中国生态农业学报(中英文)

Variation trend and response relationship of temperature, precipitation and runoff in Baiyangdian Lake Basin

GAO Yanchun, WANG Jinfeng, FENG Zhiming

2017, 25(4): 467-477. doi: 10.13930/j.cnki.cjea.160784

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Abstract:
As the largest freshwater lake in the North China Plain, Baiyangdian Lake is a key hydro-confluence that is critical for flood prevention, sedimentation mitigation, irrigation, water supply and maintenance of ecological balance of the area. Since the 1960s, surface runoff in Baiyangdian Basin has continuously dropped, water quantity greatly reduced and lake-drying frequency increased due to the impact of climate change and human activities. The decreasing water quantity has reduced ecological function of the lake, further affecting socio-economic development and ecological security in the region. Using observed daily temperature and precipitation data at 7 meteorological stations along with monthly runoff data from 3 typical hydrological stations for the period 1957-2012, the change characteristics in temperature, precipitation and runoff in the Baiyangdian Lake Basin were analyzed. In this study, the cumulative anomaly method, Mann-Kendall test and Morlet wavelet analysis method were used to determine the trends and abrupt changes in mean annual temperature, precipitation and runoff. The purpose of this study was to develop data support and reference base for improving ecological environment and reasonable utilization of water resources in the area. The results showed that the climate in the study area had a significant warming trend with an abrupt increase of temperature since 1988. Especially, the increase of temperature in both winter and summer contributed more to temperatures rising. Annual precipitation showed a decreasing trend with obvious fluctuation. The decrease in summer precipitation (1.72 mm·a^-1) was higher than that in the other seasons. Increasing temperature along with decreasing precipitation were the dominant trends, further aggravating dry and hot climatic conditions and lake-drying in the region. There was an obvious decreasing trend in runoff due to the effect of temperature and precipitation. There was a negative correlation between runoff and temperature and a positive correlation between runoff and precipitation at annual scale. At seasonal scale, runoff was positively correlated with temperature and precipitation. Summer runoff in Fuping, Daomaguan and Zijingguan hydrological stations decreased by 0.85 m³·s^-1·a^-1, 0.72 m³·s^-1·a^-1 and 0.66 m³·s^-1·a^-1, respectively. The intervals of change in mean annual temperature, precipitation and runoff were obvious. Also the fluctuations in runoff and precipitation were consistent, suggesting that the response of runoff to precipitation was more prominent. The change in runoff was not only influenced by temperature and precipitation, but also by other climatic factors, water conservancy projects, agriculture and local geological conditions. In future studies, it was needed to further analyze the effect of each factor on the runoff in order to comprehensively understand the driving factors of runoff in the basin.

Water conservation capacity of forest ecosystems in Taihang Mountain

MA Weiling, SHI Peili, ZONG Ning, ZHAO Guangshuai, CHAI Xi, GENG Shoubao

2017, 25(4): 478-489. doi: 10.13930/j.cnki.cjea.160786

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Water conservation is a comprehensive water resources regulatory function of forest ecosystems through various hydrological processes, including canopy interception, litter containment and soil retention. As a typical northern rocky mountain area, Taihang Mountain is characterized by low rainfall with uneven seasonal distribution, shallow soil, low soil water-holding capacity and fragile environment. In spite of this, Taihang Mountain is an important ecological security shelter for the water sources belt in the North China Plain. Water has become one of the key limiting factors for the protection and restoration of vegetation in the region. Therefore, comparative analysis of water conservation capacities of main forest vegetation types is needed for development of feasible measures for water conservation and sustainable water security in the region. In this paper, we selected 196 records of canopy interception, litter and soil water carrying capacity in the natural deciduous broad-leaved forest, artificial deciduous broad-leaved forest, mixed forest, natural coniferous forest, coniferous forest and shrubs in the mountain region. We integrated water storage capacity with canopy rainfall interception, litter and soil water-holding capacity and then analyze water carrying capacities of main forest vegetation types in the area. Forest integrated water conservation capacity was calculated using a water conservation function for forest ecosystems. The results showed that:1) soil non-capillary porosity had positive correlation with integrated water holding capacity of the ecosystem and the maximum soil water-holding capacity accounted for over 90% of the total water capacity of forest ecosystems in the region. It was revealed that soil layer, as the main water reservoir, was the most important layer for hydrological processes in the forests. 2) Coniferous forests such as Pinus tabuliformis and Platycladus orientalis were more suitable for regional meteorological conditions. Redistribution capacity of precipitation by coniferous forest is significantly higher than that of other forest types. 3) Low canopy density of mixed forest was beneficial to shrub growth and its litter holding was also higher than that of pure forest. 4) Although comprehensive water storage capacity of natural forest was higher than that of plantation forest, water storage capacity of P. orientalis plantation and P. tabuliformis plantation ranked inferior to that of natural forests of Robinia psendoacacia, P. orientalis and P. tabuliformis. In summary, it was important to take afforestation measures for soil erosion, long-term forest enclosure and appropriate stand density in order to fulfill the goals of ecosystem restoration and ecological reconstruction. In order to increase water conservation capacity, plantation forest with tree species such as P. tabuliformis and P. orientalis was recommended in afforestation. This study provided the basis for the evaluation of water conservation capacity of vegetation along with rational management of forest and water resources. It laid the foundation for environmental protection and disaster prevention and mitigation in Taihang Mountain.

Estimation of arable land resources potential in hilly area of Taihang Mountain based on binary Logistic regression model

GAO Hui, TAN Limei, LIU Peng, LIU Jintong, LI Xiaorong

2017, 25(4): 490-497. doi: 10.13930/j.cnki.cjea.160778

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Research on the potential of cultivated land resources in mountainous area is particularly important for the sustainable development and utilization of arable lands. Using Jingxing County of Hebei Province, a typical hilly county in Taihang Mountain, as a case study, the potential for reserved cultivated land in mountain regions was estimated. A total of 13 ecological factors influencing the potential of cultivated land resources in hilly areas were used in the analysis-5 terrain factors and 8 climate or climate-related factors. A binary Logistic regression model was built on key ecological factors to analyze the potential of arable land resources in mountain regions in the case-study area. The distribution map of potential arable land resources in Jingxing County was draw in GIS environment based on the result binary Logistic regress and the potential arable land resources in the region analyzed from the map. The key ecological factors among 13 factors that influenced arable land resources were extracted using the same binary Logistic regression model. The order of the contribution of key ecological factors was determined using the model parameter (Waldχ²). The regression coefficient (β) was used to analyze the correlation between the key ecological factors and potential arable land resources in the region. Odds ratio (OR) was use to show correlation between the changes in configuration of key ecological factors and the changes in potential arable land resources. The results showed that there were 8 key ecological factors influencing cultivated land resources in the case-study area, with the importance order of relief > elevation > slope position index > trasp > coldness index > annual average temperature > drought index > slope. Terrain factors were more important indicators than the climate-related factors in estimation of cultivated land resource potential. Among 8 key ecological factors, annual average temperature and coldness index were both negatively and positively correlated with potential arable land resources, while other 6 factors were all negatively correlated with potential arable land resources. OR calculation showed that except drought index, the one unit change of the key ecological factors caused 1 time change in cultivated land resource potential. About 60 400 hm² of land resources were available for cultivation in the Jingxing County. The analysis of SPOT5 image showed 45 600 hm² of existing cultivated land. Therefore, there were 14 800 hm² of cultivatable land reserves in the county, accounted for 32.5% of the existing cultivatable lands in the region. This suggested that there still were a lot of cultivatable land reserves in Jingxing County. The results of this study provided theory basis for the development and utilization of cultivated land reserves in Jingxing County.

Spatio-temporal variations in vegetation NPP and the driving factors in Taihang Mountain Area

LI Xiaorong, GAO Hui, HAN Lipu, LIU Jintong

2017, 25(4): 498-508. doi: 10.13930/j.cnki.cjea.160780

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Net primary productivity (NPP) is an important indicator for the condition of vegetation in a given region. Research on NPP is not only important for the management of vegetation resources, but also a key element of global change. Technological development (such as remote sensing, geographic information system and global positioning system) had created the conditions for the establishment of complex process-based NPP models. On this basis, global NPP products today that continuously release data for long periods of time (e.g., MODIS NPP data appeared) greatly enhance research on NPP of regional vegetation. The objective of this study was to analyze the spatio-temporal variations in NPP of vegetation in Taihang Mountain Area for the period 2000-2014 using MODIS NPP data. At the same time, the study investigated the effects of climatic factors (e.g., temperature and precipitation) and of human factors (e.g., farming) on the change in NPP of vegetation in the region. Also trend analysis, correlation coefficient and zonal statistics were used in the study to analyze the various dataset (e.g., LUCC, temperature, precipitation and DEM). Results showed that the average NPP values of the study area was 284.0 g (C)·m^-2·a^-1, while those of farmland, forest and grassland were 302.5 g (C)·m^-2·a^-1, 258.1 g (C)·m^-2·a^-1 and 286.5 g (C)·m^-2·a^-1, respectively. Geographical location, topography, development history and human management influenced the distribution of the NPP of vegetation in the study area. Poor geographical environment was the main reason for the small NPP of forest vegetation in the region. The NPP of vegetation generally showed an upward trend, but was not significant for most of study area. About 16.17% area had significantly or extremely significantly increased vegetation NPP, which was mainly in the west of study area. In another 0.88% area, NPP significantly or extremely significantly dropped. The order of the NPP change rate of different vegetation types was-grassland > farmland > forest. Grassland vegetation was more effective for environmental rehabilitation because it had a better adaptability to the local conditions. Based on calculated regional averages, the vegetation NPP was significantly positively correlated with precipitation (P < 0.05), but negatively correlated with temperature (P>0.05). About 23.82% of the study area had a significantly or extremely significantly positive correlation between NPP of vegetation and precipitation, which mainly distributed in the northern section of Taihang Mountain. No significantly negative correlation was observed. Furthermore, about 8.42% of the study area had a significantly or extremely significantly negative correlation between vegetation NPP and temperature, and this was mainly in the west side of Taihang Mountain. In another 0.81% area, the vegetation NPP was significantly or extremely significantly positively correlated with temperature, which was mainly distributed in the extreme north of the study area. Also the rate of NPP change and the correlation coefficient between NPP and climatic factors was positively correlated with altitude and slope gradients-both relatively smaller at low altitude and small slope, where human activity intensity was relatively higher. The area with significantly or extremely significantly reduced vegetation NPP was across the study area, especially around construction lands, which was not as a result of climatic factors. It was therefore suggested that while climatic factors generally enhanced vegetation NPP, human factors mainly inhibited vegetation NPP in the study area during the study period.

NDVI variation tendency under different slopes in Taihang Mountain

LI Wei, TAN Minghong

2017, 25(4): 509-519. doi: 10.13930/j.cnki.cjea.160781

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Slopes in mountain areas are critical for the management of soil erosion and vegetation growth-a key determinant factor of site conditions of vegetation. Analysis of the variation tendency of NDVI (normal difference vegetation index) at different slope gradients in Taihang Mountain helps not only to understand the response of vegetation to slope gradients under long-term adaptation, but also to deepen the understanding of the variation mechanism of vegetation. Using the 250 m×250 m resolution MODIS data derived from NASA Terra Satellite, the 90 m×90 m resolution DEM data from SRTMDEM, pixel-scale trend analysis and slope-related regression analysis, this study investigated the changes in vegetation conditions in Taihang Mountain for the period 2000-2015. As the most important indicator, average NDVI in growing season was used for vegetation condition. After the selection of about 1 000 typical samples in the study area, the relationship between changes in the greenness of vegetation and slope gradient was explored using regression analysis. Meanwhile, land use transition matrixes were used to explore the transfer and direction of the acreage of land between different land use types under different slope gradients. The results showed that:1) the greenness of vegetation in Taihang Mountain improved for the study period, the vegetation-improving area accounted for 93.5% of the total study area. 2) The most obvious increase trend in NDVI was in the central and western regions (especially in central and east Shanxi Province). Also the most obvious decrease trend of NDVI was in patches of medium and lower elevations in eastern and southern Taihang Mountain, which was mainly concentrated in the eastern hilly regions adjacent to the North China Plain. 3) Average NDVI for the growing season increased with increasing slope. 4) The relationship between variation trend of NDVI (y) and slope (x) was non-linear, and the best represented by a quadratic function (y=-0.311x²+8.098x+28.027). 5) The tendency for increase in NDVI was most obvious for slope gradient within the range of 7°-15°, then for slope gradient of 15°-20°. The tendency of NDVI variation in slope range of 7°-20° was 15.8% and 29.8% higher than that in the slope > 20° and≤7°, respectively. 6) From 2000 to 2010, areas of arable land, grassland and forest land under lower (0°-7°), middle (7°-20°) and higher (> 20°) slopes decreased, and mainly transformed into construction land. However, the NDVI variation trends in the three slope ranges were all positive, and the most obvious was the middle slope area, followed by higher slope area and lower slope area. 7) The trend of NDVI variation was less affected by land use type and area, which was mainly influenced by its biochemical conditions, natural environment and human disturbance (land use intensity). Based on the above results, this paper is of great significance to rational utilization of land resources and ecological and environmental protection under different slopes of Taihang Mountain.

Nitrogen and phosphorus resorption efficiency of forests in North China

ZONG Ning, SHI Peili, GENG Shoubao, MA Weiling

2017, 25(4): 520-529. doi: 10.13930/j.cnki.cjea.160787

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Abstract:
Nutrient cycling is one of the basic functions of forest ecosystems. As two of the main nutrition elements, nitrogen and phosphorus are critical for proper metabolism and growth processes of plants. In order to reduce the dependence on external nutrient, plants can resorb nutrients from senescing leaves prior to abscission and store them into other plant tissues for reuse. Resorption efficiency, defined as the percent nutrient reduction between live and senescent leaves, is used to quantify the resorption capacity of a plant. Nutrient resorption is a key process of plant nutrient utilization strategy. Through nutrient resorption, plants can reduce nutrient loss from the ecosystem and lower the dependence on the environment. This is crucial for the stability of plant population and community, and for ecosystem nutrient cycling. Based on published papers on forests in mountain regions of North China (including the Loess Plateau, Taihang Mountain, North Beijing Mountain Area, etc.), the systemization of nitrogen and phosphorus contents in mature and senescent leaves of forests was conducted depending on the life forms and management methods of forests. All in all, we collected data on nitrogen and phosphorus at 13 sites in the three regions and conducted a comprehensive assessment on nutrient resorption efficiencies. We compared nitrogen and phosphorus resorption efficiencies between trees and shrubs, as well as between natural and plantation forests. In order to explore the factors regulating nutrient resorption efficiency, we also analyzed the relationships between the contents of nitrogen and phosphorus against nutrient resorption efficiency. The results showed that the ranges of nitrogen and phosphorus resorption efficiencies for forests were respectively 24.5%-71.3% and 18.1%-75.4%, with averages of 45.5% and 47.4%, both slightly lower than global average. Average nitrogen content in mature leaves of plantation forests was 21.6 g·kg^-1, significantly higher than that of natural forests (11.6 g·kg^-1). This indicated that in the process of growth of plantation forests, there could be excessive consumption of nutrients. In Taihang Mountain, nitrogen content in mature and senescent leaves and nitrogen resorption efficiency for shrubs were significantly higher than those for trees. However, phosphorus resorption efficiency was relatively lower, demonstrating that plant growth in the region was mainly limited by nitrogen supply. Comparisons among different areas showed that nitrogen and phosphorus resorption efficiencies in North Beijing Mountain Area were higher than those in the Loess Plateau and Taihang Mountain. Correlation analysis showed that both nitrogen and phosphorus resorption efficiencies were significantly correlated with nitrogen content in senescent leaves, indicating that the nitrogen content of senescent forest leaves (also called nutrient resorption proficiency) in North China was the main limiting factor of nitrogen and phosphorus resorption efficiencies. Based on the comparison of nutrient resorption efficiencies of different vegetation species, nutrient resorption efficiencies were greater for conifer forests than that for broad-leaved species. This suggested that in nutrient-barren soils in mountain terrains, nutrient resorption in conifer forests was more efficient, and conifer trees were probably more adaptable to such barren soil environment. In the process of development of artificial plantations in mountain regions, it was recommended to consider high nutrient use efficiency of conifer forests.

Estimation of grassland biomass using MODIS data and plant community characteristics

YAO Xingcheng, QU Tiantian, CHANG Wenjing, YIN Jun, LI Yongjin, SUN Zhenzhong, ZENG Hui

2017, 25(4): 530-541. doi: 10.13930/j.cnki.cjea.160931

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In the context of global climate change, the accurate estimation of grassland biomass is critical for terrestrial carbon cycling research. In China, most studies in this area have focused on grasslands in North China over the past decades. Only a few studies have estimated grassland biomass in South China, mainly due to difficulties in spatial complexity of plant species in the region. Therefore, it is necessary to develop a model for the estimation of grassland biomass in South China in order to analyze the spatial distribution of this vegetation type. In this study, we first developed a model for the estimation of aboveground grassland biomass (AGB) in Yunnan Province using field sample and NDVI (normalized difference vegetation index) data (2012-2014), derived from MODIS sensor. The derived grassland characteristics (height and coverage) were then inputted into the model to improve the estimation accuracy. With the improved model, we used remote sensing and GIS platforms to map the spatial pattern of AGB in Yunnan Province. Finally, we carried out statistical analysis of AGB of grassland in a district in Yunnan Province and calculated the average density of AGB in multiple types of grassland. The results indicated that:1) the model for the estimation of AGB of grassland was improved by the use of field data on plant community. Thus the goodness-of-fit (R²) of the model increased by 0.289 and the estimation accuracy of the model also increased (35.0%-43.7%) significantly. 2) During 2012-2014, annual total AGB in the study area was 1.03×107-1.41×107 tons, with an average value of 1.22×107 tons that accounted for 4.1% of total AGB in China. The results suggested that the area of grasslands in South China is not negligible. The density of AGB of grassland in Yunnan was highest in the eastern and southern regions of the province. 3) The density of AGB of grassland in the districts of Yunnan was 1 130.12-2 116.03 kg·hm^-2. Grasslands with high AGB densities were in southern and southwestern areas of the province, including Xishuangbanna, Dehong and Puer. Grasslands with low densities were in northwestern and eastern areas of the province, including Diqing and Qujing. Moreover, AGB density of mutiple grassland types had a clear pattern, with an increasing trend from montane meadow to tropical herbosa. The order of the AGB density increase was:montane meadow (1 071.73 kg·hm^-2) < lowland meadow (1 552.45 kg·hm^-2) < tropical shrub herbosa (1 579.80 kg·hm^-2) < warm-temperate shrub herbosa (1 588.12 kg·hm^-2) < warm-temperate herbosa (1 771.02 kg·hm^-2) < tropical herbosa (2 004.37 kg·hm^-2). In the study, a remotely sensed vegetation index was first combined with field data on plant community. Using this approach, the accuracy of the results increased with 24.9%, compared with the traditional approach which relies only on remote sensing data. Thus in order to improve the accuracy of AGB estimation for grasslands at a large scale, it was recommended that future studies attempt to incorporate grassland height derived from Light Detection and Ranging equipment (LiDAR) data or optical stereo images.

Characteristics of readily oxidizable organic carbon and soil organic carbon pool under long-term fertilization in cinnamon soils

SHI Kangjie, ZHOU Huaiping, YANG Zhenxing, XIE Wenyan, CHENG Man

2017, 25(4): 542-552. doi: 10.13930/j.cnki.cjea.160688

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The effects of 24 years of long-term fertilization on total organic carbon (TOC), total organic carbon storage (TOCs), net carbon sequestration efficiency (NCSE) and carbon pool management index (CPMI) of cinnamon soils were analyzed in order to provide theoretical basis for the evaluation of soil carbon pool change and quality, and to guide scientific application mode of fertilizers in cinnamon soils. Using data from long-term experiment on soil fertility and fertilizer use history, TOC and ROOC (readily oxidizable organic carbon) contents were analyzed and the relative indexes for TOCS, NCSE and CPMI were calculated for 9 different treatment conditions. The treatments included Group A[no fertilization treatment (N₀P₀, CK)], Group B[single application of inorganic fertilizer treatments (N₁P₁, N₂P₂, N₃P₃ and N₄P₄)], Group C[mixed organic and inorganic fertilizers treatments (N₂P₁M₁, N₃P₂M₃ and N₄P₂M₂)] and Group D[single application of high amount of organic fertilizer treatment (M₆)]. Results showed that the application of medium and high organic manure (N₃P₂M₃ and N₄P₂M₂) increased the contents of TOC and ROOC in different soil layers and in different periods, but the promotion effect decreased with increasing soil depth. TOCS, NCSE and TOC had similar trends in both time and space. TOCS increased with increasing application of organic fertilizer (Group C, Group D), with 76.77% and 17.36% lower for average of Group A and Group B than that for Group C and Group D, respectively. Long-term fertilization improved net carbon fixation efficiency and the application of organic fertilizer significantly improved NCSE. NCSE decreased in the order of Group D > Group C > Group A > Group B. NCSE for Group D was 1 152.27 kg·hm^-2·a^-1, which was 2.51 times that of Group C, and 16.20 times that of Group B. Compared with CMPI before the experiment, there was no significant difference in CPMIs of Group C and Group D; while CPMIs of Group A and Group B decreased by 16.38-40.02. Also compared with control, the application of low-level inorganic fertilizer treatment (N₁P₁) and application of organic fertilizer of Group C and Group D significantly increased CPMI by 23.30-45.67. There was a significant positive correlation between CPMI and ROOC in the 0-40 cm soil layer, which implied that CPMI was a good indicator for organic carbon change. As noted, the application of high amount of organic manure or high amounts of organic and inorganic fertilizers (N₃P₂M₃ and N₄P₂M₂) significantly improved soil TOCS, NCSE and CPMI. In other words, application of high amounts of organic fertilizer increased organic carbon sequestration, decreased the application of inorganic fertilizer and enhanced better soil development and soil fertility.

Impact of sowing date on yield and water use efficiency of wheat in different precipitation years in dryland of South Shanxi

PEI Xuexia, DANG Jianyou, ZHANG Dingyi, WANG Jiao'ai, ZHANG Jing, DONG Fei

2017, 25(4): 553-562. doi: 10.13930/j.cnki.cjea.160742

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Sowing date affects individual development before winter, population quality and yield of wheat. Planting area of wheat in dryland of South Shanxi accounts for 60% total area of the province. The precipitation in the area plays an important role in ensuring agriculture production and food security in Shanxi Province. Under global warming conditions, research on proper sowing date of wheat in Shanxi Province is significant for sustainable development of agriculture. Seven years from 2008 to 2015 were divided into three kinds of precipitation year types-wet precipitation year (2012, 2014 and 2015, precipitation of 527.8-597.2 mm), normal precipitation year (2011, 2013, precipitation of 450.7-483.3 mm) and dry precipitation year (2009, 2010, precipitation of 293.4-385.4 mm), based on the average annual precipitation of Linfen in Shanxi Province in the past 54 years. Precipitation, accumulated temperature, sunshine duration during wheat growth season, as well as wheat growth duration, yield and water use efficiency (WUE) under three sowing dates (Sep. 20, 30 and Oct. 5 in 2008-2009; Sep. 22, 28, and Oct. 4 in 2009-2015) were analyzed to provide a theoretical basis and technological support for high and stable yield production of dryland wheat. The relationship between yield, yield components, WUE and meteorological factors were also analyzed by correlation, multiple regression and path analysis. Results showed that sowing dates significantly affected seedling, tillering and jointing period duration, while no significant effect was observed at booting and maturing stages. There was a significantly positive relationship between wheat growth duration and accumulated temperature. Precipitation year and precipitation distribution in wheat growth season affected wheat yield and yield components significantly. Yield in wet precipitation years were 100.0% and 135.9% higher than those in normal and dry precipitation years, respectively. For different precipitation year types, WUE of grain were wet precipitation year > dry precipitation year > normal precipitation year. WUE of grain were increased with the delay of sowing date in wet and dry precipitation years, but was increased when sowed before Sep. 28 and then decreased in the normal precipitation year. From jointing to heading stage, wheat yield was negatively related with accumulated temperature and sunshine duration, positively related with precipitation. From heading to maturing stage, it positively correlated with accumulated temperature and sunshine duration. There was a positive relationship between yield, yield components and water consumption, but no significant relationship between WUE and meteorological factors and yield components. Annual precipitation and its distribution were the key factors determining high and stable wheat yield in dryland. In wet years, Oct. 4 was a suitable sowing date, which was beneficial for coordinative yield components, high yield and WUE, and low water consumption of wheat. In normal and dry years, Sep. 28 was more suitable for higher yield and WUE of wheat.

Effect of combined application of Chinese milk vetch and nitrogen fertilizer on nitrogen uptake, utilization and dry matter accumulation in early rice

QIAN Chenchen, WANG Shubin, YANG Binjuan, HUANG Guoqin

2017, 25(4): 563-571. doi: 10.13930/j.cnki.cjea.160857

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This study evaluated the effect of combined application of Chinese milk vetch (Astragalus sinicus L.) and different levels of nitrogen (N) fertilizer on dry matter accumulation and N use efficiency of early rice in order to determinate the suitable N level under application of Chinese milk vetch. Field treatments were set with four N application levels (90 kg·hm^-2, 120 kg·hm^-2, 150 kg·hm^-2 and 180 kg·hm^-2) under 22 500 kg·hm^-2 Chinese milk vetch using the winter fallow field with general N fertilizer level (150 kg·hm^-2) as the control. In the experiment, Chinese milk vetch was planted in winter and incorporated into soil in spring before early rice transplant, while N fertilizer was applied as base fertilizer, tillering fertilizer and heading fertilizer with 5:3:2 rate. The rice plants were sampled at tillering, booting, heading, filling and maturity stages of the early rice. Dry matter weight and N content were assayed, and the relative indexes were calculated. The results showed that all N application treatments had higher dry matter accumulation than the control. Specifically, the treatments with Chinese milk vetch combined with 90 kg (N)·hm^-2 and 120 kg (N)·hm^-2 increased dry matter (9.65 t·hm^-2 and 9.97 t·hm^-2) respectively by 11.18% and 14.86% compared to the control. Dry matter accumulation increased with duration of growth and peaked twice, one at sowing-tillering stage (19.26%-24.77%) and the other at heading-filling stage (45.23%-52.75%). The combined application of Chinese milk vetch and N fertilizer supported N integration that was beneficial to rice growth. The amounts of N accumulation of early rice treated with Chinese milk vetch and N fertilizer were higher than the control, with increases of 6.95%-18.68%. Among the treatments, that of Chinese milk vetch combined with 90 kg (N)·hm^-2 had the highest production efficiency of dry matter and N harvest index, with respective increases of 3.94%-14.08% and 6.65%-14.90% over other treatments. The results indicated that combined application of Chinese milk vetch with 90 kg (N)·hm^-2 or 120 kg (N)·hm^-2 was satisfactory because they reduced N fertilizer and increased N use efficiency at the same time, which was the ideal fertilization model for the study area.

Dynamic model and characteristics analysis of dry matter production after light recovery of different soybean varieties in relay strip intercropping systems

WU Yushan, GONG Wanzhuo, YANG Wenyu, YONG Taiwen, YANG Feng, LIU Weiguo, WU Xiaoling

2017, 25(4): 572-580. doi: 10.13930/j.cnki.cjea.160928

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Maize-soybean relay strip intercropping is a widespread practice in soybean production areas in southwestern and southern China and has been the main mode of increasing total output of soybean in China. To provide theoretical basis for the selection and breeding of high yield soybean varieties for intercropping, this study used fourteen soybean varieties with different yield levels to analyze the characteristics of dry matter production after light recovery (after maize harvest) of different yield types of soybean varieties relay strip intercropped with maize. Results indicated that average grain yield of high yield soybean varieties was 1 408.17 kg·hm^-2, which was 37.45% and 57.25% higher than those of medium and low yield varieties, respectively. Dry matter accumulation of high yield soybean varieties was on an average of 32.99 g·plant^-1, which was 26.82% and 91.51% higher than those of medium and low yield varieties, respectively. Logistic equation was used to simulate the relationship between dry matter weight and days after light recovery for three types of soybean varieties (R²≥0.960). Paired t-test for independent samples showed no significant difference between the simulated and measured values. After light recovery, the rate of dry matter accumulation of three types of soybean varieties increased before declining. The order of maximum rate of dry matter accumulation and the mean rate of dry matter accumulation was high yield type > medium yield type > low yield type. The average time to maximum rate of dry matter accumulation after light recovery of the high yield soybean varieties was 41-42 days, while that of both medium and low types was 33-37 days. The duration, accumulation rate and accumulation amount of dry matter of gradual increase stage; the accumulation rate and amount of dry matter accumulation of both fast increase and slow increase stages of high yield soybean were significantly higher than those of other two yield types of soybean. The yield had a significantly positive correlation with the maximum dry matter accumulation rate, time reaching the maximum dry matter accumulation rate, mean dry matter accumulation rate, duration of gradual increase stage, dry matter weight of gradual increase stage, dry matter accumulation rate and weight of both fast and slow increase stages. Two years data indicated that leaf area index, light interception rate, population growth rate and leaf area duration of high yield soybean were 2.52 g·m^-2·d^-1, 0.81 g·m^-2·d^-1, 6.02 g·m^-2·d^-1 and 317.84 m²·d·m^-2, respectively, which were significantly higher than those of both medium and low yield types. Our results suggested that greater dry matter accumulation mainly occurred at gradual increase stage after light recovery for high yield soybean varieties, which was mainly attributed to the longer duration of the stage.

Effect of continuous potato monoculture on soil chemical and biological prop-erties in Yellow River Irrigation Area in central Gansu Province

LIU Xing, QIU Huizhen, ZHANG Wenming, ZHANG Chunhong, ZHU Jing, MA Xing, CHENG Wanli

2017, 25(4): 581-593. doi: 10.13930/j.cnki.cjea.160848

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Abstract:
The irrigation area along the Yellow River in central Gansu Province is an important growing region of processing potato and seed potato in China. Continuous potato monoculture (CPM) stemming from intensive cultivation has severely affected the healthy development of local potato industry. It is necessary to increase our understanding about the barrier associated with CPM. To that, a long-term field experiment was conducted, which contained 5 potato cropping treatments corresponding to continuous potato cropping for 1-5 years, with maize-potato rotation cropping as the control. In the study, we focused on how the soil chemical and biological properties changed in CPM system, and which soil variables contributed principally to the barriers of CPM. The study showed that contrary to alkaline hydrolyzable nitrogen, NH₄OAc extractable potassium and electrical conductivity, soil organic carbon content gradually decreased with increasing years of CPM. Also compared with the control, CPM significantly increased soil NaHCO₃ extractable phosphorus content. However, there were no significant changes in total nitrogen, C/N ratio and pH. Compared with the control, long-term CPM (over 3-5 years) decreased mean soil enzyme activity by 33.07%-61.78%. The activities of urease, sucrose and dehydrogenase decreased with increasing years of CPM. Long-term CPM decreased the content of soil microbial biomass carbon, while both soil basal respiration and FDA hydrolysis activity exhibited highly significant linear negative correlation with the number of year of CPM. Results of Biolog ECO assessment indicated that long-term CPM significantly decreased total activity and function diversity of soil microbes, where Shannon diversity index for long-term CPM decreased by 11.75%-13.65% compared with the control. Principal component analysis of carbon utilization profile of soil microbes showed that long-term CPM clearly changed the structure of soil microbial community compared with the control. Among the 6 groups of carbon source substrates, carbohydrates type was most sensitive to the changes in soil microbial communities in CPM system. Long-term CPM significantly decreased the relative utilization ratio of selected carbon source substrates for soil microbes, including carbohydrates, amino acids, carboxylic acids and amines. For 31 sole-carbon source substrates, the utilization pattern of soil microbes under long-term CPM was more centralized than under the control or short-term CPM. Linear models of stepwise regression analysis and path analysis confirmed that a total of 4 soil variables (soil microbial community structure, soil microbial biomass carbon, total nitrogen and dehydrogenase) significantly affected tuber yield under CPM system, and that soil microbial community structure contributed most, followed by soil microbial biomass carbon. The results of the study suggested that soil microbial variables were the main causes of the barriers of CPM system in the Yellow River Irrigation Area in central Gansu Province.

Microbial community structure in rhizosphere soils of long-term continuously cropped processing tomato based on PLFA method

KANG Yalong, SUN Wenqing, LIU Jianguo, JIANG Guiying

2017, 25(4): 594-604. doi: 10.13930/j.cnki.cjea.160844

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Abstract:
Xinjiang Uygur Autonomous Region is a major production base of processing tomato in China. In the effort to meet market demand for processing tomato, mono-cropping has been widely adopted. Unfortunately, this phenomenon has become the dominant factor limiting the stable production and yield of tomato in the region. Here, we conducted a field study to determine the impact of continuous cropping over the long-term on microbe community structure in rhizosphere soil of processing tomato using phospholipid fatty acid (PLFA) and chloroform fumigation extraction method. The mono-cropping field experiment started in 2007 at a station belonging to the College of Agriculture of Shihezi University. The processing tomato cultivar used in the experiment was 'Ligeer 87-5'. Soil samples were collected for analysis from plots with different cultivation histories (3, 5 and 7 years of continuous cropping) and a control plot that was under fallow for 3 years. The results showed that soil microbial biomass C (SMBC), soil microbial biomass N (SMBN) and soil microbial biomass entropy (qMB) significantly decreased, while soil microbial biomass C/N increased with increasing duration of continuous cropping (P < 0.05). However, soil microbial biomass P (SMBP) exhibited a different response to both continuous cropping and various growth stages. PLFA analysis indicated that continuous cropping significantly increased fungal PLFAs, whereas the reverse trend was observed for bacterial PLFAs, total PLFAs and the ratio of bacterial PLFAs to fungal PLFAs. However, actinomycetous PLFAs had no regular change with increasing duration of continuous cropping. After 7 years of continuous cropping, bacterial PLFAs and total PLFAs amount decreased by 62.9% and 50.3% (P < 0.05), respectively, but fungal PLFAs amount significantly increased by 60.2% compared with control. Based on diversity index analysis, Shannon-Wiener index, Simpson index, Brillouin index and Pielou index all initially increased and then decreased with increasing years of continuous cropping of processing tomato. Soil microbial diversity index was highest in the treatment of 3 years continuous cropping and was lowest for the treatment of 7 years continuous cropping. It was concluded that microbial community diversity and uniformity decreased with increasing of continuous cropping years in this area. Correlation analysis showed significant correlation among PLFAs of bacteria, fungi and actinomycetes, total PLFAs, soil microbial biomass and soil fertility, which indicated that soil microbial biomass was highly related with soil fertility. Therefore, soil microbial biomass could be used as an available biological index for the evaluation of soil fertility. The results suggested that years of mono-cropping had a major influence on microbial community structure and soil microbial biomass in rhizosphere soil of processing tomato, which in turn limited sustainable development of processing tomato.

The detection and monitoring of available heavy metal content in soil: A review

ZHOU Weihong, ZHANG Jingjing, ZOU Mengmeng, DU Xiaolong, ZHANG Ying, YANG Yue, LI Jianlong

2017, 25(4): 605-615. doi: 10.13930/j.cnki.cjea.160904

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Abstract:
With the rapid development of economy and society, the problem of heavy metal contamination in soil is becoming serious increasingly, which threatens the food security and human health. However, the detection method of total concentration of heavy metal in soil can not accurately reflect the actual toxicological bioavailability of heavy metal in soil. To further analyze the existing forms of heavy metal in soil and their biotoxicity, it is necessary to assess both the existing forms and the contents of heavy metal. This article described the definition of availability of heavy metal and its transfer mechanism in soil-organism system. According to related data and documents, divided the detection methods of availability of heavy metal in soil into two kinds of methods:direct methods (chemical detection methods and physical detection methods) and indirect methods (biological indicator methods). The research progress, application scope and characteristics of chemical extraction methods, diffusive gradients in thin-films (DGT), spectrum analysis methods, plant indicator method, microbial indicator method and soil animal indicator method were systematically set forth, and the major problems of existing detection methods were summarized. At last, the paper pointed out that it was urgent to ensure food security and human health by preventing soil pollution and remediation of contaminated soil based on rapid, in-situ and non-invasive detection and monitoring of forms, contents and pollution degrees of heavy metals in soil in large-area. However, it depends on developing of more accurate detection methods by understanding the mechanism of the translocation and accumulation of heavy metal in system of soil-crop-human. In addition, the in-situ stereo detection and monitoring methods combined with remote sensing (RS), geographic information system (GIS) and global positioning system (GPS) are the hot spots of the detection and monitoring of heavy metal speciation in soil in future, and with the development of hyperspectral remote sensing technology and data processing technology, this kind of detection and monitoring methods of heavy metals can meet the requirements of large area and accurate detection and monitoring of available heavy metals contents in soil.

Effect of aggregated amino acid on the form of iron oxide in paddy soils in North China

ZHA Wenwen, GUAN Lianzhu, ZHANG Guangcai, ZHANG Yun, GAO Xiaodan, CHEN Weiwei, WU Chunlong, WANG Mingda, JIANG Xuenan, PAN Linlin, ZHANG Ting, ZHAO Ya

2017, 25(4): 616-622. doi: 10.13930/j.cnki.cjea.160773

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Abstract:
The purpose of this study is to characterize the amount of iron oxide in different types of paddy soil and investigate the effect of exogenous polymeric amino acids on their forms transformation. Different types of paddy soil (brown soil, meadow soil and littoral saline soil) in North China were chosen as the research object. An incubation experiment was carried out by adding γ-poly-glutamic acid and poly aspartic acid, according to 0.05% of dry soil weight to these three paddy soils. After constant temperature and anaerobic incubation for 30 days, the content of total iron oxide (T_Fe), free iron oxide (D_Fe), amorphous iron oxide (O_Fe) and complexed iron oxide (C_Fe) were measured, and the activation and complexing degree of iron oxide were calculated in three paddy soils. Simultaneously, no addition of amino acids was set as the control. The results showed that (1) the content of free iron oxide in three typical paddy soils from high to low was:littoral saline soil > meadow soil≥brown soil; the sequence of complex iron oxide content was brown soil > littoral saline soil≥meadow soil; and the sequence of amorphous iron oxide was brown soil > littoral saline soil > meadow soil. (2) The content of amorphous iron oxide and complexed iron oxide increased by 27.72% and 32.25%, respectively, in paddy soil derived from brown soil with γ-poly-glutamic acid application compared with that of control; but there was no significant change for those adding poly aspartic acid. The content of amorphous iron oxide could be significantly increased by adding both γ-poly-glutamic acid and poly aspartate acid in paddy soil derived from meadow soil, and the complexed iron oxide increased by 136.24% and 12.00% compared with that of control, respectively. The addition of γ-poly-glutamic acid effectively increased the content of amorphous and complex iron oxide in paddy soil derived from littoral saline soil. In conclusion, no significant difference in the content of free iron oxide was observed in the three paddy soils with treatment of γ-poly-glutamic acid addition. While the addition of γ-poly-glutamic acid effectively increased the contents of amorphous and complex iron oxide, but decreased the crystallization rate of iron oxide, which is helpful to improve the content of available Fe. Furthermore, it also activated the iron oxide significantly and restrained the crystallization of iron oxide in three paddy soils. While the application of poly aspartic acid had no obvious excitation effect on complexed and amorphous iron oxide.

2017, 25(4): 623-624. doi: 10.13930/j.cnki.cjea.170182

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Abstract:

2017 Vol. 25, No. 4