organic fertilization treatments compared with CF. Compared with CF and the other types of organic fertilizer, HH significantly increased the yield and quality of broccoli (Brassica oleracea), while the yield of DMC and CMC tended to decrease. On the presumption that broccoli yield increased by 16.7%, the 0.6 HH combination could significantly reduce TN, nitrate, ammonium, and TP in the runoff by 66.5% (18.94 mg·L^-1), 67.2% (11.11 mg·L^-1), 66.2% (6.57 mg·L^-1), and 52.5% (0.5 mg·L^-1), respectively, and could be used as the recommended fertilization system to promote organic vegetable production and to reduce nitrogen and phosphorus runoff losses in the Songhua Dam watershed. The results presented here provide reference and technical support for water quality protection through organic agriculture in China.

Effect of organic management on soil quality under different land use types

CAO Chunxia, ZHU Shenghai, YAN Yue, LONG Wuci, LI Chun, XIE Bingyi, LIU Yunhui, DUAN Meichun

2021, 29(3): 474-482. doi: 10.13930/j.cnki.cjea.200932

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The soil quality of farmlands can be improved by organic management, but this conclusion is unclear under different land-use types. A soil quality survey based on an organically managed farm with diversified land use and nearby conventionally managed farmland was conducted by analyzing differences in the soil quality under two different management measures within five land use types (greenhouse vegetable fields, orchards, open-air vegetable fields, farmland boundaries, and paddy ridge). Analysis of variance (ANOVA) and principal component analysis of 20 indicators of soil nutrients contents, heavy metals contents, and soil animal numbers were used to explore the impact of organic management on soil quality under different land use types. The results showed that the pH value of the organic management was significantly higher than that of conventional farmland overall (the average value of five land use types). Meantime, the organic management overallly significantly decreased soil contents of total P, total K, available P, total Cr, total Cu, total Ni, and total Zn; and increased amounts of soil Araneae, Diplopoda, ground beetle and earthworm, compared with the conventional management. But for the specific land use type, pH increased significantly in the open-air vegetable field and farmland boundary under organic management. The organic matter content and total nitrogen contents of the open-air vegetable fields, and the quantities of Araneae, Diplopoda, ground beetles, and earthworms in the soil under organic management were higher. The total Cr, total Ni, and total Zn contents in the greenhouse vegetable fields, total Zn contents in the open-air vegetable fields and farmland boundaries, total Cu contents in orchards and paddy ridges were lower. The numbers of ground beetles and earthworms in the paddy ridge, and Diplopoda in the orchard were higher under organic management. Principal component analysis indicated that there was a significant difference in soil quality under different management practices. The numbers of Araneae, Diplopoda, ground beetles, and earthworms in the soil were higher, and the pH values and contents of P, Cu, Pb, Zn, and Cr were lower under organic management. These results show that the soil quality was better under organic management, but this was not universal for all land use types due to factors such as the specific management practices, the number of artificial inputs, and the length of organic planting time. The extent to which land quality had been improved under different land use types differed, so it is necessary to take targeted soil improvement measures under diverse land use types.

Effects of management measures and soil factors on the diversity of ground spider communities in five agricultural habitat types

LONG Wuci, LI Tianyi, LI Chun, XIE Bingyi, REN Shaopeng, JIN Shuquan, YU Zhenrong, LIU Yunhui, DUAN Meichun

2021, 29(3): 483-491. doi: 10.13930/j.cnki.cjea.200934

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Empirical studies have demonstrated the positive effects of organic management on farmland biodiversity, but the consistency of this effect between different agricultural habitat types has not been explored. Therefore, a comparison study was conducted between two adjacent farmlands, both with multiple habitats but subjected to contrasting management measures (organic vs. conventional). We sampled spiders using pitfall traps and examined differences in their diversity across organically and conventionally managed farmlands for five different habitat types (vegetable greenhouses, orchards, open-air fields, field margins, and paddy ridges). We also examined how the soil factors affect spider diversity. No significant differences were detected in species richness between the organically and conventionally managed farmlands, but spider abundance in the organically managed orchards was 139% higher than in the conventionally managed orchards. Within the same management system, spider abundance and species richness in the field margins of conventionally managed agricultural areas were 104% and 59% higher than in other habitats, respectively. The difference in spider community composition in organically managed farmland was slightly larger than in conventionally managed farmlands. Meanwhile, the difference in spider community composition between different habitat types was greater in organically managed farmlands than in conventionally managed farmlands. The organic matter content, total nitrogen, and total phosphorus in the soil significantly affected the spider community structure, but these factors did not correlate with spider abundance or species richness. There was a significant negative correlation between total copper (Cu) and spider abundance. This study showed that the spider community is affected by many factors. The management intensity of different habitat types and the vegetation structure were more important than management practices and soil factors. Thus, it is important to create different agricultural habitats and develop organic management techniques to sustain beta-diversity at the landscape scale. Maintaining semi-natural habitats (such as field margins with rich vegetation), reducing agrochemical inputs and disturbances on farmlands, and preventing soil heavy metal pollution may help sustain spider diversity in conventionally managed farmlands.

Ground-dwelling spider diversity within organic and conventional croplands in the hilly and plain areas of North China

LIU Ruhua, SUN Renhua, SONG Chengjun, LIU Qingsheng, LIU Yunhui, DUAN Meichun, ZHANG Xuzhu

2021, 29(3): 492-499. doi: 10.13930/j.cnki.cjea.200538

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The growing demand for food has led to increased focus on agricultural development in hilly areas. However, intensive agriculture may be one of the main reasons for biodiversity loss in the landscape. To better understand the effects of production management practices and boundary hedges on ground-dwelling spider biodiversity in different topographic areas, this study was conducted at five different farmlands in a typical agricultural area of North China. In the hilly area, conventional maize fields with and without a plant hedge (CMH/CM) and organic maize fields with or without a plant hedge (OMH/OM) were sampled for spiders. Conventional maize fields without a plant hedge were also sampled in the plain area (PCM). Spiders were sampled using pitfall traps from August to September 2019. The results showed that the Shannon diversity and rarefied species diversity of spiders in the maize fields were significantly higher in the hilly area than in the plain area; and organically managed maize fields had significantly higher spider rarefied species diversity than conventional maize fields. Furthermore, the spider rarefied species diversity was significantly higher in maize fields with hedges than without hedges. The species composition of the spider assemblages significantly differed between the farmlands with organic and conventional management, between the farmlands in the hills and plains, and between the farmlands with and without hedges. Based on these results, we recommend that regional land use planning and zoning management strategies be applied to improve agricultural production development and conserve biodiversity. The hilly region experiences less human disturbance and has greater diversity; thus, it may represent a hotspot for biodiversity conservation in an intensive agriculture region that could be promoted by developing extensive agriculture (such as organic agriculture) and more diverse landscapes with hedgerows. In the plain area, the semi-natural boundary should be reserved, and the agricultural production intensity should be reduced to improve the environment and promote green development.

Interactive effect of elevated CO₂ concentration and drought on photosynthetic and physiological indexes of foxtail millet

LIU Yajing, ZHANG Dongsheng, LI Ping, ZONG Yuzheng, HAO Xingyu

2021, 29(3): 500-508. doi: 10.13930/j.cnki.cjea.200528

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There is a lack of knowledge on the interactive effects of elevated atmospheric carbon dioxide (CO₂) concentrations ([CO₂]) and drought on the photosynthesis and physiological processes underlying foxtail millet drought resistance. An experiment was conducted in an open-top chamber with two CO₂ treatments, ambient [CO₂] (CK, 400 μmol·mol^-1) and elevated [CO₂] (ECO₂, 600 μmol·mol^-1), and two water treatments, normal water (relative water content was 75%-85% soil capacity) and drought (relative water content was 35%-45% soil capacity). We quantified the interactive effects of elevated CO₂ and drought on the gas exchange parameters, fluorescence parameters, and drought-resistant physiological indicators in millet. The results showed that elevated CO₂ could reduce the content of photosynthetic pigment under drought conditions. Elevated [CO₂] aggravated millet stomatal closure at the booting stage, alleviated the negative effects of drought on the net photosynthetic rate at the filling stage, and increased the water utilization efficiency. During the booting stage, elevated [CO₂] resulted in a 66.7% reduction in stomatal conductance under normal water conditions and a 77.7% reduction under drought conditions. During the grouting period, under normal water conditions, elevated [CO₂] led to a 19.0% increase in the grain net photosynthetic rate and a 37.1% increase in water use efficiency; under drought conditions, it led to an 87.7% increase in the grain net photosynthetic rate and a 39.2% increase in water use efficiency, respectively compared with that of ambient [CO₂]. Drought significantly reduced all of the millet fluorescence kinetic parameters, except non-photochemical quenching (NPQ), and elevated [CO₂] alleviated this effect in the grouting period. At the booting stage, ECO₂ and drought showed significant interactive effects on the intrinsic efficiency of photosystem Ⅱ (PSⅡ) (F_v/F_m'), PSⅡ photochemistry (ΦPSⅡ), and the highest photosynthetic electron transport (ETR) and photochemical quenching coefficient (qP). Elevated [CO₂] significantly reduced the content of cellulose and activity of peroxidase (POD) under normal water conditions. POD activity (under ECO₂), and contents of proline, soluble total sugar, starch content (under CK), and the cellulose content (under ECO₂) were significantly increased under drought conditions. We conclude that elevated [CO₂] can enhance the drought resistance of C₄ foxtail millet by improving the photochemical efficiency of photosystem Ⅱ and the activity of antioxidant enzymes.

Effects of CO₂ concentration enrichment on the grain quality of different rice varieties

NIU Xichao, HU Shaowu, YANG Yang, TONG Kaicheng, JING Liquan, ZHU Jianguo, WANG Yulong, YANG Lianxin, WANG Yunxia

2021, 29(3): 509-519. doi: 10.13930/j.cnki.cjea.200558

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Increasing atmospheric carbon dioxide (CO₂) concentration leads to global warming and has a profound effect on the growth and development of crops. As a substrate for plant photosynthesis, high CO₂ concentration can increase rice yields, but the effect on rice quality is still unclear. The genotypic variation in rice quality in response to high CO₂ concentration is less studied than rice yield. In this study, eight rice varieties were grown under ambient and elevated CO₂ concentrations (200 μmol·mol^-1 higher than ambient) in a free-air CO₂ enrichment (FACE) platform. The effects of elevated CO₂ concentrations on rice processing quality, appearance quality, eating quality, and nutritional quality were studied, and grain quality differences among rice varieties in response to elevated CO₂ concentration were also investigated. All of the quality traits varied significantly among the tested varieties. Compared with rice plants grown under ambient CO₂ concentration, plants grown under FACE treatment tended to have decreased brown rice percentage, white rice percentage, and head rice percentage, but had significantly increased yields of brown rice, white rice, and head rice (by 23.7%, 23.5%, and 20.9%, respectively). FACE treatment had little effect on the head rice length, head rice width, and the ratio of head rice length to width, but significantly increased the chalky rice rate and chalkiness degree. Averaged across all rice varieties, the elevated CO₂ concentration increased the chalky rice rate and chalkiness degree by 18.6% and 31.8%, respectively. FACE treatment reduced the amylose concentration and gel consistency by an average of 6.5% and 3.1%, respectively, but the reduction was not significant. The response in the rapid visco analyzer (RVA) profile of rice starch to elevated CO₂ concentration was also studied. FACE treatment increased the mean value of peak viscosity and breakdown by 1.3% and 6.9%, respectively, for all varieties, but decreased the mean value of hot viscosity, cold viscosity, and setback by 2.2%, 5.1%, and 65.6%, respectively. However, only the reduction in setback was statistically significant. The phytic acid concentration of the rice grains significantly increased by 5.3% on average, whereas the protein content significantly decreased by 9.9% under FACE conditions. The response of the rice quality traits to high CO₂ concentration varied in direction and magnitude among different varieties. An interaction between CO₂ treatment and rice variety was found for head rice length, chalky rice rate, chalkiness degree, peak viscosity, hot viscosity, and cold viscosity. The above data suggest that increased atmospheric CO₂ concentration significantly increased grain yield, but tended to diminish the processing quality, appearance quality, and nutritional quality of the rice grains while improving the palatability of cooked rice. The response of rice grain quality to elevated CO₂ concentration varied across rice varieties.

Differentiation in the bacterial community structure of mulberry leaf surfaces in the canopy where mulberry ring rot disease occurs

YIN Shilin, ZHANG Jianhua, LI Xingyue, TANG Tian, WANG Xie

2021, 29(3): 520-530. doi: 10.13930/j.cnki.cjea.200542

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To identify the antagonistic bacteria of Gonatophragmium, this study investigated variations in the diversity, structure, and function of phylloplane microorganisms in the mulberry ring rot disease areas of mulberry canopy. Using high-throughput sequencing technology, we analyzed the relative abundance of bacteria on the upper and lower surfaces of the upper and lower leaves in the canopy. The results showed that 1) the Shannon index in upper canopy was 1.26 times of that in the lower canopy, and the upper surface of leaves was 1.49 times of that in the lower surface. 2) The dominant genera in the lower surface of a leaf in the lower canopy (LB) and the lower surface of a leaf in the upper canopy (UB) were the genus Pantoea, with relative abundances of 38.04% and 25.31%, respectively. In the upper surface of a leaf in the lower canopy (LS), it was Serratia and the upper surface of a leaf in the upper canopy (US) was Stenotrophomonas, with relative abundances of 18.0% and 23.73%, respectively. 3) The transport and metabolism of carbohydrates and amino acids of bacteria in the lower canopy leaves were stronger than those in the upper canopy leaves; however, lipid metabolism and transport were weaker in the lower canopy leaves. The cell wall biogenesis function of bacteria on the upper surface of leaf in upper canopy was stronger than that on the lower surface, whereas the amino acid transport and metabolism functions were weaker on the upper surface. The biosynthesis, transport, and catabolism of secondary metabolites, lipid transport, and the metabolism of bacteria on the upper surface of lower canopy leaves were stronger than those on the lower surface, but cell movement was weaker on the upper surface. The relative abundances of Bacillus, Asticcacaulis, and Phenylobacterium were significantly negatively related to the relative abundance of pathogens (P < 0.05); the most significant correlation was for Bacillus (-0.87). These results indicate significant differences in the diversity, structure, and function of bacterial communities on the upper and lower surfaces of mulberry leaves in the canopy, which will assist further research on the biological control of mulberry ring rot disease.

Effects of straw returning and fertilization on soil bacterial and fungal community structures and diversities in rice-wheat rotation soil

ZHANG Hanlin, BAI Naling, ZHENG Xianqing, LI Shuangxi, ZHANG Juanqin, ZHANG Haiyun, ZHOU Sheng, SUN Huifeng, LYU Weiguang

2021, 29(3): 531-539. doi: 10.13930/j.cnki.cjea.200502

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Straw returning and slow-release fertilizers are widely used in agriculture to reduce non-point source pollution and improve nitrogen use efficiency. However, there are few studies on the effect of straw return combined with slow-release fertilizers on the soil microbial community. This study determined how straw returning combined with fertilization affected the bacterial and fungal communities in rice-wheat rotation soil and the underlying mechanisms. Based on a seven-year rice-wheat rotation system monitoring experiment, four treatments were selected: no fertilizer (CK), regular chemical fertilization (RT), straw returning combined with chemical fertilization (RS), and straw returning combined with slow-release fertilizer (SS). The Illumina MiSeq platform was used to evaluate the community structure and diversity of soil bacteria and fungi and to detect the primary environmental factors affecting the microbial community. The results showed that the SS rice and wheat yields in 2016 and 2017 were significantly higher than the RT yields (by 11.6% and 8.2% in rice, and 4.8% and 3.6% in wheat, respectively); there was no difference between SS and RS yields. Compared to RT, straw returning significantly decreased soil pH and increased soil organic carbon (SOC) and ammonium nitrogen (NH₄⁺-N) contents; SS had more NH₄⁺-N than RS. The fungal community diversity was higher with straw returning than with RT, but there was no difference in the bacterial community diversity among fertilization treatments; the bacterial and fungal community diversities were the same between RS and SS. Correlation analysis showed that the bacterial community diversity was negatively correlated with pH and positively correlated with soil total nitrogen content, while the fungal community diversity was positively correlated with SOC. Non-metric multidimensional scaling analysis showed that fertilization had a greater effect on the bacterial community structure (55.61%), and straw returning had a greater effect on the fungal community structure (26.94%). Proteobacteria, Chloroflexi, and Acidobacteria (in successive order) were the dominant phyla across all treatments, accounting for 66.07%–71.76% of the total bacterial sequence data. Ascomycota, Basidiomycota, and Zygomycota (in successive order) were the dominant phyla across all treatments, accounting for 88.05%–89.04% of the total fungal sequence data. Compared with RT, the treatments with straw returning significantly increased the relative abundance of Actinobacteria, Chloroflexi, and Firmicutes in the bacterial community, and significantly increased the relative abundance of Ascomycota and decreased the relative abundance of Basidiomycota and Zygomycota in the fungal community. Ecological function analysis of these bacterial and fungal communities showed that straw returning may enhance soil carbon and nitrogen cycling and inhibit pathogens. Compared with RS, SS only increased the relative abundance of Ascomycota in the fungal community; there were no other differences between the relative abundances of bacteria and fungi in RS and SS at the phylum level. Straw returning with slow-release fertilizers can help maintain or improve soil nutrient availability, crop yield, and the diversity of bacterial and fungal communities and can promote soil carbon and nitrogen cycling.

Photosynthetic characteristics of alfalfa seedlings under salt stress based on FvCB model

WANG Wenjing, MA Dongmei, CAI Jinjun, HUANG Ting, MA Qiaoli, ZHAO Lijuan, ZHANG Ying

2021, 29(3): 540-548. doi: 10.13930/j.cnki.cjea.200501

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Understanding the photosynthetic physiological characteristics of alfalfa seedlings under salt stress is important for improving alfalfa growth, restoring the ecological environment, and promoting the development of the foraging industry in China. Alfalfa variety 'Adrenalin' seedlings were treated with different concentrations of NaCl (0 mmol·L^-1, CK; 40 mmol·L^-1, T1; 80 mmol·L^-1, T2; 120 mmol·L^-1, T3; and 160 mmol·L^-1, T4), the light response curves were measured with Li-6400XT, and the effects of NaCl stress on photosynthetic characteristics were analyzed by using FvCB model. The results showed that the leaf net photosynthetic rate (P_n) decreased significantly with increasing NaCl concentration by 1.44% (T1), 7.21% (T2), 7.90% (T3), and 3.85% (T4), respectively, compared with that of CK. The P_n in all treatments showed a rapid upward trend as photosynthetic effective radiation increased, and the P_n growth rate in the normal treatment (CK) was significantly higher than that in the other treatments. Compared with those in the CK, the T1 and T2 treatments increased the alfalfa seedling leaf maximum carboxylation rate (V_cmax; by 3.59% in T1, and 13.88% in T2) and maximum electron transfer rate (J_max; by 11.24% in T1, and 17.47% in T2), but the T3 and T4 treatments reduced V_cmax and J_max. Leaf conductance (g_m) and dark respiration rate (R_d) decreased with increasing NaCl concentration. Compared with those in the CK, the T1 and T2 treatments did not affect g_m, but significantly reduced R_d. The T3 and T4 treatments significantly reduced g_m and R_d compared with CK, T1, and T2 treatments. The FvCB model fitting results of alfalfa P_n under different stress treatments verified that the FvCB sub-model accurately estimated plant leaf photosynthesis, and the results showed that introducing g_m into the model had a high simulation accuracy and low average absolute error. The critical salt tolerance value for alfalfa seedlings was 80–120 mmol·L^-1. As the NaCl concentration increased, the photosynthetic limiting factors changed from mesophyll factors to damaged photosynthetic organs. These results may help formulate effective control measures in Northwest China saline land to improve plant salt tolerance.

The combined effects of cadmium and acetochlor on an earthworm-soil-maize system

LIU Chang'e, QIN Yuanru, MENG Xianghuai, DONG Hongjuan, WANG Peng, YUE Minhui, XIAO Yanlan, WANG Yuanfeng, DUAN Changqun

2021, 29(3): 549-558. doi: 10.13930/j.cnki.cjea.200490

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Abstract:
Heavy metal and pesticide pollution is a major environmental problem, and the combined effects on earthworm-soil-plant systems have not been thoroughly explored. This study investigated the individual and combined effects of cadmium (Cd) and acetochlor on earthworm physiological responses, soil physical and chemical properties, and maize growth and morphological characteristics. The results showed that superoxide dismutase (SOD) activity in earthworms decreased and then increased, whereas the opposite trend was observed with malondialdehyde (MDA) content. The earthworm distribution across soil layers increased in the compound pollution treatment, and the percentage of earthworms in the total soil layer increased by 1.34 times (on day 2) and 1.14 times (on day 50) compared with that in the control group. The soil organic matter and available phosphorus contents were unaffected by treatment time or contamination method, but alkali-hydrolyzable nitrogen content decreased and then increased with Cd + acetochlor pollution. On day 50, the maize root numbers in all treatment groups were significantly lower than those in the control group; the inhibition rates were 23.21% (30 mg·kg^-1 Cd), 42.86% (200 mg·kg^-1 acetochlor), and 50.00% (30 mg·kg^-1 Cd + 200 mg·kg^-1 acetochlor). The maize biomasses and plant heights were largest in the 30 mg·kg^-1 Cd group, followed by the 200 mg·kg^-1 acetochlor group, and were smallest in the 30 mg·kg^-1 Cd + 200 mg·kg^-1 acetochlor group. Correlation analysis showed that the interaction between Cd and acetochlor did not affect earthworm MDA content, soil nutrients, or the maize growth index, but antagonistically affected earthworm SOD activity. This study concluded that combined Cd and acetochlor pollution promoted earthworm distribution in the topsoil and inhibited maize growth by altering the soil's physical and chemical properties.

Determining suitable vegetables for planting after spring wheat harvest in the Ningxia Yellow River Irrigation Area

LIU Genhong, XUE Yinxin, ZHANG Qian, ZHOU Jiarui, MAI Xiaofeng, MU Zhimei

2021, 29(3): 559-571. doi: 10.13930/j.cnki.cjea.200298

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Abstract:
Multiple cropping is important for improving land use and ensuring regional food security. Climate change in the Ningxia Yellow River Irrigation Area in recent years favors a multiple-cropping system. Thus, a hierarchical analysis (AHP) with three secondary indicators and twelve three-level indicators was used to determine the vegetable crops that could be planted after spring wheat harvest based on the climate. By doing so, a double-cropping system could be implemented in the Ningxia Yellow River Irrigation Area. In the irrigation area over the past ten years, the annual accumulated temperature ≥ 10 ℃ was 3407.9 ℃, the annual precipitation was 206.4 mm, and the annual evaporation was 1619.3 mm. These climatic conditions are sufficient for leaf and root vegetables cropping after spring wheat harvest. Compared with the theoretical production potential, the actual yield had room for improvement; the conditions were insufficient for fruit vegetable crops after spring wheat harvest. Among 17 vegetable species (varieties) planted after spring wheat, four had higher use efficiency (turnip, mantanghong, baby cabbage, and cucumber), four improved soil fertility (carrot, turnip, celery, and tomato), and four had higher economic benefits [baby cabbage, turnip, mantanghong, and pepper (Jiaolong 7)]. AHP evaluation showed that eight vegetables were suitable for planting after spring wheat harvest based on their comprehensive benefits: baby cabbage, turnip (white turnip), turnip (mantanghong), pepper (Jiaolong 7), pepper (Yangdashuai), endive, celery, and squash (33.0%); they had 143.0%, 121.5%, 77.7%, 46.3%, 43.0%, 35.5%, 33.1% and 33.0% higher comprehensive benefits than kohlrabi. These eight vegetables can be widely cultivated across the area.

Emergy-based benefit analysis of integrated rice-frog farming

ZHONG Ying, SHA Zhimin, GU Maiyun, WENG Danlong, DU Jiping, CAO Linkui

2021, 29(3): 572-580. doi: 10.13930/j.cnki.cjea.200540

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Abstract:
Integrated rice-frog farming (IRFF) is an ecological farming method that can improve production efficiency and promote sustainable development in agriculture. However, few studies have analyzed the benefits of IRFF. This study performed an emergy analysis to evaluate the IRFF system energy input and output in the Qingpu District, Shanghai, China, from 2015 to 2019 and calculated the self-sufficiency, emergy investment ratio, emergy yield ratio, the environmental loading ratio, and the sustainable development index. The results showed that irrigation water, rainfall chemical energy, compound fertilizer, organic fertilizer, and infrastructure were the primary IRFF system energy inputs; rice, straw, frogs, and policy income were the primary energy outputs. The average emergy self-sufficiency and investment ratios from 2015 to 2019 were 0.18 and 4.86, respectively, with no significant changes over the five years. The average emergy yield ratio was 3.65, which generally increased annually. The average environmental loading ratio was 0.46, trending downwards, and the average sustainable development index was 8.52, trending upwards. Compared with similar farming systems, the IRFF system emergy indices performed better because of the differences in study areas and management modes. In the IRFF system, the natural resource input was less, and the purchasing emergy input and output efficiency were higher than in other systems. These results indicated that the IRFF system had a low dependence on natural resources and placed minimal pressure on the environmental system. The IRFF system had great potential for sustainable development and ecological production, but the results showed that the IRFF system was weak in self-sustainment and fluctuated greatly under the influence of economy and society. The energy value investment and net energy value output rates were also low, and the use of resources was insufficient, but there was development potential. Therefore, to further develop the IRFF system in the Qingpu District, more input emergy should be invested, and diversified commodities should be developed to improve the total output efficiency.

Low carbon performance measurement and dynamic effects: A case study of the planting industry in Shandong Province

YANG Binjian, SUN Hongyu

2021, 29(3): 581-589. doi: 10.13930/j.cnki.cjea.200279

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Abstract:
Increased greenhouse effects have seriously affected the survival and development of human society. Data from the Intergovernmental Panel on Climate Change (IPCC) indicates that agricultural greenhouse gases account for 13.5% of global anthropogenic emissions. This study investigated the planting industry in Shandong Province, China, which accounts for the highest proportion of agricultural output, to provide policy recommendations that should help the planting industry in the province follow a low-carbon development path. This study measured carbon emission, carbon sinks, carbon emission intensity, and the marginal cost of carbon emission reduction; used the DEA Malmquist model to measure the low-carbon performance level; and investigated the dynamic effects of low-carbon driving and constraint on the low-carbon performance of the planting industry in Shandong Province. The results showed that from 2000 to 2018, the carbon emission and carbon sink of planting industry in Shandong Province increased 0.26% and 1.71% averagely every year, while carbon emission intensity and marginal cost of carbon emission reduction decreased 3.12% and 2.10%, respectively. The low-carbon performance index increased slowly with an annual increasing rate of 3.00%, which mainly was driven by the efficiency of technology change. The low-carbon constraint goals and low-carbon drivers were the direct reasons of low-carbon performance change of the planting industry. The carbon emission intensity and low-carbon constraint goals had negative and passive effects on the low-carbon performance of plant industry, respectively. The low-carbon constraint goals played a more important role in the low-carbon performance of plant industry of Shandong Province. The findings of this study suggest that low-carbon development can be achieved by formulating low-carbon laws and regulations and improving the effectiveness of financial support.

Kiwifruit farmers' behavior and its' influencing factors of coping with meteorological disasters: A case study of Shaanxi freezing disaster in 2018

CHENG Shujun, YAN Yan, JIANG Zhide

2021, 29(3): 590-599. doi: 10.13930/j.cnki.cjea.200505

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Abstract:
Meteorological disasters have become the main cause of agricultural harvest failures and fluctuations in agricultural production. To investigate farmers' disaster response behaviors and influencing factors, we used data from 226 microscopic surveys conducted in two counties (Zhouzhi County and Mei County) in the Guanzhong region, Shaanxi Province, China's main kiwifruit production area. We comprehensively analyzed the kiwifruit farmers' disaster response decision-making and behavior, and used Double-hurdle model to analyze the influencing factors. The results showed the following: 1) before and after the disaster, differences were noted in the farmers' behaviors. Before the disaster, farmers painted the main trunks white and used smoke generation in the orchard. After the disaster, farmers cut off frozen branches and sprayed nutrient solution on the trees. 2) The disaster response intensities of the farmers were generally low and country specific differences were noted. Among the 12 kinds of response measures, 190 farmers only used 1-3 kinds, accounting for 85.43% of the farmers undertaking response measures, with an average of 2.1 kinds of measures. Zhouzhi County had a higher proportion of farmers who used response measures, and the behavior intensity was higher than that of farmers in Mei County. 3) Farmers' coping behaviors were influenced by their inherent endowment characteristics and external environmental factors, and the direction of influence was both positive and negative. Variables such as the education level of household head, the number of years the household head had been planting kiwifruit, and the extent of technical training positively affected the farmers' decision-making and behavior intensity. Variables such as the township distance negatively affected the decision-making and intensity of the farmers' coping behaviors. The government should broaden the channels for farmers to obtain information and knowledge and guide them to actively respond to natural disasters. Responding to meteorological disasters is a necessary measure to ensure stable income and sustainable development of the planting industry.

Impact of farmer perceptions on the willingness to participate in the utilization of agricultural waste resources under environmental regulations

ZHAO Huijie, HU Wanbin

2021, 29(3): 600-612. doi: 10.13930/j.cnki.cjea.200898

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Abstract:
To increase farmer willingness to participate in the utilization of agricultural waste resources, improve the rural ecological environment, and comply with farmer expectations of a better living environment, this study developed a multivariate ordered Logistic model based on survey data from 693 farmers in Henan, Shandong, Sichuan, and Heilongjiang provinces. The effects of farmers' value and skill perceptions, cost-benefit perception, and market recycling condition perception on participation willingness were investigated. The results show that: 1) The skill, cost, and distance perceptions of farmers, together with recycling channels and their recycling channel stability perception, have significant effects on their willingness to participate. Skill perception and recycling channel stability perception also have significant positive effects on participation willingness. 2) Environmental regulatory policies are the most important factors underlying farm household agricultural waste resource utilization behavior, and there are differences in the moderating effects of the relationship between farmers' perception and participation willingness. Guiding regulations have significant positive moderating effects on the relationships between farmers' prospects perception and their participation willingness and farmers' skills perception and participation willingness. Restrictive regulations have significant positive moderating effects on the relationships between farmers' perception of recycling importance and their participation willingness, and farmers' recycling channel stability perception and participation willingness. Incentive regulations have significant positive moderating effects on the relationships between farmers' prospects perception and their participation willingness, farmers' skills perception and participation willingness, farmer's income perception and participation willingness, and farmers' recycling channel stability perception and participation willingness. Environmental regulations based on incentives also have a significant negative moderating effect on the relationship between farmer's distance perception with recycling channels, and their participation willingness. Intensive technical training, more subsidies, and improved agricultural waste recycling mechanisms may increase farmer willingness to participate, while the continuous adjustment and optimization of agricultural waste resource utilization and regulatory policies will aid green development of agriculture and rural areas.

2021 Vol. 29, No. 3