中国生态农业学报(中英文)

Development strategies of modern agriculture in South Huanghuai Granary

ZHANG Zhengbin, DUAN Ziyuan, WANG Lifang, ZHAI Lichao, XU Ping, LIU Kun, LI Gui

2017, 25(3): 309-315. doi: 10.13930/j.cnki.cjea.161045

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Abstract:
There are over 4 000 000 hm² medium and low-yield fields in the Huaibei Plain with lime concretion black soil and the easy-dry and easy-water-logged areas formerly flooded by the Yellow River with sand and saline-alkali soil. This region is located at the border lands of 4 provinces, including North Anhui, North Jiangsu, Southwest Shandong and Southeast Henan. This region is located in South Huanghuai (the transition zone from north to south of China), there is preferably warm temperature, moderate rainfall and other nature resources. But as the region is far away from developed economy regions and traffic inconveniences, scientific and technological culture as well social and economic developments have relatively lagged behind. This has resulted in the non-realization of full high agricultural yield potential in the region. Speeding up the transformation of medium and low yields and building new granary in South Huanghuai could increase grain production by 5×10⁹ kg. This will be crucial for the development of modern agriculture and food security in China. Based on global warming, climate change, tend in modern agriculture, green farming and increasing yield quality and efficiency, development strategy of modern agriculture in South Huanghuai was suggested. For crop farming, breeding of new varieties with good resistance to wheat scab and alleviation of wheat scab damage by comprehensive control measures can increase and stabilize grain production and food security. The breeding and amplification of new maize variety with good drought resistance, water-logging tolerance and quick dehydration trait that suit grain harvest by mechanization can increase and stabilize grain production and food security. The expansion of ton-grain-field can ensure food security in South Huanghuai and in China at large. For regional governance, improvement of medium-to-low yields in the Huaibei Plain in lime concretion black soils and in easy-dry and easy-water-logged areas formerly flooded by the Yellow River with sand and saline-alkali soils along with strengthening investment in filed irrigation and drainage systems, building high standard fields assorted well by forest network, road and water channels and wells to ensure stable yield despite drought or excessive rain can increase and stabilize grain production and food security. For modern science and technology, increasing subsidy for agricultural machinery, augmenting the amount of large and medium agricultural machinery, strengthening deep plough and deep scarification and popularizing whole mechanization farming courses will increase and stabilize grain production and food security. For green farming production and quality and efficiency enhancement, pursuing active reduction in the utilization of chemical fertilizers and pesticides, expanding utilization of green bio-fertilizers and other pharmaceuticals that are environment friendly, intensifying efficiency of straw turnover and cycle utilization with bio-resources will increase and stabilize grain production and food security. For sci-tech education, expanding the scale of vocational education, training intellectual peasants and professional services workers, building specialized contingencies for social service will be beneficial for increasing and stabilizing grain production and food security. For regional economic development, growing stronger and larger grain brands in North Anhui; expanding production scale of grains, breeding new modern industry in North Jiangsu; completing synergy-efficient development of agriculture, forestry and animal husbandry in Southwest Shandong; forging flagship of deep-processed Chinese foods in Southeast Henan will increase and stabilize grain production and food security. For agricultural information construction, accelerating popularization of internet, driving quick development of contract farming, export-sales farming and sightseeing agriculture will increase and stabilize grain production and food security. It was suggested that the key sci-tech projects for the "Second Granary" in South Huanghuai should be launched early by the nation. This can promote major grain production areas and economic-sinking areas to become national big granaries, new agricultural economy areas, environmentally graceful areas and sustainable development areas in China.

Temporal and spatial characteristics of nitrogen and phosphorus cycling and environmental losses in the "soil-feed-dairy" production system in Beijing

WEI Sha, BAI Zhaohai, WU Dimei, JIANG Rongfeng, XIA Lijiang, MA Lin

2017, 25(3): 316-327. doi: 10.13930/j.cnki.cjea.160970

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Abstract:
With the increasing of urbanization rate and income, the food demand and food consumption structure has been changed greatly in China, especially for the dairy products. However, the environmental risk of livestock production is also growing quickly under the rapid increase of dairy population and intensification rate. Currently, dairy production is mainly concentrated around the peri-urban area in the big cities on the purpose of access to the market. However, there is little information about the nutrient flow and losses of peri-urban dairy production yet. Increasing understanding of this information is useful for policy makers to regulate the size and location of dairy production, and to achieve a crop-dairy integrated and environmental friendly dairy production system. Here, the performance of nitrogen (N) and phosphorus (P) flow, use efficiency and losses of peri-urban dairy farms in Beijing was assessed, using data of a comprehensive survey conducted on 28 dairy farms during 2012-2013 and calculations with the NUtrient flows in Food chains, Environment and Resources (NUFER) model. The feed formula and feed intake, feeding days and other parameters of the production system were derived from survey data for the year 2012 and 2013, and were derived from NUFER model for the period of 1980-2011. Our results showed that, nitrogen use efficiency (NUE) at the animal level (only lactating dairy cow) increased from 14.9% to 21.2% from 1980 to 2013, and phosphorus use efficiency (PUE) increased from 13.8% to 27.3% during the same period. At the herd level (including calves, breed cows, heifers and dry cows), NUE increased from 14.5% to 18.2%, and PUE increased from 15.8% to 24.9% for the past 33 years. Similarly, both the NUE and PUE increased at the system level (soil-feed-cow chain) during the period of 1980-2013, e.g., NUE increased from 11.3% to 15.8%, and PUE increased from 13.3% to 22.3%. NUE was decreased from 1980 to 1985 at all the three production level, however, steadily increased since 1985. Differed with that of NUE, PUE was steadily increased at all the three production level from 1980. The total nitrogen losses increased from 1 516 t N in 1980 to 16 973 t N in 2013, and the total phosphorus losses increased by 1 649 t P, from 114 t P to 1 763 t P during the same period. The average N or P losses to produce 1 kg N or P in products decreased greatly since 1980. In conclusion, the characteristics of N and P flow thorough the "soil-feed-dairy" production system have been greatly changed in Beijing. The nutrient use efficiency and total environmental losses are increasing. The reasons for these changes are the increasing of animal number, the transformation from the traditional to the intensive farming and the improvement of the environmental management measures. Therefore, it is necessary to improve the sustainable development of urban dairy farming by the adjustment of dairy production from quantity to quality, precision feeding technology, and waste management.

Agricultural groundwater footprint of the major cropping system in the North China Plain: A case study of Wuqiao County, Hebei Province

ZHANG Kai, ZHOU Jie, ZHAO Jie, PEI Kuan, WANG Zhimin, HU Yuegao, ZENG Zhaohai

2017, 25(3): 328-336. doi: 10.13930/j.cnki.cjea.160833

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Abstract:
As a newly developed concept and research method for water footprint studies in recent years, groundwater footprint (GF) could be used to evaluate potential use of renewable groundwater to increase agricultural production or in combination with water footprint and virtual water calculations. The GF method was used to analyze the groundwater resources utilization in agriculture and to assess the environmental impacts in wheat-maize crop rotation system at Wuqiao Experiment Station-a traditional region where wheat-maize crop rotation is practiced in the North China Plain. This study was based on the latest developments in theories and methods of GF in combination with agricultural practices. In addition, GFs of crops were calculated at county scale, and the impact of the different crops on GF analyzed for Wuqiao County in Hebei Province. The results showed that since 1949, GF of winter wheat was higher than that of summer maize, with respective mean values of 89.02 km² and 29.84 km² for Wuqiao County. Also based on the trend of change, GF of winter wheat and summer maize had an increasing trend of fluctuation. In terms of GF stress index (GF per unit area, GF/A_aq) for the crops, winter wheat basically had a moderate stress (0.1 < GF/A_aq < 1) and the stress index for summer maize was less (0.01 < GF/A_aq < 0.1) for most the years, which increased for recent years. Thus if reasonable measures were not taken to control cultivation, GF would increase and have a significant impact on the balance of water circulation in regional environmental system in the coming years. This would put considerable pressure on groundwater resources to meet water needs of crops in Wuqiao County. The research suggested that to reduce groundwater pressure and ensure effective restoration of groundwater resources, the traditional wheat-maize cropping system could be adjusted through the cultivation of peanut and potato, whose GFs were 2.08×10^-7 km²·m^-2 and 1.94×10^-7 km²·m^-2, around 40% and 58% less than that of winter wheat. Thus through the exploration of GF, cropping structure in Wuqiao County could be adjusted or the area of crop rotation between low water-consumption crops and staple grain crops could be increased to enhance the use of water-saving technologies and improvement of water-saving measures. The study showed that GF analysis had the potential for application in agricultural research. It was concluded that in future, basic GF research should be enhanced and GF parameter database construction at various scales and for various crops were required to provide a solid basis for research on sustainable use of groundwater resources and the development of sound government policies.

Response of summer squash pollinator density to habitat loss in Southeast Yunnan, China

XIE Zhenghua, Jonathan Teichroew, AN Jiandong

2017, 25(3): 337-344. doi: 10.13930/j.cnki.cjea.160935

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Abstract:
The response diversity theory claims that functional pollinators differently react to environmental change in a range of spatial and/or temporal scales. Diverse responses of pollinators could contribute to the stabilization and resilience of ecosystem pollination functions by the reorganization of pollinator community. To date, however, little remains known about the responses of Chinese pollinators to environmental changes, especially considering the rich pollinator diversity represented in China. We selected 18 summer squash fields in Guangnan County, Yunnan Province, to study the reaction of bee communities to habitat loss. In our study, habitat loss was represented with two change gradients-one gradient of natural and semi-natural habitats surrounding the squash fields in landscapes (used to investigate landscape effect on pollinators) and one gradient of distance away from natural and semi-natural habitats (used to investigate distance effect on pollinators). While 8 fields were selected to explore the landscape effect, 12 fields were used to explore the distance effect, and of which two fields were simultaneously used for both experiments. Flower visitors were sampled once in the 18 fields on sunny days from June to July 2015. Land use and land cover were derived from Landsat satellite image and were identified as secondary forest, grassland, water, dryland, wetland and building. Secondary forest and grassland were treated as natural and semi-natural habitats, which were beneficial for management and wild bees. Then dryland and wetland were treated as farmland, which were believed to have a diminishing effect on wild bee population. The Pearson correlation coefficient was calculated between pollinator density and percentages of semi-natural habitats and farmlands at a range of nested spatial scales (250 m, 500 m, 750 m, 1 000 m, 1 500 m, 2 000 m and 2 500 m). Responses of honey bee density and bumble bee density along the percentages of natural and semi-natural habitats and farmlands were explored at spatial scales with the highest correlation coefficient. Honey bee and bumble bee density changes along the distance away from natural and semi-natural habitats were also explored. We found that bumble bees and honey bees were the dominate pollinators for squash flowers in the study area. Ants and wasps also visited the squash flowers, but they were not analyzed due to their extremely low densities. Bumble bee density and honey bee density were associated with natural and semi-natural habitats and farmlands at different spatial scales. The percentage of natural and semi-natural habitats was significantly negatively correlated to that of farmlands at spatial scales ranging from 500 m to 2 500 m. Bumble bee density increased along the gradient of natural and semi-natural habitats in landscapes, but honey bee density was not influenced by surrounding natural and semi-natural habitats. While bumble bee density declined as surrounding farmlands increased in landscapes, honey bee density was not influenced by farmlands. Moreover, bumble bee density declined along increasing distance away from natural and semi-natural habitats, but honey bee density was not influenced by the distance to natural and semi-natural habitats. The different responses of honey bees and bumble bees to habitat loss could be related to pollination services of squash. Our findings indicated the need for a special attention by farmers and researchers to understanding and managing crops that are reliant on wild pollinators.

Comparative analysis of three fitting methods of rice trend yield

ZHAO Dongni, WANG Yanhua, REN Chuanyou, MA Xida, XU Yidan, CHEN Wei

2017, 25(3): 345-355. doi: 10.13930/j.cnki.cjea.160933

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Abstract:
It is a prerequisite to have accurate meteorological data for correct assessment of the effects of meteorological factors on grain yield. As such, it is important to explore rational methods to fit trend yields of crops to guide future crop production efforts. In this study, 62 years of historical data on rice yield from 17 sites in 9 regions in Liaoning Province were used to rationalize the separation of the trend yield of rice in relation to meteorological factors. The separated trend yields with three fitting methods-HP filter method, exponential smoothing method and logistic method, were compared and discussed. The rationality of the above three methods were evaluated based on the following preconditions:1) the agricultural productivity and technological development in similar regions was consistent, 2) the yield series change reflected promoting effects of state favorable policies on crop yield, and 3) uniformity of the regions with similar heat condition caused same changes in crop yield. The results showed that:1) the trend yield series fitted by the three methods were consistent with the average trend yield series of Liaoning Province, suggesting that the three methods properly reflected the regional consistency of development. Results analysis indicated good consistencies of trend yields of Shenyang, Tieling, Anshan, Liaoyang, Dandong, Jinzhou with that of Liaoning Province, and coefficients of correlation for the regions was as high as 0.91.2) The trend yield series fitted by HP filter method truly reflected the actual trend yield affected by the changes in the levels of national productivity and national policy. This suggested that the goodness of fit for the HP filter method with actual trend yield was the best, followed by the exponential smoothing method. The extraction of the trend yield also basically reflected actual social development, whereas the goodness of fit for the logistic method had the worst performance. 3) Average regional meteorological yield series obtained with different methods had similar inter-annual and inter-decadal variation characteristics, with no significant difference among the methods (P > 0.05). Compared with the two other methods, the meteorological yield series obtained by the HP filter method matched well with climatic variations, followed by the exponential smoothing method. In conclusion, among the three methods of fitting, the HP filter method was the best for fitting the trend yield of rice in Liaoning Province, followed by the exponential smoothing method and then the Logistic method (which was actually not suitable for fitting the trend yield of rice in Liaoning Province). The research results provided the needed reference for trend yield trend fit analysis.

Effect of planting density on stem characteristics and yield of summer maize in the Hilly Central Sichuan Basin, China

LIU Xiaolin, MA Xiaojun, DOU Pan, HUANG Kecheng, WANG Xinglong, ZHANG Di, KONG Fanlei, YUAN Jichao

2017, 25(3): 356-364. doi: 10.13930/j.cnki.cjea.160822

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Abstract:
Increasing planting density has been one of the most common ways of increasing maize yield. In order to determine the proper planting density of maize in Hilly Central Sichuan Basin (HCSB) in China, an experiment involving 5 planting densities (4.50×10⁴, 5.25×10⁴, 6.00×10⁴, 6.75×10⁴ and 7.50×10⁴ plant·hm^-2) of maize were conducted. The effects of planting density on stalk characteristics and yield of summer maize cultivar 'Zhenghong-505' were investigated. The results showed that plant height, ear height, internode length, length-to-diameter ratio of internode increased with increasing planting density. Also stem diameter, stem diameter coefficient, internode dry weight, internode dry matter weight to length ratio, stalk crushing strength (SCS) and rind penetration strength (RPS) decreased with increasing planting density. There were significant differences the traits except ear height among different planting densities. Compared with planting density of 4.50×10⁴ plant·hm^-2, RPS of the 1st, 3rd and 5th internodes reduced significantly respectively by 27.10%, 22.78% and 30.80% under planting density of 7.50×10⁴ plant·hm^-2. Maize yield increased at first and then decreased with increasing planting density, with a maximum yield under 6.00×10⁴ plant·hm^-2. There was a significant increase in yield (12.02%) under planting density of 6.00×10⁴ plant·hm-2 compared with yield under planting density of 4.50×10⁴ plant·hm^-2. Corncob length, corncob diameter, spike rate, kernel per spike and 1000-seed weight significantly (P < 0.05) decreased with increasing planting density, while the effective panicle and barren tip length significantly increased. Correlation analysis indicated that SCS was significantly positively correlated with RPS (r=0.93^**). Moreover, SCS and RPS had significantly or extremely significant positive correlation with stem diameter, stem diameter coefficient, internode diameter, internode dry weight and internode dry matter weight to length ratio. SCS and RPS had significantly or extremely significant negative correlation with plant height, internode length and length to diameter ratio. A stronger correlation was found between stalk agronomic trait and SCS. Yield per plant had significant or extremely significant positive correlation with stem diameter, stem diameter coefficient, internode diameter, internode dry weight, internode dry matter weight to length ratio, SCS and RPS. It then had significant negative correlation with internode length and length to diameter ratio. Stepwise regression analysis suggested that stem diameter coefficient and internode dry matter weight to length ratio had the most significant influence on SCS. It was concluded that planting density was the primary factor influencing maize stalk characteristics and yield. An appropriate increase in planting density significantly increased maize yield. Then stem diameter coefficient and internode dry matter weight to length ratio were important agronomic indexes for evaluating lodging resistance of maize stalk.

Effect of combined application of humic acid and nitrogen fertilizer on nitrogen uptake, utilization and yield of winter wheat

YUAN Tianyou, JI Jianhua, WANG Junzhong, SUN Xiaomei, YAN Junying, WANG Zhiyong, NIU Junyi

2017, 25(3): 365-372. doi: 10.13930/j.cnki.cjea.160700

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Abstract:
Studies on the effects of combined humic acid and nitrogen fertilizer application on nitrogen (N) uptake, utilization and yield of winter wheat can provide theoretical basis for increasing the productivity of N fertilizers and reducing N fertilizer pollution in the winter wheat-summer maize rotation cropping system. A field experiment was conducted in 2014 at Wolong District in Nanyang City, Henan Province, an area with a predominant winter wheat and summer maize rotation cropping system and drab soils. The experiment was consisted of 6 treatments-no N fertilizer (only P and K fertilizers), conventional fertilization (P and K fertilization with N application rate of 180 kg·hm^-2), single humic acid (3 000 kg·hm^-2), conventional fertilization plus humic acid, conventional fertilization with 15% less N plus humic acid and conventional fertilization with 30% less N plus humic acid. The characteristics of yield and N fertilizer utilization of winter wheat under different fertilization modes were analyzed. The results showed that combined application of humic acid and N fertilizers increased winter wheat yield, and promoted N accumulation and utilization rate. Among treatments, the treatment of conventional fertilization with 15% less N plus humic acid treatment had the best effects. Winter wheat yield, grain N content, grain N accumulation, aboveground total N accumulation, N use efficiency and net income increased. Compared with conventional fertilization, yield increased by 4.96%, N use efficiency by 23.42% and net income by 2.18%. However, the 30% less N treatment reduced winter wheat productivity and revenue. Thus, on the basis of the application of humic acid, the appropriate dose of N fertilizer was recommended to ensure high productivity and income. The conventional fertilization with 15% less N plus humic acid was the best fertilization mode in the study area. The results are beneficial for improving productivity efficiency of agricultural, resources and environmental protection.

Physiological response of sugar beet (Beta vulgaris L.) to water deficit at sugar accumulation stage under drip irrigation

LI Yangyang, FEI Cong, CUI Jing, WANG Kaiyong, MA Fuyu, FAN Hua

2017, 25(3): 373-380. doi: 10.13930/j.cnki.cjea.160669

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Abstract:
Understanding the effects of water deficit on the physiological characteristics of sugar beet is essential for the determination of the minimum soil water content during sugar accumulation stage. Thus a field experiment was conducted to study the changes in leaf photosynthetic characteristics, water stress index, recovery degree, yield and technological sugar yield under drought resistance and rehydration cultivation. The study included three soil water content levels in the 0-40 cm depth-70% of field capacity (T1), 50% of field capacity (T2) and 30% of field capacity (T3). The results showed that the yield and technological sugar yield under T3 were significantly higher than those under T1 and T2 by 51.34%, 51.47%, and 36.72%, 39.48%, respectively. Leaf proline and soluble sugar contents were sensitive to water deficit before rehydration. Moreover, both leaf proline and soluble sugar contents were positive correlated with the degree of water deficit. Rehydration after water stress showed positive compensation effect on membrane permeability, antioxidant enzyme activities and osmotic adjustment substances contents of sugar beet. The enhancements were observed in leaf malondiadehyde content, peroxidased and catlase enzyme activities, proline and soluble sugar contents which favored increased osmotic adjustment. Therefore, prompt supplemental irrigation was needed when soil water content dropped to 30% of field capacity during sugar accumulation stage, which had a compensation effect on sugar beet under water deficit cultivation. It was helpful to work toward high yield and quality of sugar beet under drip irrigation in arid areas.

Differentially expressed proteins in response to low temperature in Brassica campestris 'Long-you No. 7' seedlings

CHEN Qi, YUAN Jinhai, LIU Zigang, SUN Wancang, FANG Yan, ZHAO Xinwang, MA Li, PU Yuanyuan, ZHAO Yanning, ZENG Xiucun

2017, 25(3): 381-390. doi: 10.13930/j.cnki.cjea.160581

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Abstract:
Successful northward expansion of winter rapeseed depends on breeding of super cold-resistant varieties. The 'Longyou' series of Brassica campestris varieties is cold-resistant, but this mechanism has still not been fully understood. In this study, seedlings of B. campestris 'Long-you No. 7' variety (a strong cold-resistant variety) was used to determine the cold-resistance mechanism at proteomic scale. The TCA (trichloroacetic acid)-acetone precipitation method was used to extract total protein in leaves before and after low temperature stress (4℃ for 7 days). Then the protein extraction method and different pH range of IPG gels was improved and optimized. Furthermore, by using the two-dimensional gel electrophoresis and mass spectrometry methods, the differentially-expressing patterns of total protein in the leaves of 'Long-you No. 7' at five-leaf stage under low temperature stress was determined. The results showed that the average concentration of leaf protein extracted with the improved protein extraction solution containing DDT (DL-Dithiothreitol) and PVPP (crosslinking polyvingypyrrolidone) increased by 3.42 μg·μL^-1 and the desalting time deceased by 1.14 h. This indicated an improvement in extraction efficiency by the addition of DTT and PVPP to protein extraction solutions. In addition, the addition of protease inhibitor containing PMSF (phenylmethanesulfonyl fluoride) to protein extraction solutions led to the detection of more protein categories; further increasing the number of protein spots by 11.2% (661 versus 587) in the gel pattern. It was also found that by using 17 cm IPG gel (which isolated proteins in a better way) with pH range of 4-7 at vertical electrophoresis stage, higher quality proteomic maps with good repeatability were produced. By using PDQuest 8.0 software, proteomic expression profile of a strong cold-resistant 'Long-you No. 7' seedling before and after low temperature stress was analyzed and a total of 15 differentially-expressed protein spots detected, which was supposedly related to the response to low temperature stress. After further analysis of the protein spots by mass spectrometry, 11 different categories related to low temperature stress were identified, including photosynthesis protein, sugar metabolism protein, material transportation protein and adversity response protein. The findings also showed that the expression level of leaf proteins in 'Long-you No. 7' seedlings differed obviously. Such differentially-expressed proteins were probably critical for cold resistance of B. campestris, which provided a useful basis for further research.

Effects of row spacing and maize variety on abundance and function of denitrifying bacterial flora in maize rhizosphere

SONG He, JIN Wenjun, CHE Zhao, CAO Wenchao, DONG Zhaorong, WANG Chengyu

2017, 25(3): 391-399. doi: 10.13930/j.cnki.cjea.160882

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Abstract:
Denitrification is a key pathway of nitrogen loss in the rhizosphere. It is unknown whether changes in variety and row spacing of crop have any impacts on denitrification in the rhizosphere. Thus this study compared the differences in abundance and function of denitrifiers in the rhizosphere of different maize varieties and row spacings. The aim of the study was to provide scientific basis for reducing rhizosphere denitrification losses and improving nitrogen use efficiency. Based on data from two independent field experiments, the study investigated the effects of five maize varieties ('Xundan 20', 'Annong 8', 'Zhengdan 958', 'Pinyu 18' and 'Longping 206') and four row spacings (20 cm, 30 cm, 40 cm and 50 cm) on denitrification capacity, abundance of denitrifiers, N₂O/(N₂O+N₂) ratio and soil respiration in the rhizosphere using biochemical and molecular microbiological methods. Denitrification capacities in the rhizospheres of 'Xundan 20', 'Annong 8' and 'Zhengdan 958' were significantly lower than those in the rhizosphere of the other maize varieties. With decreasing row spacing, denitrification capacity in rhizosphere soil obviously increased. The abundances of nirS-denitrifiers in the rhizospheres of 'Longping 206' and 'Pinyu 18' were significantly higher than those in the rhizospheres of the other maize varieties. The abundances of nirK-and nosZ-denitrifiers in the rhizospheres of 'Xundan 20' and 'Annong 8' were the highest. In all the row spacings, 20 cm had the highest abundances of nirS-and nirK-denitrifiers. As for nosZ-denitrifiers, the most abundance was found in the 40 cm row spacing treatment. The change of variety had a certain impact on N₂O/(N₂O+N₂) ratios (e.g. 'Annong 8' had the lowest ratio), but the effect of row spacing was no significant. Correlation analysis showed there was a significantly positive correlation between denitrification capacity and soil respiration or the abundance of nirS-denitrifiers. But not significant correlation was found between denitrification capacity and the abundances of nosZ or nirK-denitrifiers. This suggested that differences in the abundances of nirS-denitrifiers and organic carbon in the rhizosphere were the dominant factors causing the changes in denitrification capacity. Changes in variety and row spacing could affect denitrification of maize rhizosphere as well. The screening of varieties with low denitrification loss and the regulation of denitrification processes in the rhizosphere were effective ways of reducing rhizosphere denitrification loss and improving crop nitrogen use efficiency.

Effect of cotton stalk biochar application on soil microflora of continuous cotton cropping under use of antagonistic actinomycetes

MA Yunyan, XU Wanli, TANG Guangmu, GU Meiying, XUE Quanhong

2017, 25(3): 400-409. doi: 10.13930/j.cnki.cjea.160583

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Abstract:
As an important cash crop, cotton usually continuously cropped for a long-term, which causes an imbalance of soil microbial ecology, incidence of soil-borne disease increase, yield and quality decline, preventing the healthy development of cotton industry. Biochar application can increase soil microbe activity due to its higher porosity, huge specific surface area and ability of nutrient absorption. Biocontrol agents have been found to be effective in adjusting soil environment, alleviating continuous cropping obstacles and controlling soil-borne diseases. However, it is not clear how the biochar affects soil microbe of continuously cropped cotton field under the application of the biocontrol agent of antagonistic actinomycetes. In this paper, a lab incubation experiment was conducted to study the effects of cotton stalk biochar application on soil microflora of continuous cotton cropping under use of antagonistic actinomycetes. Based on antagonistic actinomycetes application, the experiment was designed in 4 treatments of biochar rate-0 g·kg^-1 (control), 25.0 g·kg^-1, 50.0 g·kg^-1 and 100.0 g·kg^-1. The soil microflora was investigated after 15 days of incubation. The results showed that:1) cotton stalk biochar influenced soil microflora under the application of antagonistic actinomycetes. Compared with control, cotton stalk biochar significantly increased the number of bacteria, actinomycetes and fungi in the soil. Applications with 25.0 g·kg^-1 biochar increased bacteria/fungi (B/F) and actinomycetes/fungi (A/F) by 5 271.2% and 30.8% (P < 0.05), respectively. 2) The number of antagonistic actinomycetes significantly increased with increasing application of cotton stalk biochar. Applications with 100.0 g·kg^-1 biochar into the soil significantly increased antagonistic actinomycete population by 2 672.8% (P < 0.05). Cotton stalk carbon served as a potential carrier of biocontrol actinomycetes. 3) Antagonistic actinomycetes with cotton stalk biochar changed the number and proportion of dominant microorganisms in the soil, and especially improved the number and proportion of Bacillus. The number and proportion of Streptomyces under the treatment with 100.0 g·kg^-1 biochar into the soil were significantly higher than those of control treatment, while the number and proportion of Micromonospora were lower. The number of Aspergillus oryzae, Aspergillus niger and Trichoderma koningii increased while the proportions decreased. Therefore, the application of antagonistic actinomycetes and cotton stalk biochar increased the number of biocontrol agent and enhanced disease-controlling and growth-promoting abilities of antagonistic actinomycete, and also improved the structure of soil microbial community. It was concluded that the application of antagonistic actinomycetes and cotton stalk biochar had the potential to alleviate the adverse effects of continuous cropping cotton.

Phosphate solubilization activities and action mechanisms of two phosphate-solubilizing bacteria

CHEN Danyang, LI Hanquan, ZHANG Binghuo, ZHA Daiming, YANG Jianyuan

2017, 25(3): 410-418. doi: 10.13930/j.cnki.cjea.160667

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Abstract:
Phosphate-solubilizing bacteria play an important role in increasing soluble phosphorus content in soils and utilization efficiency of phosphatic fertilizers. Halo zone on agar plate was used to screen solubilizing-phosphate bacteria and the molybdenum antimony resistance colorimetric and disodium phenyl phosphate methods were used to analyze solubilizingphosphate activities and phosphatase activities of the bacteria. The organic acids produced by solubilizing-phosphate bacteria were analyzed using thin layer chromatography (TLC). The taxonomic status of the solubilizing-phosphate bacteria was determined on the basis of physiological and biochemical characteristics and phylogenetic analysis of 16S rRNA gene sequences. The aim of the study was to select bacteria strains solubilizing both inorganic and organic phosphate, and to explore their phosphate solubilization activities and mechanisms. The results showed that two bacteria (designated as JXJ-11 and JXJ-15 strains) exhibited higher activities in solubilizing phytin and the soluble phosphorus contents in the culture broths increased respectively by 219 mg·L^-1 and 216 mg·L^-1 after three days of incubation. The two strains showed lower activities of solubilizing calcium phosphate and the highest soluble phosphorus contents in the culture broths were only 21.79%-30.37% of phytin in media. Both JXJ-11 and JXJ-15 strains secreted acid, neutral and alkaline phosphatases to degrade insoluble phosphorus and probably produced organic acids (e.g., propionic and succinic acids) which reduced pH values of culture broths while increasing soluble phosphorus contents. Both JXJ-11 and JXJ-15 strains were gram-stain negative, non-endospore forming and positive for the production of hydrogen sulfide. While 16S rRNA gene sequence of JXJ-11 strain was closely related to Sphingomonas melonis DAPP-PG 224^T and S. aquatilis JSS7^T (99.79%), JXJ-15 strain was closely related to Klebsiella pneumoniae subsp. pneumoniae DSM 30104^T (99.73%). Based on the results above, JXJ-11 and JXJ-15 strains were identified as members of the genus Sphingomonas and Klebsiella, respectively. The action mechanisms of phosphate solubilization of JXJ-11 and JXJ-15 strains included secretion of organic acids and phosphatases. The study showed that JXJ-11 strain had a potential application value in developing microbial phosphatic fertilizers.

Evaluation of agricultural land suitability for soybean cultivation in the Sanjiang Plain, Northeast China

BU Kun, WANG Zhiliang, ZHANG Shuwen, YANG Jiuchun

2017, 25(3): 419-428. doi: 10.13930/j.cnki.cjea.160342

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Abstract:
The Sanjiang Plain is one of the most important grain production base in China. The importance of the plain could increase with the promulgation of policies that encourage farmers to cultivate soybean to adapt to the global climate change and CO₂ concentration rise. In order to make full use of the advantages in climate and soil conditions, there is the need for rational allocation of soybean cultivation areas in the Sanjiang Plain. In this paper, firstly, we carried out climate suitability evaluation for the cultivation of soybean based on climate and soil inventory with the GAEZ framework of FAO/IIASA. Then, we used soil thickness, soil texture, soil pH, land drainage and flooding conditions as indicators of soil suitability evaluation and the results of the analysis were degraded by Albic bleach soil in the Sanjiang Plain. Finally, the results of the agricultural land suitability evaluation were obtained by overlapping layers in GIS at the grid scale (30 m×30 m) and Suitability Index (S_I) calculated to geospatially compare soybean cultivation in the study area. The results showed that:1) most parts of the Sanjiang Plain was suitable for soybean cultivation, except for areas with slope≥30%.2) About 8.5×10⁴ km² (78.75% of the plain) was suitable for soybean cultivation, especially gentle slope (2%-5%) and undulating slope (5%-8%) areas along the bank of Songhua, Woken and Muleng Rivers with good soil texture and high drainage. 3) Nine counties with the highest S_I (≥70%) included Boli, Yilan, Tangyuan, Jamusi, Jixian, Huachuan, Youyi, Suibin and Fujin. Then 10 counties (Tongjiang, Huanan, Hulin, Baoqing, Fuyuan, Qitaihe, Luobei, Jidong, Raohe and Shuangyashan) had higher S_I (60%-70%); Hegang, Mishan, Jixi and Muleng counties had the lowest S_I (S_I≤60%). 4) For its simple and objective evaluation procedure, the GAEZ framework was applicable in locally distinguishing spatial differences in soybean cultivation areas needed in rational land allocation.

Delineation of key areas of cultivated land quality improvement in Lulong County based on restriction degree

ZHANG Jie, ZHAO Ruidong, TIAN Chao, QIU Rui, SHI Bo'an, YANG Jinze, CHEN Qingfeng, CHEN Yaheng

2017, 25(3): 429-440. doi: 10.13930/j.cnki.cjea.160747

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Abstract:
Cultivated land is not only an essential precondition for national food security, but also a material foundation for social security and sustainable development. The overall quantity of cultivated lands in China is large, but quality level has remained low. In order to design a definite direction for cultivated land consolidation and planning for different areas in Lulong County of Qinhuangdao, Hebei Province, this study established a quality evaluation indicator system for cultivated lands and determined the composite types of the limiting factors based on a score factor identification method. The study also introduced the obstacle degree model to modify the limiting factor combination used to delimit the key areas of cultivated land quality improvement. The results showed 15 981 plots of cultivated lands with high level limiting factors and 95 limiting factor combination types in Lulong County, which totally accounted for 43 909.71 hm² of cultivated croplands. After the introduction of an modified obstacle degree model, cultivated land of Lulong County was divided into 5 dominant limiting factor areas consisting of road accessibility dominated region, terrain slope dominated region, irrigation guaranteed dominated region, farmland shelter belt ratio dominated region and effective soil thickness dominated region. The biggest area (37 680.91 hm²) was mainly limited by farmland shelter belt ratio, accounting for 85.81% of the total cultivated area and mainly distributed across Lulong, Yanheying and Shuangwang Towns. The second-biggest area (3 861.32 hm²) was mainly limited by effective soil thickness, which was mainly distributed across Yinzhuang Town. The area limited mainly by road accessibility was 1 876.16 hm² and was mainly distributed across Shuangwang Town. The area limited mainly by probability irrigation was 319.44 hm², which was mainly distributed across Yanheying Town. The smallest area limited mainly by terrain slope was 171.87 hm², making up only 0.39% of the total cultivated area and mainly distributed across Liutiangezhuang Town. Based on the limiting factors in the main areas, the dominant limiting factors of cultivated land quality in Lulong County were farmland shelter belt ratio and effective soil thickness. Then probability irrigation and road accessibility played subsidiary roles in limiting cultivated land quality in the study area. The remediation processes of cultivated land included the strengthening of construction of shelter forest and the increase of effective soil thickness and improvement of soil fertility through enhancing farmland establishment and construction of feeder roads. The study provided technical support for planning consolidation strategies in hilly and mountainous areas and defining each section in the improvement of cultivated land quality. It also provided scientific basis for future farmland regulation in the region.

Soil acidification degree difference and impact factors of subtropical cropland

ZHANG Xiu, ZHANG Liming, LONG Jun, CHEN Hanyue, FAN Xieyu, XING Shihe, XU Fuxiang

2017, 25(3): 441-450. doi: 10.13930/j.cnki.cjea.160723

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Abstract:
Soil pH is an important indicator of cropland soil fertility and quality. Decline in soil pH is a vital problem in soils of intensive agricultural systems in China, which heavily obstructed crop growth and improvement of ecological environments. Thus accurate knowledge on the degree of acidification and its causes of regional cropland soils is crucial for the enhancement of the quality of cropland soils and sustainable development of agriculture. In this study, data on topsoil attributes collected from 36 777 sampling sites in the second soil survey in 1982, 236 445 sampling sites of soil fertility investigation for fertilization in 2008, average annual temperature and precipitation for 1980-2008 in Fujian Province were used to establish a 1:250 000 map of relevant cropland soil attributes database in ArcGIS software. This database, containing a total of 34 593 patches, was used to study the extent of acidification, and combined with the Grey slope correlation analysis model to explore the causes of cropland soils acidification in the province. The aim of the study was to lay the scientific basis necessary for understanding soil acidification regulation. The results showed that the area of acidification during the studied period accounted for 67.60% of the total area of croplands in the province. Also the areas with strong, moderate and low acidifications accounted for 0.83%, 18.26% and 48.52% of total croplands in the province, respectively. Analysis on prefectural city scale showed that strongly acidified croplands were mainly distributed across Longyan City and Quanzhou City, accounting respectively for 86.88% and 8.39% of total strongly acidified croplands in the province. Moderately acidified farmlands were mainly distributed across Nanping City, Longyan City and Quanzhou City, accounting respectively for 29.88%, 18.10% and 16.94% of total moderately acidified cropland in the province. The weakly acidified croplands were widely distributed across Fujian Province. On the whole, strongly and moderately acidified farmlands were mainly distributed across the north, southwest and southeast littoral regions of Fujian Province. In terms of soil type, gley paddy soils, percogenic paddy soils and acid purplish soils had significantly acidized in 1980 to 2008, with acidified areas accounting respectively for 82.87%, 72.37% and 69.20% of total gley paddy soils, percogenic paddy soils and acid purplish soils in the province. However, the acidification degrees of percogenic and hydromorphic paddy soils were relatively severe, with the total area of strong, moderate and low acidifications accounting respectively for 98.94%, 84.51% and 87.36% of total acidified cropland area in the province. In terms of land use type, paddy and irrigated fields were significantly acidified, accounting for a high proportion of the study area. Acidified areas accounted respectively for 70.35% and 60.78% of total paddy and irrigated fields in the study area. Grey slope correlation analysis suggested that increasing severity of acid rain, high temperature, high precipitation and high fertilizer input were the main factors contributing to the acidification of croplands in Fujian Province. An effective control approach of cropland acidification in Fujian Province was by strict control the emissions of industrial acidic exhaust gases containing sulfur. It was also necessary to optimize fertilizer management programs by increasing organic fertilizers application and reducing chemical nitrogen and phosphate fertilizers application.

Evaluation of regional drought disaster to maize using WOFOST crop growth model

ZHANG Jianping, WANG Jing, HE Yongkun, CHEN Yanying

2017, 25(3): 451-459. doi: 10.13930/j.cnki.cjea.160677

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Abstract:
Timely and accurate assessment of the impacts of drought on maize in the maize producing areas in Southwest China for regional agricultural production planning has become increasingly important with more frequent and severe drought events. In order to effectively study the impact of drought on crop production, the assessment method of agricultural meteorological disaster should be expanded. This study evaluated the application of WOFOST model using field experimental data of maize and the parallel daily meteorological data collected at eight typical stations in Southwest China. The WOFOST model was improved for the phenology and photosynthesis modules before application. Based on the improved crop model, the historical impacts of drought on maize production in terms of change trend in maize yield for typical drought years were analyzed. The results showed that the normalized root mean squared errors (NRMSE) between the simulated and observed maize phenology reduced from the range of 3.25%-6.95% to 1.48%-3.07%, R² increased from 0.57-0.79 to 0.63-0.99 and the average simulation precision increased from 74.12% to 78.9%. NRMSE between simulated and observed maize yields reduced from the ranges of 7.88%-11.99% to 3.07%-6.79%, R² increased from 0.52-0.93 to 0.77-0.98 and the average simulation precision increased from 75.7% to 80.95%. The average simulation precisions of maize yield were 69.8%, 75.9% and 78.1% in typical drought years of 1987, 1992 and 2006, respectively. The above results showed that the simulation precision of the phenology and yield of maize improved significantly and the model was therefore fully applicable in simulating the impacts of drought on maize production. The study provided a scientific technique for the drought assessment on regional maize production in Southwest China.

Simulation of non-point source solute nitrogen transport in drainage ditches under water-sediment-aquatic plant synergy

LI Qiangkun, HU Yawei, SU Xin

2017, 25(3): 460-466. doi: 10.13930/j.cnki.cjea.160798

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Abstract:
Along highlighted water environmental issues and gradual evolution of point source pollution (PSP) such as industrial waste, agricultural non-point source pollution (AGNSP) due to non-scientific applications of fertilizers and pesticides has had an increasing attention in recent years. On the basis of strengthening field "source control", making the best use of agricultural drainage ditch/pond system (interception process) is critical for agriculture non-point source pollution control and management. Drainage ditches have compound ecosystem structures, which are consisted of water-sediment-plant synergy. Migration and transformation of non-point source solute is important in the study of interception, control and management of agricultural non-point source pollution in drainage ditches. However, non-point source solute transformation processes in each medium in water-sediment-plant system of farmland drainage ditch have remained largely unclear. Based on the analysis of ecological structure and drainage ditch characteristics, this paper described the transformation of non-point source soluble nitrogen in water-sediment-plant system of farmland drainage ditch. In combination with the characteristics of farmland drainage ditch water pollution migration, a model of agricultural water pollution migration in drainage ditch system was constructed. The model was based on continuity equation for flow and pollutants migration. It was used to test, monitor and advance a quantitative method of calculation of the effect of different water-sediment-plant media on attenuation degree of non-point source pollutant in water body. Using Qingshui drainage ditch in the People's Victory Canal Irrigation District in Henan Province as a case study, the model was used to calculate the parameters of a field experimental ditch loaded with ammonia nitrogen and nitrate nitrogen pollutants. The results showed that the simulated and measured values fitted well. The simulation efficiency coefficient of ammonia nitrogen was 0.87 and that of nitrate nitrogen was 0.93. The results demonstrated that the model was available and effective for the simulation of drain pollution in ditches in agricultural farmlands.

2017 Vol. 25, No. 3