中国生态农业学报(中英文)

Characteristics of soil respiration on typical cropland slope in mollisol region of Northeast China

HUANG Chengcheng, WANG Yingchun, ZHANG Jianfei, WANG Ligang

2018, 26(1): 1-7. doi: 10.13930/j.cnki.cjea.170569

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Abstract:
The characteristics of soil respiration in cropland slopes are different from those in cropland plains. In order to accurately evaluate greenhouse gases emission in Northeast China farmland, it was necessary to study the patterns and factors influencing soil respiration in different cropland slopes. The study was conducted on a typical cropland slope in a mollisol region in Northeast China. An entire cropland slope was divided into four slope positions based on change in gradient-summit, shoulder-slope, back-slope and toe-slope. The LI-8100 probe was used to monitor soil respiration throughout the maize growing period. Water content and temperature of the surface soil (0-20 cm soil layer) were respectively measured using soil moisture meter and thermometer. The relationship between soil carbon dioxide (CO₂) flux and the impact of temperature, soil moisture content were then analyzed for different slop positions (summit, shoulder-slope, back-slope and toe-slope). The study laid the basis for scientific evaluation of soil respiration and carbon balance in mollisol in cropland slopes. The results showed that CO₂ flux in summer was higher than in spring and autumn. Peak soil respiration occurred during the period from maize silking to tasseling, which was from July 3 to August 23 in the study area. During this period, the cumulative respiration was 58.7%-59.9% of total soil respiration for the whole growing period of maize across the four slope positions, indicating it was the main period of soil respiration in mollisol regions in Northeast China. The peak rate of soil respiration was significantly different in each slope position (P < 0.05). It was significantly higher in the toe-slope position[7.56 μmol(CO₂)·m^-2·s^-1] than at the summit[5.60 μmol(CO₂)·m^-2·s^-1], shoulder-slope[6.08 μmol(CO₂)·m^-2·s^-1] and back-slope[6.47 μmol(CO₂)·m^-2·s^-1]. The results showed that soil respiration rates among different slope positions in typical mollisol regions were significantly different, especially in summer. CO₂ flux had a positive, linear correlation with soil temperature for all the slope positions (P < 0.05). The exponential equation best expressed the relationship between soil temperature and soil respiration rate. Then temperature sensitivity (Q₁₀) was the strongest for the back-slope position, compared with the others. There was an insignificant correlation between soil respiration and soil volumetric water content. These results indicated that change in soil temperature significantly influenced soil respiration rate. The cumulative emission of CO₂ in toe-slope[523.97 g(CO₂-C)·m^-2] was 18.5%, 22.8% and 34.9% higher than in back-slope[443.13 g(CO₂-C)·m^-2], shoulder-slope[426.81 g(CO₂-C)·m^-2] and summit[388.50 g(CO₂-C)·m^-2], respectively. This was caused by the migration and redistribution of organic carbon, the change in soil bulk density, and the related effect on soil under the different environmental factors. The results of the study suggested that it was necessary to consider the respiration characteristics of different slope positions in order to limit any deviations in the monitoring results based on cropland plains respiration in the scientific evaluation of soil respiration on cropland slopes.

Effect of transgenic rice straw return to soil on nitrification and denitrification microbial community

WANG Peixuan, XU Yan, SONG Yana

2018, 26(1): 8-15. doi: 10.13930/j.cnki.cjea.170794

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Abstract:
The cultivation of genetically modified plants may have the potential to alter microbial community structure and function in soils through root exudates and plant residues. Ammonia-oxidizing bacteria or denitrifying bacteria are the key microbes for nitrification or denitrification. A change in community structure of ammonia-oxidizing bacteria or denitrifying bacteria can affect the conversion and utilization of nitrogen in soil. The purpose of this study was to explore the possibility of transgenic rice to induce change in nitrogen transformation and N₂O emission in paddy soils. In the study, the abundance and composition of ammonia-oxidizing bacteria or denitrifying bacteria in paddy soils under straw return to soil under cry1Ac/cpti transgenic gene rice 'Kf8' or non-transgenic rice 'Mh86' were analyzed by real-time PCR and denaturing gradient gel electrophoresis (DGGE) based on amoA gene or nirS gene. The results showed that there were no differences in the abundance of amoA gene or nirS gene in the soil with returned transgenic rice 'Kf8' straw and non-transgenic rice 'Mh86' straw. The abundance of amoA gene in the 0-10 cm soil layer was significantly (P < 0.05) higher than that in the 10-20 cm and 20-30 cm soil layers under degraded transgenic rice 'Kf8' straw or non-transgenic rice 'Mh86' straw. The abundance of nirS gene in the soil increased with the time of returned straw to soil for either transgenic rice 'Kf8' or no-transgenic rice 'Mh86'. At the same time, the Shannon-Weiner index and composition of ammonia-oxidizing bacteria or denitrifying bacteria in the soil under degraded transgenic rice 'Kf8' straw were similar to those under degraded non-transgenic rice 'Mh86' straw. The composition of ammonia-oxidizing bacteria in the soil was significantly correlated with the time of rice straw return (P=0.002). Also the abundance of denitrifying bacteria was significantly correlated with the time of rice straw return (P=0.002) and depth of soil (P=0.024). The findings demonstrated that there was no significant effect of returned cry1Ac/cpti transgenic rice straw to soil on key microbial com-munities for nitrification or denitrification in soil. In terms of soil microbial community, there was no signiifanct effect of returned cry1Ac/cpti transgenic rice straw to soil on nitrogen transformation and N₂O emission in paddy soils.

Evaluation of pollination service supply and demand of agricultural landscape in Changping District, Beijing

SONG Xiao, WU Panlong, WANG Fei, LI Xiang, SUN Renhua, ZHANG Xuzhu, XIA Bohui, LIU Yunhui

2018, 26(1): 16-26. doi: 10.13930/j.cnki.cjea.170566

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Abstract:
The diversity of bees has declined in recent years around the world. This has raised concerns about pollination service, which is closely linked with sustainable agricultural production. To understand the supply and demand of regional pollination service and laid the basis for developing a regional pollination management strategy, we investigated seven common habitat types, which were forest, woodland, grassland, orchard, greenhouse, road boundary, field margin, and one non-habitat land in Changping District of Beijing in 2016. The data including bee (species, flying distance, nesting preference and active season), vegetation (vegetation composition, flowering season, nectar/pollen resources), nesting suitability (soil compaction) and crop area were collected. The supply of pollination service in the study area was evaluated by using the InVEST model, which was based on species composition, flight distance, nesting preference and activity season of wild bees. The model also used data of plant resources and nesting suitability in the habitat to estimate the dependent degree of crops on pollination. The demand for pollination service was evaluated based on planting area and dependence on pollination service of crops. Furthermore, the match between pollination service supply and demand was studies by stacking the levels of supply and demand. The results showed that natural forests were the most suitable habitat for wild bee production, followed by woodlands, grasslands and border habitats. Orchards too were wild bee habitats and also had high demand for pollination service. Greenhouse barely provided pollination service, but had a high demand for it. The supply and demand match results showed that in Changping area, pollination service supply exceeded demand. The areas where supply level was higher than demand level accounted for 34.2%, mostly distributed in mountain areas. The areas with the highest supply and lower demand for pollination service was worthy for protection. The areas with lower supply than demand accounted for 13.9% and were distributed in plain regions near mountains. Although such areas had a relatively high supply, demand was the highest. Areas with the same supply-demand accounted for 51.9%, distributed in plain areas far from mountains. In these areas, the supply and demand for pollination service were basically in balanced match because of the high proportion of semi-natural habitats. Finally, some management strategies were suggested to improve pollination service in the study area. For the areas with higher supply and medium/lower demand (key protected region), it was suggested to develop organic agricultural with less management to protect habitat. For medium/lower supply and higher demand areas (key improved and generally improved regions), it was necessary to improve pollination service by breeding bee and increase nat-ural/semi-natural habitat, and strengthen connectivity among habitats through ecological corridor construction. For the area with balanced supply and demand (key maintained, and generally maintained regions), decreasing management intensity of agricultural area and increasing connectivity among habitats were important for keeping sustainable pollination service supply.

Potential distribution of Actinidia chinensis in China and its predicted response to climate change

WANG Rulin, LI Qing, HE Shisong, LIU Yuan

2018, 26(1): 27-37. doi: 10.13930/j.cnki.cjea.170557

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Abstract:
Kiwifruit (Actinidia spp.), belonged to Actinidiaceae, is a type of perennial deciduous woody liana and an important class of berry fruit. With rich sugar, protein, amino acids, vitamins and especially high vitamin C content, the kiwifruit is known as "the king of the fruit" and has a good market prospect. A. chinensis is a species endemic in China with a fast-expanding planting area due to its unique subtle flavor and high economic value. Optimization of planting scale and distribution of the crop has been the major concern for regional planning. The objective of this study was to test and determine the possibility of using the MaxEnt (the maximum entropy) model to simulate and predict future large-scale distribution of A. chinensis. Based on current environmental factors, three future climate scenarios suggested in the IPCC fifth report and current distribution sites of A. chinensis, we used the MaxEnt model in combination with ArcGIS to predict the potential geographic distribution and trend of change of A. chinensis in China. The dominant factors were chosen by using the Jackknife test and the Receiver Operating Characteristic (ROC) curve was used to evaluate the simulation. The results showed that high value of area under curve (AUC) denoted good results which significantly differed from random predictions. Based on the evaluation criterion, the accuracies of the predictions of A. chinensis potential distribution in the current and future periods were excellent. The predicted result of the MaxEnt model was imported into ArcGIS10.0 for further analysis and showed that under present climatic conditions, the total suitable area was 26.92% of the total land area in China. The potential distribution was highly consistent with the locations of specimen records and field surveys. The highly suitable areas were in Sichuan, Shaanxi, Chongqing, Hubei, Guizhou, Zhejiang, Hunan, Anhui, Henan, Jiangsu and Gansu Provinces. The areas of highly suitable habitat in the main producing provinces were analyzed statistically. The results showed that under the current conditions, the most suitable area for A. chinensis cultivation was 1.01×10⁶ km², accounting for 38.94% of the total suitable areas. The moderately suitable areas were in Henan, Hubei, Anhui and Shandong Provinces, with the area of 6.79×10⁵ km², accounting for 26.26% of the total suitable areas. Comparison of future suitable areas with current suitable areas showed that areas of high suitability increased under scenarios RCP2.6 and RCP4.5, but decreased under scenario RCP8.5. Under scenarios RCP4.5 and RCP8.5, the mean center of highly suitable area of A. chinensis moved northward. The result showed that the MaxEnt model was highly reliable in determining not only the range of geographic distribution of A. chinensis, but also in identifying dominant environmental factors driving the geographic distribution. Whereas climate was a decisive factor in species distribution, change in distribution pattern of species was the most direct effect of climate change. The results provided a critical reference base for A. chinensis plantation pattern and countermeasures to cope with climate change in China.

Suitability analysis of key potato growth stages in Inner Mongolia under climate change

JIN Linxue, LI Yunpeng, LI Dan, YAN Weixiong, WU Xiangdong

2018, 26(1): 38-48. doi: 10.13930/j.cnki.cjea.170474

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Abstract:
Inner Mongolia is the main potato planting area in China. It is therefore of practical importance to explore regional suitability of potato in Inner Mongolia under climate change. Based on the climatic suitability model, this paper analyzed the space-time characteristics of climate suitability for potato cultivation in Inner Mongolia using daily meteorological data (average temperature, maximum temperature, minimum temperature, precipitation, sunshine hours, wind speed, relative humidity and atmospheric pressure) from 119 weather stations during the period 1961-2015. This period was divided into two sub-periods (1961-1990 and 1991-2015) to calculate the suitability of climate for potato critical growth period (from flowering to harvesting) and to analyze the spatial and temporal variations of potato climate suitability. The results showed that average climate suitability index of potato growth from flowering to harvesting in 1961-2015 was 0.62, confirming that climatic conditions were suitable for growing potato in Inner Mongolia. The suitability index of sunshine hours was highest and that of precipitation lowest. This further illuminated that light and heat conditions in the region were better than water condition, and water was the main limiting factor of potato cultivation in Inner Mongolia. For the spatial distribution, the trend in temperature suitability tracked a low-high-medium curve from west to east. The suitability of precipitation was better in the southeast than in the northwest. Also the suitability of sunshine hours was high in the west and low in the east. For the comprehensive suitability of climate based on the above three factors, high-value areas were distributed in the east of Yin Mountain and the south of Daxing'anling Mountain regions, while the low-value areas were in the west of Inner Mongolia. Then for the time scale, the paper analyzed the annual changes in climatic suitability. Most of the area showed an uptrend in climate suitability for 1961-1990, except the north-east and north-west of Inner Mongolia. However, there was a significant decline in climate suitability in most of Inner Mongolia during 1991-2015. For the investigated 55 years (1961-2015), there were different climatic trends/indexes in the growth period form flowering to harvesting of potato in different regions, driven by climate change in Inner Mongolia. The comprehensive climatic suitability increased little in the southeast of Yin Mountain, northwest of Yin Mountain, the Hetao Irrigation District and the Alxa League, while other regions showed a decreasing trend. In general, there was a decreasing trend in climate suitability for potato from flowering to harvesting in Inner Mongolia, which occurred at an average rate of 0.004 0·(10a)-1. The suitability of temperature and precipitation declined, while sunshine hour suitability basically flattened, which was not good for potato growth in the region. Therefore, there was the need to strengthen moisture and temperature managements during the period from flowering to harvesting of potato. The results of the study reflected the overall condition for the cultivation of potato in Inner Mongolia and also provided the necessary references for the efficient utilization of climatic factors.

Use of microorganisms in controlling parasitic root weed Orobanche spp.

CHEN Jie, MA Yongqing, XUE Quanhong

2018, 26(1): 49-56. doi: 10.13930/j.cnki.cjea.170500

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Abstract:
Parasitic root weed Orobanche spp. has already severely constrained the development of agriculture in many areas around the world and it is therefore urgent to develop effective control measures of Orobanche spp. As this parasitic root weed has a specific life cycle and is highly intimate to its host plants, it is difficult to develop an ideal control measure based on traditional practices. Up till now, there has been no measure to effectively control Orobanche spp. to make it completely harmless to host plants and easily applicable at large field scale. Among the control measures available, the use of micro-organisms has increased concerns. In this paper, national and global efforts to control Orobanche spp. by the use of micro-organisms and the mechanisms of the control measures are summarized. Until now, research on biocontrol of Orobanche spp. by the use of micro-organisms has focused on pathogens of Orobanche spp., such as Fusarium spp. and symbiotic bacteria (such as Rhizobium spp.) of host plants. The mechanisms of the use of micro-organisms to control Orobanche spp. have involved in two ways:one is to secrete metabolites that directly inhibited the germination and growth of Orobanche spp. or to indirectly affect the germination of Orobanche spp. by the degradation of the chemical compounds which stimulated the germination of Orobanche spp.; another way is to indirectly affect the parasitic behavior and growth of Orobanche spp. by enhancing host plant resistance against Orobanche spp. Furthermore, the possibility and research advances by the use of soil-borne antagonistic micro-organisms against soil-borne plant pathogens in controlling weedy Orobanche spp. have been discussed. Both soil-borne plant pathogens and Orobanche spp. first infected plant roots underground and then damaged normal growth of the plants. Resistances of plants to soil-borne plant diseases were similar to those of Orobanche spp. Thus, micro-organisms that isolated from soils and controlled soil-borne plant diseases may also have the potential to control parasitic root weed Orobanche spp. We screened out one actinomycete strain (Streptomyces enissocaesilis Sveshnikova) and one actinomycete strain (Streptomyces pactum Bhuyan B.K.) from soil-borne mic-organisms that against soil-borne plant diseases. These two strains effectively controlled O. cumana Wallr. and O. aegyptiaca Pers., respectively, in pot experiments. The application of S. pactum inoculum in field experiment reduced the epigaeous number of O. aegyptiaca and increased the yield of tomato, simultaneously. In conclusion, the use of micro-organisms to control parasitic root weed Orobanche spp. is an effective measure.

Progress and perspective of legume-gramineae rotations

ZENG Zhaohai

2018, 26(1): 57-61. doi: 10.13930/j.cnki.cjea.171058

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Abstract:
Legume-gramineae rotation is an important technology for sustainable agriculture, as well as an essence of traditional agriculture in China. The rotation of leguminous and gramineous crops is of great significance in reducing the use of synthetic N-fertilizer and pesticides in agricultural production system, maintaining soil biodiversity, and improving the utilization efficiency of nutrient resources. In this paper, we reviewed the importance of legume-gramineae rotation in the view of the current agricultural situation and issues. Progress on legume-gramineae rotation effects on yield effect, nitrogen effect on crop yield, pest and disease control, and biodiversity increase of farmland were discussed. The major challenges and breakthroughs on legume-gramineae rotation were proposed. Work could be done in the following fields:1) coordinating the rotation crop stubble, developing and promoting the integrated management techniques of legume-gramineae rotation, and improving the comprehensive effects of crop rotation system; 2) designing long-term experiments to investigate the frontier issues of agricultural ecology in response to rotation; and 3) evaluating the ecological effects of crop rotation and establishing a mechanism for ecological subsidies of crop rotation. The role and prospect of legume-gramineae rotation was reviewed in this paper and it is of great importance to the sustainable development of agriculture.

Construction of efficient nitrogen-fixing cropping pattern:Maize/faba bean intercrop with rhizobium inoculation in reclaimed low-fertility soils

MEI Peipei, WANG Ping, LI Long, ZHANG Xuan, GUI Linguo, HUANG Jiancheng

2018, 26(1): 62-74. doi: 10.13930/j.cnki.cjea.170620

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Abstract:
Lighe sierozem in the Ningxia Yellow River Irrigation area is characterized as newly reclaimed soil due to lower fertility and land consolidation. To rational use land resources with environmental friendly way of the soil, leguminous/non-leguminous crops intercropping plus nitrogen-fixing rhizobium is an important measure. In order to construct an efficient nitrogen-fixing cropping pattern in reclaimed lands, the efficiency of Rhizobium species and the inoculation methods were investigated aiming to the construction of a maize/faba bean-rhizobium intercropping systems through the greenhouse and field experiments with newly-reclaimed low-fertility soils. Four Rhizobium leguminosarum biovar viciae (NM353, CCBAU, G254 and QH258) and four inoculation methods (seed inoculation with water absorbent, seed inoculation with water, dip root at 3-leaf stage and seed pelleting & inoculation) were used and the relative advantages determined with respect to crop productivity, aboveground nitrogen acquisition, nodule characteristics, biological nitrogen fixation, etc. The greenhouse experiment results showed that the order of total biomass of intercropped maize and faba bean for different rhizobium was CCBAU > NM353 > G254 > QH258 > intercropping without rhizobium > sole crop without rhizobium, and for inoculation method was seed inoculation with water absorbent > seed pelleting & inoculation > seed inoculation with water > dip root at 3-leaf stage. The field experiment showed that inoculation with NM353 with seed inoculation via water absorbent method produced significant increase in yield of intercropped faba bean and maize by 79.7% and 42.8%. The intercropping system with G254 and NM353 rhizobium showed obvious yield advantage, the land equivalent ratio was >1.5. Also nitrogen content of faba bean and maize was highest among different treatments. In addition, the number of nodules, nodule biomass and nitrogen derived from air (Ndfa) and percent Ndfa (%Ndfa) were all greater in the newly-established system compared to non-inoculated faba beans. Particularly, %Ndfa of faba bean inoculated with NM353 was respectively 19.1% and 11.1% higher than that inoculated with CCBAU at peak flowering and pod-filling stages, and both had significant differences. The differences in Ndfa of faba bean were significant between rhizobium inoculation NM353 and CCBAU at each growth stage. Relatively, the difference between NM353 inoculation and the other strains was more significant for either%Ndfa or Ndfa. The inoculation with water absorbent method showed best inoculation effect with respect to nodules number, nodule biomass, %Ndfa and Ndfa. Thus an efficient cropping system was successfully set up for nitrogen fixation. The maize/faba bean-rhizobium intercropping system based on seed inoculated with Rhizobium NM353 was the most sustainable development model for rational development and utilization of the low-fertility soil.

Yield-increase effect of film-mulching and planting pattern on dryland spring maize

YAN Xudong, WANG Xiuling, XU Yupeng, WANG Weiwei, XIAO Yu, LIU Zhenmin, HUANG Sufang, YUE Mingqiang

2018, 26(1): 75-82. doi: 10.13930/j.cnki.cjea.170236

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Abstract:
Film mulching is the main mode of cultivation of spring maize in drylands. However, few studies have been conducted on the water use, root development and anti-collapse mechanisms of dry spring maize under different mulching conditions. A field research was carried out in 2013-2015 at Qianying Experimental Station of Cangzhou Academy of Agriculture and Forestry Sciences. Spring maize (Zhengdan 958) was grown for 3 years under five film-mulching and planting patterns, which were flat planting without film mulching (CK), flat film mulching and sowing under film (FC-SUF), flat film mulching and film skirting sowing (FC-FSS), film mulching on ridge and sowing under film (RC-SUF), and film mulching on ridge and film skirting sowing (RC-FSS). Yield, yield components, soil moisture, roots and lodging resistance of spring maize were investigated at different growth stages. The results showed that yields of maize under RC-FSS, RC-SUF, FC-FSS and FC-SUF increased respectively by 24.97%, 17.75%, 11.69% and 17.75% over that of CK, with RC-FSS having the highest yield. Water use efficiency (WUE) under RC-FSS increased by 26.27% compared to CK. In the 0-20 cm soil layer, soil water content was increased by 30.44%-47.66% (P < 0.01) under RC-FSS compared with CK. Spring maize under RC-FSS had the maximum lodging resistance (29.4 N), which was significantly higher than that of CK (P < 0.05). Film mulching increased soil temperature in the 0-10 cm soil layer to 0.3-2.3℃, and RC-SUF had the maximum soil temperature. RC-FSS had greater root diameter and dry weight of spring maize than RC-SUF, FC-SUF and CK (P < 0.05). This study indicated that film mulching on ridge and film skirting sowing increased or maintained yield of spring maize by increasing rainwater storage and soil moisture conservation, root growth promotion and lodging resistance. It implied that it was possible to extensively apply film mulching in the coastal plain areas with drought and little rainfall in spring.

Effects of different mulching materials on soil and near-surface environment and of apple orchard tree growth

YIN Xiaoning, LIU Xinglu, DONG Tie, NIU Junqiang, SUN Wentai, MA Ming

2018, 26(1): 83-95. doi: 10.13930/j.cnki.cjea.170586

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Abstract:
Apple is one of the top four fruits in the world and Chinese apple area and output are all the highest. Longdong, the Loess Plateau lying in East Gansu Province, is the largest apple cultivation region in China, with apple cultivated area and yield accounting respectively for 11.11% and 8.75% of the country (Gansu Rural Year book 2015). Apple is a major industry towards the alleviation of local poverty and enrichment of the local people. While drought is one of the main limiting factors of apple production under rainfed conditions, and mulching is an important method for improving the yield of apple. A field experiment was designed to find a suitable measure of soil moisture conservation in apple orchards in Longdong. In a 19-year-old 'Nagafu No.2' apple orchard, wheat straw mulching (WM), river sand mulching (SM), black plastic film mulching (FM) and clean tillage (CK) were applied to study effects of mulching matrieals on the apple orchard environment and tree development for the period from November 2010 to November 2013. Results showed that from April to June, average soil moisture content in the 0-100 cm soil layers of three mulching treatments was significantly (P < 0.01) higher than that of CK. Also the order of soil moisture content under treatments was WM > SM > FM > CK. In the third year, soil water consumptions in the 0-500 cm soil layer under WM and SM treatments were significantly (P < 0.01) lower than that of CK during the period from flower bud expansion stage to end of leaf canopy development stage, while significantly (P < 0.05) higher than that of CK for the period from end of leaf canopy development stage to maturity stage. However, total soil water consumptions of the two treatments were slightly lower than that of CK. Soil water consumption under FM treatment was significantly (P < 0.01) higher than that under CK before and after leaf canopy development. Treatment WM reduced soil temperature in the 5-25 cm soil layer during the period from March to August, increased soil temperature from September to November, but significantly (P < 0.05) decreased average daily soil temperature amplitude in the 5-25 cm soil layer, compared with CK. The near-surface temperature decreased while relative humidity increased under WM treatment compared with CK. Treatment SM had a slight effect on soil temperature, but obviously increased near-surface temperature and decreased relative humidity. The soil temperature and daily amplitude of FM treatment from March to November were always higher than those of CK, and the near-surface temperature and relative humidity were close to CK. Three mulching treatments had no obvious effect on phenological period of apple. On the whole, the order of the contents of nutrients in the 0-60 cm soil layer was WM > CK > FM > SM. The increase in almost all forms of nutrient was highest under WM treatment with the years. However, organic matter, alkaline hydrolytic N and total N in the 0-60 cm soil layer under SM treatment and in the 0-20 cm soil layer under FM treatment decreased obviously with the years. Correspondingly, total salt content (including in the 0-20 cm soil layer under WM treatment) was significantly (P < 0.01) lower than that of CK. All the mulching treatments enhanced apple tree growth, but had little effect on shoot ratio. These mulching treatments also increased single fruit weight and yield, which were significantly (P < 0.05) higher under WM treatment than under CK. Water use efficiency of WM was significantly (P < 0.01) higher than those of other treatments, and the order was WM > SM > CK > FM. The results indicated that wheat straw mulching was better for apple orchard cultivation under rainfed conditions in Longdong. The implementation of river sand mulching and black plastic film mulching should be combined with applications of organic fertilizer and other nutrients The dominant single film mulching measure in the region needed to be further improved.

Effect of nitrogen application on soil nitrogen absorption and transformation under supplementary irrigation of peanut

HU Jiaqi, XIA Guimin, ZHANG Yan, ZHANG Bailun, CHI Daocai

2018, 26(1): 96-105. doi: 10.13930/j.cnki.cjea.170523

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Abstract:
Rainfed agriculture is a mode of critical production which relies on natural rainfall in arid and semiarid regions. However, it causes crop yield instability due to frequent insufficient water supply at key growth stages of crops. Thus supplemental irrigation based on soil moisture has been widely adopted as an alternative water-saving irrigation method. To determine the effects of different nitrogen (N) application rates on nitrogen absorption and distribution, yield of peanut and soil nitrate accumulation under rainfed or supplementary irrigation conditions, a split plot experiment was conducted using the 'Baisha 1016' peanut variety with different N and irrigation managements in semiarid region of West Liaoning Province. The aim of the study was to explore suitable water and N managements and provide support for "modulate N with water" in peanut cultivation in semiarid regions. The irrigation treatments included W0 (rainfed condition) and W1 (supplemental irrigation based on soil moisture with the lower limit of soil water content of 55% of field capacity). The N treatments included N0[no N], N1[40 kg(N)·hm^-2], N2[60 kg(N)·hm^-2] and N3[80 kg(N)·hm^-2]. The results indicated that biomass and plant N uptake were highest under W1N2 treatment (supplemental irrigation at N application rate of 60 kg·hm^-2) among all treatments at maturity stage of peanut. The yield and nitrogen accumulation of peanut increased with increasing nitrogen, but decreased at N3 dose. N application rate, irrigation mode and their interactions significantly affected yield, water use efficiency (WUE), N use efficiency (NUE)[including N agronomic efficiency (NAE), grain N recovery efficiency (GRE) and apparent N recovery efficiency (NRE), and N harvest index (NHI)]. Total plant pod N accumulation greatly increased due to the optimal distribution of N nutrient in peanut, and accelerated N transfer from leaf to kernel under W1 treatment. This created beneficial effects on increasing total plant pod N accumulation, peanut harvest index, agronomic N efficiency and yield. Compared with W0, W1 increased peanut NHI, NAE and NRE by 2.13%, 78.57% and 25.90%, respectively. Soil nitrate content was highest in the 0-20 cm soil layer after peanut harvest, but decreased with increasing soil depth. The accumulation of soil nitrate N at the 0-60 cm soil depth increased with increasing N application rate. However, supplementary irrigation accelerated the leaching loss of soil nitrate N. It was concluded that W1N2 treatment had the highest yield (6 485.03 kg·hm^-2), WUE (2.02 kg·m^-3) and irrigation WUE (10.21 kg·m^-3). It was therefore recommended as the best combination for water and N to improve peanut yield under drip irrigation with plastic film mulching in semi-arid regions in Western Liaoning Province.

Combined effect of simulated precipitation and nitrogen deposition on photo-synthetic physiology of Haloxylon ammodendron in southern margin of Junggar Basin, China

ZHANG Wei, ZHAO Wenqin, XIE Shuangquan, ZHANG Li, LYU Xinhua, HE Yaling

2018, 26(1): 106-115. doi: 10.13930/j.cnki.cjea.170529

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Abstract:
Precipitation and nitrogen deposition are two of the most investigated factors of global climate change which also are the controlling factors of desert ecosystems. This study examined the combined effects of precipitation and nitrogen deposition on arid ecosystems in order to provide insight into the responses of ecosystems to global climate change. We selected plantation of Haloxylon ammodendron in the southern margin of Junggar Basin. Two precipitation conditions[natural precipitation (W₀) and 30% increased precipitation (W₁)] and three levels of nitrogen depositions[natural nitrogen deposition (N₀), 30 kg(N)·hm^-2·a^-1 (N₁) and 60 kg(N)·hm^-2·a^-1 (N₂) increased natural nitrogen deposition] were randomly added to simulate nitrogen deposition and precipitation for two years to explored the effects of precipitation, nitrogen deposition and the combined effects on diurnal change in photosynthetic and physio-ecological traits of H. ammodendron. The results showed that precipitation, nitrogen deposition and the combined effects had direct significant correlation with diurnal change in net photosynthetic rate of H. ammodendron. Based on the variation in net photosynthetic rate, intercellular CO₂ concentration and stomatal limitation of H. ammodendron, "midday depression" of photosynthesis was mainly caused by non-stomatal factors. Moreover, with increased nitrogen deposition, there were decreasing physiological indexes (MDA content, POD activity, CAT activity, SOD activity, soluble protein content and soluble sugar content) under W₀ precipitation condition. However, proline content initially decreased before eventually increasing. There were initial increases followed by decreases in physiological indexes (MDA content, POD activity, CAT activity, SOD activity, soluble protein content, proline content and soluble sugar content) under W₁ precipitation condition. With the exception of W₁N₁, proline content was lower under nitrogen deposition increase treatments than under the natural deposition treatment. Also MDA content, antioxidant enzymes activities, soluble protein content and soluble sugar content of H. ammodendron were also significantly lower under the other water/nitrogen treatments than under the control regimes. The results from the comprehensive analysis indicated that precipitation, nitrogen deposition and the combined effects benefited the growth of H. ammodendron, but the strength of the combined effect depended on the ratio between the nitrogen deposition and precipitation.

Fine root distribution in mixed Robinia pseudoacacia plantations in saline soils of the Yellow River Delta

BAI Shihong, DING Xinjing, MA Fengyun, LI Shusheng, JING Ruyan, HUANG Yali

2018, 26(1): 116-124. doi: 10.13930/j.cnki.cjea.171037

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Abstract:
To determine the distribution of fine roots of Robinia pseudoacacia mixed forests and pure forest in saline-alkali soils of the Yellow River Delta, fine root distributions in Fraxinus velutina and Robinia pseudoacacia mixed forest, Ailanthus altissima and Robinia pseudoacacia mixed forest and Robinia pseudoacacia pure forest were sampled with a soil column method. The vertical distributions of fine roots in different forest stands were analyzed for the distributions of fine root biomass density, fine root surface area density, volume density, root length density and other root parameters. The aim of the study was to clarify differences of roots distribution of different forests and their relationship with soil properties and to provide references for the vegetation recovery and tree species selection in saline soils of the Yellow River Delta. The results showed that fine root biomass, surface area, volume and root length of F. velutina and R. pseudoacacia mixed forest were significantly higher than those of A. altissima and R. pseudoacacia mixed forest and R. pseudoacacia plantation. About 95.77% of fine root biomass was distributed in the 0-60 cm soil layer for F. velutina and R. pseudoacacia mixed forest, 85.37% in the 0-40 cm soil layer for A. altissima and R. pseudoacacia mixed forest and 66.38% in the 0-40 cm soil layer for R. pseudoacacia pure forest. Although surface aggregation of fine roots was conducive to reducing the harmful effects of saline-alkaline conditions on the root, fine roots of R. pseudoacacia pure forest were more uniformly distributed in the soil. F. velutina and R. pseudoacacia mixed forest had the highest total fine root biomass (91.56 g in 2 500 cm² of soil), significantly higher than those of other trees stands. Fine root surface area, length and volume densities of F. velutina and R. pseudoacacia mixed forest were significantly higher than that of R. pseudoacacia pure forest. Fine root tips of F. velutina and R. pseudoacacia mixed forest and A. altissima and R. pseudoacacia mixed forest were respectively 2.34 and 1.23 times that of R. pseudoacacia pure forest. Root forks of F. velutina and R. pseudoacacia mixed forest and A. altissima and R. pseudoacacia mixed forest were respectively 6.15 and 1.66 times that of R. pseudoacacia pure forest. There was a significant positive correlation between stand fine root biomass with soil available phosphorus and soil available potassium contents. The correlation between fine root biomass with available nitrogen and organic matter content of F. velutina and R. pseudoacacia mixed forest was also very significant and positive. The research showed that some trees mixed patterns increased fine root biomass distribution and the ability of roots to absorb soil nutrient. This suggested that proper mixing patterns could increase the adaptability of tree plantations.

Optimal arrangement of milk vetch plantation based on land suitability and carbon sequestration in croplands:A case study of Pucheng County, Fujian Province

CAO Mengjin, ZHOU Biqing, ZHANG Liming, QIU Longxia, CHEN Rong, XING Shihe

2018, 26(1): 125-135. doi: 10.13930/j.cnki.cjea.170751

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Abstract:
Soil carbon sequestration is an important way to reduce greenhouse gas emissions. Milk vetch and other green manures importantly impact annual variations of CO₂ concentration in the atmosphere by promoting soil organic carbon accumulation and improving cropland soil fertility. However, research on the optimal arrangement of milk vetch plantation had to-date been hardly integrated with the suitability croplands for milk vetch plantation and realistic need for soil carbon sequestration. This study aimed to arrange milk vetch in the most suitable areas and fix as much CO₂ as possible. Thus the suitability of milk vetch plantations in croplands was evaluated by analyzing soil organic carbon density (SOCD) in croplands based on the 1:50 000 scale database of land use/soil pattern in Pucheng County, Fujian Province. The optimal arrangement of milk vetch plantations in Pucheng was done using an integrative method in GIS environment. Then the modificatory weighted index sum method and dynamic clustering analysis were used for both land suitability and SOCD by dividing the index based on the principle of land suitability for milk vetch plantation and carbon sequestration needs of croplands. The priority, sub-priority and general plantation areas of milk vetch in Pucheng were optimally arranged based on the principles of preferential arrangement of croplands with low topsoil SOCD and high suitability for milk vetch growth. The results showed that 81.82% of the croplands in the study area had various suitability of milk vetch plantation. If milk vetch was planted in all the cultivated lands in the study area, the annual total yield of fresh milk vetch and application rate of green manure were 657 056.65 t and 27.75 t·hm^-2, respectively; the annual carbon sequestration and the cultivated land area for which milk vetch pro-vided organic carbon sources would be 29 900.74 t and 23 677.72 hm², respectively. The range of SOCD in the study area was 2.50-5.74 kg·m^-2, differing sharply in space. On the basis of total cropland in Pucheng County, optimal area arrangement for milk vetch plantation was 59.72%, of which priority and sub-priority regions dominantly accounted for 25.72% and 50.34%, respectively. Priority region was mainly distributed in the basin area, sub-priority region distributed in the 200-400 m altitude range with gentle slope terraces, while general region was located in 250-800 m altitude range on slope terraces. The towns (including Liantang, Shuibei, Gulou, Yongxing and Zhongxin), which most needed soil carbon sequestration, were planned as the key developing areas. Then towns (e.g., Fuling, Xianyang, Shipi and Jiumu) were planned as the reserve areas for milk vetch plantation. The study provided the guide for the efficient planting and utilization of milk vetch. This showed the need to increase scientific implementation of soil organic matter programs and the continuous improvement of farmland quality by preferentially selecting suitable areas for milk vetch planting based on land suitability and carbon sequestration needs of croplands.

Distribution of nitrogen and its stable isotope from a small agricultural catchment in the subtropics

ZHAO Qiang, QIN Xiaobo, LYU Chengwen, LI Yu'e, WU Hongbao, LIAO Yulin, LU Yanhong

2018, 26(1): 136-145. doi: 10.13930/j.cnki.cjea.170539

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Abstract:
The Tuojia River basin, a typical agricultural catchment in the subtropics, was investigated in this study to clarify the spatial and temporal distribution characteristics of nitrogen and the related stable isotopes in water system of the catchment. The environmental factors influencing nitrogen distribution and the sources of nitrate nitrogen and sediment organic matter nitrogen were also determined. The concentrations of NH₄⁺-N and NO₃^--N in surface water were analyzed in a continuous monitoring experiment. At the same time, the characteristics of δ¹⁵N-NO₃^- in water and of δ¹⁵N-Org in sediments were determined. Results showed that the concentration of NO₃^--N was significantly higher than that of NH₄⁺-N in the river, with respective mean values of 1.62 mg·L^-1 and 0.90 mg·L^-1. Higher values occurred in June, August and winter periods. NH₄⁺-N concentrations in urban and farmland regions were significantly different (P < 0.05) from other areas and obviously higher than that in other water bodies. The concentrations of NO₃^--N in urban, farmland and forest areas were higher than in other regions, with lower values in reservoir areas. The order of seasonal variations in NH₄⁺-N concentration in mainstream and tributary flows was winter > spring > summer > autumn, while that of NO₃^--N concentration was winter > summer > autumn > spring in mainstream, and autumn > winter > summer > spring in tributary flows. The concentrations of NO₃^--N of mainstream and tributary flows were high but similar, and NH₄⁺-N concentration in tributary flow was higher than that in mainstream flow. At source and estuary, NO₃^--N concentration was higher than NH₄⁺-N concentration. Also, nitrogen concentration of at source was lower than that in estuaries. The distributions of δ¹⁵N values (δ¹⁵N-NO₃^-) in the river and δ¹⁵N in sediment organic matters (δ¹⁵N-Org) were respectively -19.87‰ to 8.11‰ and -0.69‰ to 6.51‰. While the highest value of δ¹⁵N-NO₃^- was in the reach Ⅲ, the lowest was in the reach Ⅳ. The difference in δ¹⁵N-NO₃^- among different reaches was small in November, but was obvious in January and February. While the highest value of δ¹⁵N-Org in river sediment was also in the reach, the lowest was in the reach Ⅰ. The variation trend in δ¹⁵N-Org in the reach Ⅲ and reach Ⅳ was consistent with change in research time. However, the lowest δ¹⁵N-Org was in January in the reach Ⅰ and Ⅱ. The research indicated that there was nitrogen pollution in Tuojia River basin, and exogenous nitrogen was the priority in the region. The main environmental factors that influenced water pollution in the region included domestic sewage, industrial wastewater, farmland nitrogen and livestock/poultry waste. In addition, the sources of nitrogen in water bodies and sediments were mainly soil organic matter, synthetic fertilizers and terrestrial organic matter. The source of nitrogen in river systems was consistent with the identified environmental factors that caused nitrogen pollution. The study of the distributions and sources of nitrogen in the basin provided scientific basis for controlling nitrogen loss in the catchment, guiding agricultural production and improving water environment in the study area.

Key issues of economic compensation system for cultivated land protection in main grain-producing areas based on a survey of 473 farmers

SUN Jingjing, ZHAO Kai, NIU Yingying

2018, 26(1): 146-155. doi: 10.13930/j.cnki.cjea.170315

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Abstract:
Economic compensation for cultivated land protection is an important measure for the implementation of farmland protection in the new period. In order to scientifically and rationally build economic compensation system for cultivated land protection, this paper analyzed the key issues of constructing cultivated land protection economic compensation system in main grain-producing areas. From farmer-willingness perspective, a questionnaire survey was conducted in Hua County of Henan Province, one of the major grain-producing counties, and the data statistically analyzed. The survey built data on the necessity for construction, compensation basis, compensation period, compensation fund assignment, acceptance and payment subjects, capital management subject, etc. Results suggested that:1) Farmers' cognition of cultivated land protection was high. 2) For constructing economic compensation mechanisms for cultivated land protection, farmers' cognition was low. However, they thought that economic compensation for cultivated land protection was very necessary. 3) In terms of compensation standard, high, medium and low compensation standards were respectively 5 446.43 ¥·hm^-2·a^-1, 4 910.71 ¥·hm^-2·a^-1 and 4 481.71 ¥·hm^-2·a^-1. The average compensation standard was 5 209.92 ¥·hm^-2·a^-1. 4) Compensation funds collected by central and local governments were completely distributed to farmers annually by using farmers' individual accounts. The main body for the payment and management was the central government. 5) For recommendations, there were needs of the establishment and improvement of active economic compensation system for cultivated land protection. Actual economic compensation standard for cultivated land protection improvement could be conducted by increasing farmers' subsidy for cultivated land protection behavior. It was necessary to set up management organization of economic compensation system of cultivated land protection in order to strengthen raising, using and managing funds for economic compensation of cultivated land protection. Finally, the publicity of cultivated land protection also should be strengthened.

Psychological cognition of pollution prevention of family-oriented scale pig breeders and environmental regulation influence effects

LIN Limei, LIU Zhenbin, DU Yanqiang, SU Shipeng, ZHENG Yifang

2018, 26(1): 156-166. doi: 10.13930/j.cnki.cjea.170828

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Abstract:
Large-scale rearing of pigs, with family members as the main labor force, is an important mode of pig production in China. The characteristics of pollution caused by this breeding model are dispersion, publicity and difficulty in locating polluters, all of which collectively weaken the effect of existing policies and regulations of pollution control. Interestingly, however, current policies and regulations target large-scale pig farming done at company level and pig breeding communities in the country, while pig farming at family level is left largely unrestrained. Conversely, the pollution caused by the mostly unchecked family-oriented pig farming has become a challenge to sustainable rural development. This paper aimed to illustrate the factors responsible for pollution prevention behavior of farmers and to provide effective recommendations to the government to better control pollution from family-oriented pig farming. In this paper, the pollution prevention and control behavior of pig breeders were divided into two categories-harmless treatment and resource utilization behavior. The research utilized a sample of 406 households engaged in pig rearing in Fujian Province, China. An empirical study was conducted to explain how farmer psychological cognition impacted pollution prevention and control behavior using Structural Equation Model. The moderating effect of environmental regulation on respondent psychological cognition and pollution control behavior was examined using Multi-Level Regression Model. The results showed that respondent pollution prevention and control behavior was positively impacted by individual psychological cognition, moderated by environmental regulations. The decisions of pollution prevention and control behaviors of farmers were due to the cognitions of responsibility, ecological rationality, and self-assessment of own pollution control ability. The decisions were also referenced from the actions of other farmers, government regulation and from non-farmer groups, and it was also a rational choice to avoid risks. Incentive and guidance measures worked hand in hand with restrictive environmental regulation in the sense that restrictive regulatory measures had a more significant effect on harmless treatment behaviors. The incentive regulation had a more important effect on resource utilization behavior. Then guidance regulation had significant regulation effect on both harmless treatment and resource utilization behaviors. To promote pollution prevention and control of family-oriented scale pig farming, this paper advised the strengthening of the application of market incentives regulation and village social capital to regulate farmer pollution prevention behavior. It was necessary for pollution control to give a full consideration to farmer dependence on rear pigs and behavior control ability. It was also advanced to guide farmers giving up pig farming in a reasonable way through strengthening industry transfer support and using warning and punishment measures.

2018 Vol. 26, No. 1