中国生态农业学报(中英文)

Effect of long-term addition of organic substances on soil nitrogen and amino sugars in particle-size fractions in the North China Plain

LI Jundi, ZHANG Yuming, ZHAO Baohua, HU Chunsheng, HE Hongbo, DONG Wenxu, WANG Yuying, LI Xiaoxin

2019, 27(4): 507-518. doi: 10.13930/j.cnki.cjea.190084

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Abstract:
The North China Plain (NCP) is one of the main grain production bases in China. In pursuance of high yield, excessive application of chemical fertilizers has been becoming increasingly common and problematic, especially in terms of soil quality degradation. A long-term experiment on soil organic nutrient recycling was conducted at Luancheng Agroecosystem Experimental Station, Chinese Academy of Sciences in this study. The aim was to evaluate the effects of different exogenous organic materials application on the distribution of nitrogen and amino sugar in different soil particle-size fractions and to provide the basis for explaining the soil physical and biological protection mechanisms of nitrogen under different management practices. The experiment had six treatments in triplicates-no chemical fertilizer without organic materials (CK), single application of pig manure (M), application of chemical fertilizers (NPK), combined application of chemical fertilizers and pig manure (MNPK), combined application of chemical fertilizers and straw (SNPK) and single application of straws (SCK). Three particle-size fractions (sand:2 000-53 μm, silt:53-2 μm and clay: < 2 μm) were separated through ultrasonic dispersion and centrifugal separation. Total nitrogen and amino sugars (glucosamine, muramic acid and amino galactose) were analyzed within these fractions and in the bulk soil. Based on the stability and heterogeneity of three soil amino sugars, we used amino sugar as index for fungal/bacterial residue accumulation and transformation to explain the role of fungi/bacteria in nutrient conversion. The results indicated that the addition of organic materials (straw and pig manure) significantly increased contents of total nitrogen and amino sugars in bulk soil and different particle-size fractions with order of clay fraction > sand fraction > silt fraction. The effect of adding exogenous organic substances on soil nitrogen content was most obvious in sand fraction. Soil nitrogen in MNPK treatment was enriched mainly in sand fraction, and nitrogen in SNPK was most enriched in clay fraction. Straw addition increased soil content of glucosamine from fungal residue, pig manure application increased content of muramic acid from bacteria residue, indicating obvious effect of exogenous organic substances on community structure of soil microorganisms. The ratios of glucosamine/muramic of soil particle-size fractions showed that bacteria dominated under pig manure application, and fungi dominated under CK or straw addition in nutrient decomposition and transformation, which was most obvious in sand fraction. In summary, partial replacement of chemical fertilizers with organic manure not only reduced chemical fertilizer use, but also increased soil nutrient content, improved microbial community structure and soil quality.

Prediction of atmospheric ammonia concentration in farmlands using BP neural network

QU Ying, WANG Mian, DONG Wenxu, WANG Yuheng

2019, 27(4): 519-528. doi: 10.13930/j.cnki.cjea.181057

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Abstract:
The emission of ammonia from agricultural system is the main source of atmospheric ammonia and nitrogen fertilizer application is the main sources of ammonia emission in agriculture. The prediction of the changes in atmospheric ammonia concentration and the determination of the factors driving atmospheric ammonia emission will be benefit to the basis for scientific and rational farmland management and for control of environmental pollution. In this paper, BP neural network was used to analyze the concentration of ammonia in farmlands and its relationship with various meteorological factors. The aim was to better understand the changes in ammonia concentration in farmlands and provide new idea and method of study of ammonia in farmlands. First, farmland ammonia measured with Laser Analyzer and meteorological monitoring data from May to October 2015 were used to establish a model for the prediction of farmland ammonia with meteorological factors (air pressure, air temperature, relative humidity, precipitation, wind speed and sunshine hours) as input variables. Secondly, principal component analysis was used to screen meteorological factors with the strongest effect on the ammonia concentration in farmlands, including air temperature, relative humidity, precipitation and wind speed. Then four main factors and six original factors were used as input variables to predict ammonia concentration in farmlands in the region. The results showed that the actual ammonia concentration in farmlands was 0.148 5 mg·m^-3, the predicted value based on four factors was 0.159 4 mg·m^-3 (with predicted error of 7.35%) and the predicted value based on six factors was 0.173 2 mg·m^-3 (with predicted error of 16.65%). The range of the relative error of four prediction factors was 1.4%-27.0% and that of six factors was 1.1%-45.0%. The predicted concentration of ammonia in farmlands varied greatly in the first five days, decreased gradually and apparently flattened out with time, which was basically consistent with the measured value. Eventually, four factors were used as input variables in building the prediction model. The predicted values of farmland ammonia concentration used four factors were more consistent with measured values than that used six factors. It was noted that the established neural network model after removing redundant factors by principal component analysis method was more effective, and the prediction results were better than those before screening. The model established had better applicability for selecting key factors, and the prediction accuracy was higher. The model constructed in this paper for predicting ammonia concentration in farmlands provided more accurate method and newer idea than before on the analysis of farmland ammonia concentration and the related research.

Soil fungal ITS diversity in cucumber-celery intercropping

QIN Lijin, YU Tiantian, WANG Jiaming, GAO Yinbiao, WANG Shouzheng, LI Zheng, YUN Xingfu

2019, 27(4): 529-536. doi: 10.13930/j.cnki.cjea.180484

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Abstract:
Cucumber wilt is a soil-borne disease that retards cucumber production. Intercropping can be used to reduce the prevalence of plant soil-borne diseases, and celery is widely used in intercropping because of its allelopathic property. This study was carried out to explore the effect of cucumber and celery intercropping on cucumber fusarium wilt and soil fungal diversity. Soils from celery monoculture, cucumber monoculture, and cucumber and celery intercropping were analyzed for fungal ITS diversity. The amount of OUT and the Alpha diversity of soil fungi were reduced with the intercropping. Observed species index, Shannon index, Chao1 index, and Simpson index showed reducing for the intercropping though change was not significant. Five fungal phyla were identified, among which Ascomycota, Zygomycota, and Basidiomycota were the primary ones, accounting for up to 95.50% of the total phyla with the intercropping. Cucumber and celery intercropping and cucumber monoculture appeared to be in the same cluster of phyla, clearly distinct from celery monoculture. There were 329 fungal genera that were identified, and half of their abundance was accounted for by 12 genera, specifically 50.72%, 50.47%, and 47.17% for cucumber and celery intercropping, cucumber monoculture, and celery monoculture, respectively. The genus cluster distribution was consistent with the phylum distribution. Cucumber and celery intercropping altered the structure and composition of the soil fungal community, specifically enriching fungal diversity. The information provided an insight into the use of biological means to control soil-borne diseases encountered in cucumber production.

The effect of continuous cropping of selenium melon on soil fungal community structure

FENG Cui'e, YUE Sijun, JIAN Ani, CHEN Liping, GUO Yang, ZHENG Rui, SU Jianyu

2019, 27(4): 537-544. doi: 10.13930/j.cnki.cjea.180746

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Abstract:
Selenium-melon is an important cash crop in Ningxia, but its yield and quality decrease when continuously cropped. The decrease may be related to soil fungal community changes that take place during continuous cropping, which was determined in this study. Soil samples from continuous cropping of selenium-melon were analyzed using Illumina Miseq high-throughput sequencing. The analysis showed that, after an initial increase, the diversity and density of the fungal community in the soil of continuous cropping decreased. Eight fungal phyla, 25 classes, and 244 genera were identified in the soil samples. Ascomycota and Zygomycota were the predominant phyla, accounting for > 90% of the fungi. The abundance decreased 32.51% for Ascomycota, but increased 29.89% for Zygomycota, after 30 years of continuous cropping. The most predominant genera were Mortierella, Metarhiziun, Pseudallescheria, Fusarium, and Penicillium, and the abundance changes included a 45.81% increase for Pseudallescheria after 5 years, a 26.74% increase for Fusarium after 10 years, a 26.83% decrease for Metarhiziun after 15 years, a 29.68% increase for Penicillium after 20 years, a 18.30% decrease for Metarhiziun after 25 years, and a 29.89% increase for Mortierella after 30 years of continuous cropping. Soil physical and chemical properties were not related to years of continuous cropping, but affected the fungal community structure. Soil total phosphorus, alkaline nitrogen, and available phosphorus were the most influential factors for fungal genus changes. A significant positive correlation was observed between the abundance of Metarhizium and soil total potassium, between the abundance of Pseudomycetes and soil total phosphorus and available potassium, and between the abundance of Penicillium and soil pH, whereas a significant negative correlation was observed between the abundance of Fusarium and soil total phosphorus and alkali-hydrolyzed nitrogen. Diminished production of selenium-melon in continuous cropping was related to soil fungal community changes rather than soil physicochemical properties, demonstrating that selenium-melon soil-borne diseases might be controlled through biological means.

Effect of arbuscular mycorrhizal fungi on metabolic characteristics of microbial community in Solanum nigrum rhizosphere soil with lead stress

HAN Juan, ZHANG Xiangqian, ZHAO Jinli

2019, 27(4): 545-553. doi: 10.13930/j.cnki.cjea.181036

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Abstract:
Pot experiments were conducted to explore the effect of arbuscular mycorrhiza (AM) fungi on the characteristics and differences in rhizosphere soils of Solanum nigrum under different levels of lead stress[0 mg·kg^-1 (CK), 200 mg·kg^-1, 400 mg·kg^-1, 800 mg·kg^-1). To this end, S. nigrum was inoculated with Funneliformis mosseae and Claroideoglomus etunicatum, and the resulting rhizosphere soils collected after 10 weeks of growth under 16 h/8 h, 28℃/20℃ with 12 000 Lux light intensity in a greenhouse. The characteristics and differences in carbon metabolic profiles of microbes were evaluated using the Biolog-ECO micro-plate method. The results showed that:1) the average metabolic activity of microorganisms, described by average well color development (AWCD), decreased-increased-decreased with increasing lead stress. Inoculation with AM fungi improved AWCD significantly under lead stresses, except for 400 mg·kg^-1 Pb⁴⁺. 2) The ability of soil microbes to utilize the four types of carbon substrates (carbohydrate and derivatives, fatty acid and lipids, amino acids, and metabolites) was higher under 400 mg·kg^-1 Pb⁴⁺ than under low (200 mg·kg^-1) and high (800 mg·kg^-1) stresses of Pb⁴⁺. Inoculation with AM fungi significantly improved the ability of soil microbes to utilize amino acid substrates under high lead concentration. 3) Lead stress reduced McIntosh evenness index of rhizosphere soil microbial community, but had no significant impact on richness index, Shannon-Wiener diversity index and Simpson index. Inoculation with AM fungi increased microbial diversity index under lead treatment, and had significant effects on Species richness index, Shannon-Wiener diversity index and Simpson dominance index at medium stress. 4) Under the same Pb⁴⁺ stress, inoculation of AM fungi enhanced metabolic capacity of soil microorganisms for the four major carbon sources, but only had significant effect on amino acids. Principal component analysis showed that metabolites were the most abundant in PC1 and PC2, with respective values of 6 and 4. Sugar was the most abundant in PC3. 5) Under combined effects of lead stress and AM fungi, microbial carbon source utilization was mainly regulated by lead concentration, both had significant interaction effects on microbial carbon source utilization. In conclusion, inoculation with AM fungi increased microbial diversity index of rhizosphere soils of S. nigrum under lead stress, and enhanced utilization of carbon source substrate by rhizosphere soil microbes. This study provided theoretical basis for the application of AM fungi which could strengthen the use of phytoremediation technology in soil remediation for heavy metal pollution.

Assessment of risk and yield loss of rice in Sichuan Province due to heat stress

CHEN Chao, PANG Yanmei, LIU Jia

2019, 27(4): 554-562. doi: 10.13930/j.cnki.cjea.180745

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Abstract:
Under global climate change, agricultural meteorological disasters have been increasing. Heat stress has been one of the most important agrometeorological disasters in Sichuan Province, the affected area, frequency and intensity of heat stress have significantly changed. Therefore, research on the impact of heat stress on rice is critical for sustainable agricultural development and safe production in Sichuan Province. In this study, the following data were used to evaluate the risk of cultivation and yield loss of rice in Sichuan Province due to heat stress:1) daily climate variables (average temperature, maximum temperature and relative humidity) from 84 meteorological stations in Sichuan Province for the period 1981-2015; 2) developmental stages (from heading to flowering, and from grain-filling to harvest) of rice in 84 agro-meteorological observation stations in Sichuan Province for the period 1981-2015; 3) rice yields for the 84 stations in Sichuan Province during the period 1981-2015. The hazard index of heat stress at different rice developmental stages were calculated based on the Chinese National Standard, GB/T 21985-2008 Temperature Index of High Temperature Harm for Main Crops. The meteorological yield of rice was separated from actual yield. And then the risk evaluation model for rice in Sichuan Province due to heat stress was constructed by using rice hazard index for the critical development stages and the whole growth period, and rice yield loss due to heat stress was evaluated. The results showed the average hazard index of heat stress in the period 1981-2015 was highest (6.0) for grain-filling to harvest growth stage, medium (5.0) for the whole growth period and lowest (4.0) for heading to flowering growth stage in Sichuan Province. For the heading-flowering stage, most of the northeast basin and parts of the southern basin were under high or sub-high-risk of heat stress. Dazhou, Guang'an and Luzhou were under high-risk. The western basin, southern basin and southwest Sichuan were under low-risk. For the filling to harvest stage, most of the northeast basin and the southern basin were under high or sub-high-risk of heat stress. Luzhou, part of Nanchong and Yibin were high-risk areas. Most of the western basin, northern basin and southwest Sichuan were low-risk areas. For the whole growth period, most of the northeast basin and southern basin were under high or sub-high-risk. Luzhou, Nanchong and Dazhou were high-risk areas. Most of the western basin, northern basin and southwest Sichuan were low-risk areas. The statistical model for rice yield loss due to heat stress was simple and practicable. Using Yanjiang, Yingshan, Longchang, Yanting and Dazhu as the case study, the differences in historical statistical yields and simulated yields of rice for the years of heat stress were analyzed. The relative error between the statistical yield and the simulated yield of rice affected by heat stress was less than 1.5%. The verification results showed that the model was synthetically reflective of the impact of heat stress on rice yield and that it highly accurately evaluated rice yield loss. The assessment showed that the range of yield loss of rice in typical areas of Sichuan due to heat stress was 5.6%-10.2%.

Improvement effect of agronomic traits in the second backcrossing generation of dryland and irrigated wheat varieties

MAN Qiang, ZHAO Hui, XU Ping, WANG Yafei, LI Shijing, SUN Jutao, LIN Yongling, ZHANG Zhengbin

2019, 27(4): 563-571. doi: 10.13930/j.cnki.cjea.180168

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The winter wheat growing season in the Huang-Huai-Hai area of China is often exposed to drought stress posing a serious threat to the safety of food production. The molecular design breeding by using backcross selection and molecular marker-assisted selection to improve breeding of drought resistant and high water use efficiency varieties become a new direction of future wheat breeding. A total of 200 BC₂ (the second backcrossing generation) plants were obtained from the hybridization between dryland variety 'Chang 6878' as donor parent and irrigated variety 'Jimai 22' as recurrent parent. Ten agronomic traits, including plant height, spike length, internode length under spike, tiller number, spikelet number, grains per spike, biomass per plant, grain weight per plant, 1000-grain weight, economic index, were investigated to analyze the hybridization and backcross effect by the analysis of correlation, cluster and principal component. The results showed that the plant height, spike length, internode length under spike and tiller number of BC₂ plants were biased in favor of the recurrent parent 'Jimai22', while the spike number, grain number per spike, biomass per plant, grain weight per plant, 1000-grain weight, economic index showed super-parents effect. The correlation analysis showed that grain weight per plant was extremely significantly correlated with plant height, spike length, tiller number, spikelet number, grains per spike, biomass per plant, 1000-grain weight. And grain weight per plant was significantly and positively correlated with economic index. The cluster analysis showed that BC₂ population was divided into 4 groups at the Euclidean distance 40. The Class Ⅱ including 'Jimai 22' accounted for 30.5% of the total BC₂ generations, while 'Chang 6878' was divided into Class Ⅳ separately. Class Ⅰ (58% of the total number of BC₂) and Class Ⅱ were merged into a new group at the Euclidean distance 45, therefore 88.5% of BC₂ individuals and 'Jimai 22' were classified into the same cluster. The principal component analysis obtained five principal components, which contributed over 85.51% of variance, and ten BC₂ strains with high comprehensive score were screened as the key choice in the future. These results implied positively direction of genetic improvement in the BC₂ generation, which provided theoretical basis and technical support for the water use efficiency and drought-resistance breeding by wheat backcross.

Modeling root biomass of maize in Northeast China

LYU Guohong, XIE Yanbing, WEN Rihong, WANG Xiaoying, JIA Qingyu

2019, 27(4): 572-580. doi: 10.13930/j.cnki.cjea.180115

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It is of great significance to explore root biomass and establish a universal root biomass model for the monitoring and evaluation of the ecosystem biomass. In order to get the real-time information of a root system, the biomass and ecological indexes of maize root system were collected using soil sampling method and root scanning systems at the agricultural meteorological experiment station in Jinzhou City, Liaoning Province in September 2016. The vertical distribution characteristics of root biomass of maize were analyzed and simulation equations were established based on the relationships between root biomass and root ecological indexes. The results showed that the maize root biomass decreased with increase of soil depth. The root biomass of maize mainly concentrated at the soil depth from 0 cm to 30 cm, which accounted for 94.44% of the total root biomass. The simulation accuracy of exponential and power functions of root biomass with root diameter as independent variable established by ordinary least square method was low, and R² was 0.10 and 0.12, respectively. The biomass model constructed by adding root length as an independent variable significantly improved the simulation accuracy, with R² reaching above 0.91. There was heteroscedasticity issue in the models of root biomass established by the ordinary least square method inducing less stable and inaccurate prediction results. This issue could be eliminated by using logarithmic transformation. The biomass model of maize root system with root length and root dimeter together as variables (D²H) had a better simulation effect and a good prediction accuracy, with the coefficient of determination (R²) as 0.90 and the evaluation indexes MAE, SEE and MPE as 4.38 g, 18.68 g and 16.09%, respectively. The correlation coefficient between simulated and measured values was 0.92 (P < 0.01), indicating that this model could be used to simulate the biomass of maize root system in Northeast China. The study results indicated that the difficulty in observing root biomass in real time could be resolved by using root biomass model combined with the minirhizotron method.

Estimation of changes in soil organic carbon in farmlands in Fuzhou City using Landsat vegetation data and 1:50 000 soil database

LI Ya, ZHANG Liming, CHEN Hanyue, YUAN Yuqi, XING Shihe

2019, 27(4): 581-590. doi: 10.13930/j.cnki.cjea.180753

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Carbon pools in farmlands are critical drivers of change in global carbon stock and a small change in these pools could have a huge influence on CO₂ concentration in the atmosphere, causing global greenhouse condition. Though medium and small scale soil databases have often been used in estimating soil organic carbon (SOC) in farmlands, remote sensing image and large-scale soil database have rarely been used. In this study, we combined remote sensing and carbon cycle model to estimate SOC in farmland of Fuzhou City (in subtropical China) using Landsat TM and Landsat 8 OLI remote sensing images plus 1:50 000 high-resolution soil database. In the study area, SOC in farmlands was calculated for 1987 and 2016. The purpose of the study was to determine whether the study area was source or sink of SOC and the dynamics of SOC pool in the region. The results showed that:1) there was a strong linear relationship between soil basal respiration and soil organic carbon density (SOCD) in farmlands in Fuzhou City. The determinant coefficient R² was 0.637 for 1987 and 0.752 for 2016. 2) For the study period, SOCD in farmlands increased from eastern coastal area to western inland area. In general, SOCD and soil organic carbon storage (SOCS) increased by 0.20 kg·m^-2 in the eastern coastal area and 2.946×10⁵ kg·m^-2 in western inland area, indicating that farmlands in Fuzhou City served as a weak "carbon sink" in the past 30 years. 3) In terms of soil type, yellow earth, red earth and paddy soil contributed the largest to "carbon sink" across the soil groups, with respective SOCD increases of 0.70 kg·m^-2, 0.40 kg·m^-2 and 0.19 kg·m^-2. Fluvo-aquic soil, latosolic red soil, aeolian soil, coastal solonchak and purplish soil were the biggest contributors to "carbon source" across the soil group. Comparison of SOCS of different soil types in 1987 with those in 2016 showed that SOCS was highest in paddy soil, accounting for over 90% of the total carbon storage in Fuzhou City. 4) In terms of administrative region, Cangshan District, Changle District, Mawei District and Lianjiang County were "carbon source" areas. Then Minhou County, Minqing County, Fuqing City, Jin'an District, Yongtai County and Luoyuan County were "carbon sink" areas. The lowest SOCS was in Cangshan District in Fuzhou City, with less than 0.5% of total SOCS. Fuqing City always ranked the highest in Fuzhou City, accounting for over 20.0% of the total SOCS. In general, the spatial dynamics of SOCD in farmlands in Fuzhou City during the 30-year period were significant. Additionally, there were differences in different soil types and administrative regions in terms of SOCD. In future, it was beneficial to conduct farmland management based on soil type in different farmlands and SOC in the administrative regions.

Evaluation of rice planting suitability using GIS and geochemical land quality data-A case study of Qingyang County, Anhui Province

HAN Huijie, XIA Xueqi, WU Haidong, TANG Ming, JIANG Mingliang

2019, 27(4): 591-600. doi: 10.13930/j.cnki.cjea.180699

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In order to accelerate the construction of high-standard basic farmlands in Qingyang County, Anhui Province and to conduct more accurate evaluation of rice planting suitability, an Analytic Hierarchy Process (AHP) was used to evaluate the suitability of rice planting with site conditions, soil physicochemical properties, soil quality and land management as the criterion layer. We then used the driving factors as the index layer to successively devise a three-level hierarchical model for the evaluation. Thus, the evaluation system comprising 12 indicators (including soil nutrient, soil environment, soil texture, soil organic matter, drainage capability, irrigation capacity, and etc.) were constructed based on geochemical land quality data of the prime farmland in the study area and on the demand for local rice production. With the polygons of the Second Land Survey as evaluation units, the field slope was obtained from digital elevation model (DEM) data, and combined with spatial analysis technology in GIS to simulate spatial interpolation of geochemical data. The Delphi method was used to determine index membership and build judgment matrix to calculate the weight of each index in order to obtain the comprehensive rice planting suitability index (RSI). The results showed that the "highly suitable" land area was 36.89 km², accounting for 19.80% of the total area, which was mainly distributed in the central and southern regions of the study area. The areas of "suitable" and "barely suitable" lands were respectively 61.95 km² (33.25%) and 60.89 km² (32.68%) and were sporadically distributed. The area of "unsuitable" land was 26.60 km² (14.27%) and was also mainly distributed in the central and northern regions of the study area. The measured cadmium content of rice seeds and RSI were significantly negatively correlated. The cadmium content of rice grains gradually decreased with the increasing of RSI. The low heavy metal content implied improvement of rice quality and reduction in potential damage to the ecological environment through food chain. The results proved the correctness and applicability of the evaluation method from the perspective of ecological security. We explored rice production issues reflected by geochemical data of land quality. The established evaluation method of agricultural planting suitability improved the past evaluation methods, which was subjective and non-suitable for application due to many descriptive indicators and uncertain indicator grading.

Spatial distribution of cultivated land quality at different scales in Chongyi County

SUN Congkang, XU Junli, YU Dun, ZHOU Wei, WANG Jianping, LIANG Zhenbao

2019, 27(4): 601-612. doi: 10.13930/j.cnki.cjea.180891

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While the quality of cultivated lands is the primary basis for judging the productivity of land, the characteristics of the spatial distribution of land quality are critical for farmland research. Multi-scale study of cultivated land quality and spatial structural characteristics are inevitable in strengthening rational allocation of land resources for the protection of cultivated lands. The enrichment of scientific connotation of cultivated land quality should objectively reflect spatial distribution differences in natural quality, utilization quality and economic quality at different scales. Based on the First Law of Geography and specific characteristics of Chongyi County, typical hilly and mountain areas were selected and evaluated for cultivated land quality in a spatial autocorrelation model supported by platforms such as Geoda and GS+. The work discussed the spatial interactions and distributions of natural quality, utilization quality and economic quality of cultivated lands at county, township and village scales. The results show that:1) the natural quality of cultivated lands in Chongyi County was during grade 9-12 and the utilization quality during grade 6-9. There was a gradually increasing "northwest to southeast" trend with an economic quality of grade 7-10. There was a degree of spatial aggregation effect which was strongest when spatial distance was 4 500 m. The Moran's I value of cultivated land quality showed that natural quality (0.445) > economic quality (0.406) > utilization quality (0.281). The natural quality of cultivated land had the strongest positive spatial correlation with weakest degree of variation, while the utilization quality was weakest in spatial correlation and strongest in spatial variability. 2) The quality of cultivated lands showed different scale effects for different quality indexes. For the difference in spatial aggregation between township and county scales, the natural quality was largest, followed by economic quality and then utilization quality. Larger spatial scales weakened spatial aggregation, and spatial aggregation effect was most significant at village scale. 3) The spatial agglomeration type HH of cultivated land quality was mainly distributed in the southwest of county, LL distributed in Jinkeng Village and Zhukeng Village. The HH type of utilization quality was mainly distributed in the flat Longgous and Qianchang Townships, and LL type in deep mountain area where the elevation was higher and the cultivated land most dispersed. The HH type of economic concentrated in Guantian Town, Longqi Township and Shangbao Township where the terrain was relatively flat and the road access degree high. The LL type was distributed in a strip shape in relatively occluded area. The research results revealed that cultivated land quality had different spatial differentiation characteristics at different spatial scales and large spatial scale weakened the aggregation difference of cultivated land quality. The research had practical significance for monitoring and protection of cultivated lands at different spatial scales and more accurate management of arable land quality.

Evolution of green total factor productivity and regional disparity in China's husbandry

XU Biaowen, SHEN Zhiyang, LIN Guohua

2019, 27(4): 613-622. doi: 10.13930/j.cnki.cjea.180912

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Green total factor productivity (TFP) is a key indicator for measuring the transformation mode of economic development. The promotion of green TFP has been particularly important for achieving high-quality development of animal husbandry. Existing literatures on green TFP have ignored inter-regional heterogeneity. The productivity index has been usually measured based on distance functions of evaluated unit (province) own leading to results not inter-comparable among units. consequently failure in providing accurate policy advice for decision makers. This paper proposed a novel approach of allocating the contributions of economic gain and environmental improvement to green TFP growth of every evaluated unit. Based on the concept, the main contribution was based on a robust aggregate directional distance function and aggregate Luenberger productivity indicators. We set a unified direction for all over China to measure green TFP evolution of animal husbandry in 31 provinces for the period 2001-2016. The results showed that:1) generally, the average annual growth rate of green TFP in China's animal husbandry was 5.01%; of which the contribution rate of economic efficiency was 88.83% and that of technological progress as high as 78.65%. 2) There were regional imbalances in the development of animal husbandry industry across provinces, with eastern and central regions having faster growth than western areas. 3) There was potential of improvement in green TFP growth of animal husbandry in China with bigger room for improvement of environment efficiency than economic efficiency. Different directions of the improvement of green TFP growth of animal husbandry existed among the eastern, central and western regions of China. For the eastern regions, economy growth and carbon emission was in weak decoupling with small improvement room of TFP growth. For the central regions, both economic and environment efficiencies had great improvement room. And the western region had certain potential in economic efficiency enhancement and carbon emission reduction. Thus in order to realize high-quality development of animal husbandry, there was need to accelerate the transformation from relying on increasing the input of factors to environmental improvement for increasing green TFP of animal husbandry, and to strengthen the innovation of green science and technology. Also to realize balanced development of animal husbandry, it was necessary to break the police obstacles between urban and rural areas, and among regions, and increase per capita animal husbandry output value.

Spatial-temporal changes of ecosystem service values in Xiangxi region based on terrain

CHEN Yizhu, XIAO Yi, SUN Siqi, GUO Luo

2019, 27(4): 623-631. doi: 10.13930/j.cnki.cjea.180751

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To understand the change of land use and ecosystem service value (ESV) on different terrain gradients, this study used remote sensing data, field data and statistic data of Xiangxi region in 1990, 1995, 2000, 2005, 2010 and 2015 to analyze the change of each land use types along the gradients of elevation, slope, aspect and terrain index, which were classified into five levels by quantile method, respectively. The study also evaluated the ESV with XIE Gaodi's method to explore the spatio-temporal change of ESV in Xiangxi region. And R Studio and Pearson correlations were used to analyze correlation between areas changes of different land use types and change of ESV with terrain gradients. The results showed that:1) areas of different land use types were significantly different on different terrain gradients. The human-activity-affected cropland and construction land mainly distributed on low gradients of elevation, slope and terrain index, while the natural systems, such as forestland and grassland, were mainly on high gradients of the three terrain factors. The south and east slopes were with larger areas of each land use type. Forestland occupied about 70% area on every terrain gradient, and the construction land area significantly increased on every terrain gradient over 25 years. 2) ESV decreased first and then increased with increasing elevation. From 1990 to 2015, ESV increased at lower elevation gradient, however, change was slighter at higher elevation, and it even decreased on the highest elevation gradient. ESV increased with slope growth. Over 25 years, ESV increased most on the lowest slope gradient. In a similar way, ESV evenly increased with increasing terrain index gradient. ESV was the lowest in southeast slope, highest in northwest slope, and increased most in east and northwest slopes from 1990 to 2015. 3) Correlations between change of land use types areas and ESV with gradients of elevation, slope, aspect, terrain index were different. On elevation gradient, grassland area change significantly positively correlated with ESV change. On slope gradient, forestland and grassland areas changes both had extremely positive correlation with ESV change. On aspect gradient, cropland and unused land areas changes had extremely negative correlation with ESV change, while forestland had a significant positive correlation. On terrain index gradient, areas changes of forestland and grassland were significantly correlated with change of ESV. In summary, the changes of land use and ESV were obviously different regarding topography. Forestland and grassland were two important land use types for improvement of ESV in mountain area of Xiangxi region.

Factors affecting cognition and behavior of clean production in large-scale pig farms-A case of 509 large-scale pig farmers in Shandong Province

YU Chao, ZHANG Yuanyuan, SUN Shimin

2019, 27(4): 632-643. doi: 10.13930/j.cnki.cjea.180811

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Abstract:
Pig breeding is a key source of environmental pollution. The clean production of large-scale pig farm is critical for preventing pollution by pig breeding. Based on the theory of planned behavior, using data derived from 509 questionnaires of a survey in 17 cities, Shandong Province, structural equation model was used to empirically analyze the driving factors and their action mechanisms of cognition and behavior of clean production in large-scale pig farms. The results showed that the attitude of large-scale pig farmers to clean production and characteristics of pig farm households had significantly positive impact on cleaner production perception. The former was mainly driven by understanding of clean production and familiarity with pig breeding pollution, and latter included age, years of schooling and slaughter fattened hogs number of farmers. External regulations consisting of government support and requirements of cooperative organizations had positive but no significant impact on cleaner production perception. The cognition of clean production in large-scale pig farms had significant positive impact on source prevention, process control and terminal governance behaviors. Clean production attitude, endowment characteristics and external regulation had indirect impact on cleaner production behavior of farmers. The action mechanism was as follows:clean production behavior of large-scale pig farmers was subject to the degree of cognition, which was the result of interaction of behavioral subject attitudes, external regulations and subject endowment characteristics. This was attributed to continuous communication between the external environment (government, operating organizations, upstream and downstream enterprises, etc.) and the behavioral agent. It was noted that clean production behavior mechanism of large-scale pig farmers was not a simple linear effect between individual factors, but the result of interaction among the participants of the whole industrial chain and the environment. Therefore, based on the driving factors and mechanism of cognition and behavior, improving positive attitude of large-scale pig farmers towards cleaner production, strengthening external regulations and reinforcing subject endowment had positive influence on degree of cognition. Acting on formation and improvement of behavior and ultimately reducing pollution of pig breeding led to achievable economic and environmental benefits.

The influence of intergenerational transmission of farming practices on organic fertilizer utilization willingness of rice producers

ZENG Yangmei, ZHANG Junbiao, HE Ke

2019, 27(4): 644-653. doi: 10.13930/j.cnki.cjea.180723

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Abstract:
In view of family based farming in China, the influence of intergenerational transmission of farm operation on rice producers' attitude toward the use of organic fertilizer was studied. A survey was conducted in Hubei Province, and data obtained from 563 households were analyzed using Binary Logistic Model. The following observations were obtained:1) 52.93% of the rice producers surveyed were willing to use organic fertilizer. 2) The likelihood for a rice producer to use organic fertilizer decreased in a slope of 0.101 with the level of interactive transmission up one grade, but increased with the level of demonstrative transmission up one grade in a slope of 0.206; the influence of demonstrative transmission was enhanced by weakened interactive transmission. 3) Young and middle-aged producers were influenced by both demonstrative and interactive transmissions independently or jointly, while elderly producers were influenced mainly when the transmissions were presented interactively. 4) Producers' attitude was also affected by land fertility, education, income, perception of risks, and policy satisfaction. These observations suggested that a producer's adoption of environmentally friendly practices in agriculture such as using organic fertilizer could be fostered by magnifying the positive effect of demonstrative transmission of parents' behaviors, education, low risk technology introduction, and governmental support, thus promoting the application of green agricultural technologies, such as organic fertilizer.

System dynamic research on interactive development of rural e-commerce and revitalization

GUO Na, LI Huawei

2019, 27(4): 654-664. doi: 10.13930/j.cnki.cjea.180933

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Abstract:
The implementation of rural revitalization strategy has provided sufficient policy guarantee for rural infrastructure construction, rural economic structure innovation and rural technical personnel training; in turn greatly improving the external environment and internal requirements of rural e-commerce development. Also the development of rural e-commerce has promoted the implementation of rural revitalization strategy in terms of market expansion, industrial upgrading and financing. In order to achieve high-efficiency interaction between the two strategies, we constructed a system dynamics model of interactive development between rural e-commerce and rural revitalization to show causal relationship and dynamic feedback mechanism among the four subsystems of number of rural e-commerce operators, agricultural special product market, rural e-commerce professional talents scale and capital scale. Based on statistical data of rural economic development in China for 2010-2016, we simulated the interaction between rural e-commerce and rural revitalization. Stability and validity tests of the system dynamics model showed that the model truly reflected actual system structure and function of rural e-commerce and rural revitalization in rural economic growth. On this basis, the policy of the interactive development between rural e-commerce and rural revitalization was further simulated by adjusting the values of four policy variables of rural e-commerce fixed asset investment parameter, rural e-commerce education investment parameter, agricultural financial subsidy factor and rural resident consumption subsidy factor. The simulation results showed that the main factor influencing interactive development between rural e-commerce and rural revitalization was the intensity of agricultural financial subsidies. Also relevant supporting policies had different effects on the process of interactive development between rural e-commerce and rural revitalization, with obvious stage characteristics. Therefore, gradually increasing the intensity of agricultural financial subsidies and building comprehensive policy support systems were necessary to realize interactive development between rural e-commerce and rural revitalization. Also according to current conditions of rural e-commerce development and rural revitalization strategy implementation, there was need to focus on promoting relevant policies to promote interactive development between rural e-commerce and rural revitalization in a phased and targeted manner.

2019 Vol. 27, No. 4