The Experts below are selected from a list of 8976 Experts worldwide ranked by ideXlab platform
Mingan Shao - One of the best experts on this subject based on the ideXlab platform.
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Soil organic carbon in Deep profiles under chinese continental monsoon climate and its relations with land uses
Ecological Engineering, 2015Co-Authors: Yunqiang Wang, Mingan Shao, Chencheng Zhang, Zhipeng Liu, Junliang Zou, Jingfeng XiaoAbstract:We collected Soil samples from depths between 0 and 12-21 m at 33 sites across the Chinese Loess Plateau in order to determine the vertical distributions and storage of Soil organic carbon (SOC), as well as to test the hypothesis that SOC in Deep Soils (below 5 m) is greater under forest than under permanent cropland. The overall distributions of SOC within a profile were divided into three sub-Layers: 0-2, 2-14, and 14-21 m, with significantly different (P < 0.01) mean SOC values of 3.28 +/- 2.39, 2.07 +/- 0.79, and 1.56 +/- 0.57 g kg(-1), respectively. In the Deep Soil Layer (5-21 m), SOC storage was significantly higher (P < 0.01) under forest (47 +/- 0.43 kg m(-2)) than under cropland (38 +/- 0.44 kg m(-2)). Within the rooting zone, the factors affecting SOC variation were root length, pH and clay content; below the rooting zone, the factors were Soil water content, pH and clay content. Land use and rooting characteristics significantly affected the magnitude and vertical distribution of SOC within both shallow and Deep Layers. Therefore, changes in land use can alter SOC storage in Deep Soils, which can have important consequences for global climate change. (C)2015 Elsevier B.V. All rights reserved.
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the characteristics of Soil water cycle and water balance on steep grassland under natural and simulated rainfall conditions in the loess plateau of china
Journal of Hydrology, 2008Co-Authors: Hongsong Chen, Mingan ShaoAbstract:Summary Large-scale vegetation restoration has been helpful to prevent serious Soil erosion, but also has aggravated water scarcity and resulted in Soil desiccation below a depth of 200 cm in the Loess Plateau of China. To understand the dynamic mechanism of Soil desiccation formation is very important for sustainable development of agriculture in the Loess Plateau. Based on natural and simulated rainfall, the characteristics of Soil water cycle and water balance in the 0–400 cm Soil Layer on a steep grassland hillslope in Changwu County of Shaanxi Loess Plateau were investigated from June to November in 2002, a drought year with annual rainfall of 460 mm. It was similarly considered to represent a rainy year with annual rainfall of 850 mm under simulated rainfall conditions. The results showed that the temporal variability of water contents would decrease in the upper 0–200 cm Soil Layer with the increase in rainfall. The depth of Soil affected by rainfall infiltration was 0–200 cm in the drought year and 0–300 cm in the rainy year. During the period of water consumption under natural conditions, the Deepest Layer of Soil influenced by evapotranspiration (ET) rapidly reached a depth of 200 cm on July 21, 2002, and Soil water storage decreased by 48 mm from the whole 0–200 cm Soil Layer. However, during the same investigation period under simulated rainfall conditions, Soil water storage in the 0–400 cm Soil Layer increased by only 71 mm, although the corresponding rainfall was about 640 mm. The extra-simulated rainfall of 458 mm from May 29 to August 10 did not result in the disappearance of Soil desiccation in the 200–400 cm Deep Soil Layer. Most infiltrated rainwater retained in the top 0–200 cm Soil Layer, and it was subsequently depleted by ET in the rainy season. Because very little water moved below the 200 cm depth, there was desiccation in the Deep Soil Layer in drought and normal rainfall years.
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Soil desiccation in the loess plateau of china
Geoderma, 2008Co-Authors: Hongsong Chen, Mingan Shao, Yuyuan LiAbstract:Abstract Soil desiccation usually takes place below the depth of Soil affected by rainfall infiltration (about 1–3 m) with relatively low water content, and is one kind of particular hydrological phenomena in semi-arid and semi-humid regions of the Loess Plateau in China. This desiccation results from the excessive depletion of Deep Soil water by artificial vegetation and long-term insufficient rainwater supply, which is difficult to disappear with land use change. Due to the influence of global warming during 1950–2000, large-scale vegetation rehabilitation aggravated water scarcity and led to Soil desiccation in the Deep Soil Layer in the Loess Plateau. From southeast to northwest, Soil desiccation becomes more intensive with lower water content and bigger range in depth due to drier climate and lower water holding capacity. The range of Soil desiccation has a close relationship with root distribution of plant, and its intensity varies with the types and ages of vegetation. The climate drought, Soil properties and Soil water cycle characteristics might be the precondition for the occurrence of Soil desiccation, and artificial vegetation with improper type and exorbitant productivity could have accelerated this process in range and intensity. Soil desiccation has obviously negative effects on water cycle in Soils, greatly reduces the anti-drought capacity of plants, and heavily influences the growth and natural succession of vegetation. In order to reduce the range, intensity, and negative effects of Soil desiccation, proper types of vegetation should be selected according to rainfall and Soil water conditions, and the control of vegetation density and productivity should be considered together with Soil-water conservation measures.
Hua Zhou - One of the best experts on this subject based on the ideXlab platform.
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effects of nutrient cycling on grain yields and potassium balance
Nutrient Cycling in Agroecosystems, 2009Co-Authors: Zishao Jiang, Hua ZhouAbstract:Soybean-maize rotation is a profitable cropping system and is used under rain fed conditions in north China. Since crop yields have been reported to decrease when K fertilizers are not used, we analyzed the productivity trends, Soil-exchangeable and non-exchangeable K contents, and K balance in a continuous cropping experiment conducted in an area with an alfisol Soil in the Liaohe River plain, China. The trial, established in early 1990 and continued till 2007, included 8 combinations of recycled manure and N, P, and K fertilizers. In the unfertilized plot, the yields of soybean and maize were 1,486 and 4,124 kg ha−1 respectively (mean yield over 18 years). The yields of both soybean and maize increased to 2,195 and 7,476 kg ha−1, respectively, in response to the application of inorganic N, P, and K fertilizers. The maximum yields of soybean (2,424 kg ha−1) and maize (7,790 kg ha−1) were obtained in the plots under treatment with N, P, and K fertilizers and recycled manure. K was one of the yield-limiting macronutrients: regular K application was required to make investments in the application of other mineral nutrients profitable. The decrease in the yields of soybean and maize owing to the absence of K application averaged 400 and 780 kg ha−1, respectively. Soybean seed and maize grain yields significantly increased with the application of recycled manure. For both these crops, the variation coefficients of grain were lower with treatments that included recycled manure than without treatment. After 18 years, the Soil-exchangeable and non-exchangeable K concentrations decreased; the concentrations in the case of treatments that did not include K fertilizers were not significantly different. Treatment with N, P, and K fertilizers appreciably improved the fertility level of the Soil, increased the concentration of Soil-exchangeable K, and decreased the non-exchangeable K concentration. In Soils under treatment with N, P, and K fertilizers and recycled manure, the Soil-exchangeable and non-exchangeable K levels in the 0–20 cm-Deep Soil Layer increased by 34% and 2%, respectively, over the initial levels. Both Soil-exchangeable and non-exchangeable K concentrations were the highest with on treatment with N, P, and K fertilizers and recycled manure, followed by treatment with N, P, and K fertilizers. These concentrations were lowest in unfertilized Soils; the other treatments yielded intermediate results. The results showed a total removal of K by the crops, and the amount removed exceeded the amount of K added to the Soil; in treatments that did not include K fertilizers, a net negative K balance was observed, from 184 to 575 kg ha−2. The combined use of N, P, and K fertilizers and recycled manure increased the K content of the 0–20 cm-Deep Soil Layer by 125% compared to the increase obtained with the application of N, P, and K fertilizers alone. The results clearly reveal that current mineral fertilizer applications are inadequate; instead, the annual application of recycled manure along with N, P, and K fertilizers could sustain future yields and Soil productivity.
Hongsong Chen - One of the best experts on this subject based on the ideXlab platform.
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the characteristics of Soil water cycle and water balance on steep grassland under natural and simulated rainfall conditions in the loess plateau of china
Journal of Hydrology, 2008Co-Authors: Hongsong Chen, Mingan ShaoAbstract:Summary Large-scale vegetation restoration has been helpful to prevent serious Soil erosion, but also has aggravated water scarcity and resulted in Soil desiccation below a depth of 200 cm in the Loess Plateau of China. To understand the dynamic mechanism of Soil desiccation formation is very important for sustainable development of agriculture in the Loess Plateau. Based on natural and simulated rainfall, the characteristics of Soil water cycle and water balance in the 0–400 cm Soil Layer on a steep grassland hillslope in Changwu County of Shaanxi Loess Plateau were investigated from June to November in 2002, a drought year with annual rainfall of 460 mm. It was similarly considered to represent a rainy year with annual rainfall of 850 mm under simulated rainfall conditions. The results showed that the temporal variability of water contents would decrease in the upper 0–200 cm Soil Layer with the increase in rainfall. The depth of Soil affected by rainfall infiltration was 0–200 cm in the drought year and 0–300 cm in the rainy year. During the period of water consumption under natural conditions, the Deepest Layer of Soil influenced by evapotranspiration (ET) rapidly reached a depth of 200 cm on July 21, 2002, and Soil water storage decreased by 48 mm from the whole 0–200 cm Soil Layer. However, during the same investigation period under simulated rainfall conditions, Soil water storage in the 0–400 cm Soil Layer increased by only 71 mm, although the corresponding rainfall was about 640 mm. The extra-simulated rainfall of 458 mm from May 29 to August 10 did not result in the disappearance of Soil desiccation in the 200–400 cm Deep Soil Layer. Most infiltrated rainwater retained in the top 0–200 cm Soil Layer, and it was subsequently depleted by ET in the rainy season. Because very little water moved below the 200 cm depth, there was desiccation in the Deep Soil Layer in drought and normal rainfall years.
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Soil desiccation in the loess plateau of china
Geoderma, 2008Co-Authors: Hongsong Chen, Mingan Shao, Yuyuan LiAbstract:Abstract Soil desiccation usually takes place below the depth of Soil affected by rainfall infiltration (about 1–3 m) with relatively low water content, and is one kind of particular hydrological phenomena in semi-arid and semi-humid regions of the Loess Plateau in China. This desiccation results from the excessive depletion of Deep Soil water by artificial vegetation and long-term insufficient rainwater supply, which is difficult to disappear with land use change. Due to the influence of global warming during 1950–2000, large-scale vegetation rehabilitation aggravated water scarcity and led to Soil desiccation in the Deep Soil Layer in the Loess Plateau. From southeast to northwest, Soil desiccation becomes more intensive with lower water content and bigger range in depth due to drier climate and lower water holding capacity. The range of Soil desiccation has a close relationship with root distribution of plant, and its intensity varies with the types and ages of vegetation. The climate drought, Soil properties and Soil water cycle characteristics might be the precondition for the occurrence of Soil desiccation, and artificial vegetation with improper type and exorbitant productivity could have accelerated this process in range and intensity. Soil desiccation has obviously negative effects on water cycle in Soils, greatly reduces the anti-drought capacity of plants, and heavily influences the growth and natural succession of vegetation. In order to reduce the range, intensity, and negative effects of Soil desiccation, proper types of vegetation should be selected according to rainfall and Soil water conditions, and the control of vegetation density and productivity should be considered together with Soil-water conservation measures.
M H Wong - One of the best experts on this subject based on the ideXlab platform.
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organo chlorine pesticide ddt and hch residues in the taihu lake region and its movement in Soil water system i field survey of ddt and hch residues in ecosystem of the region
Chemosphere, 2003Co-Authors: Ke Feng, B Y Yu, D M Ge, M H WongAbstract:The use of organo-chlorine (DDT and HCH) has been banned in China for 20 years. A field survey was carried out during 1999–2000 in the Taihu Lake Region. Organo-chlorine pesticide (OCP) residues in Soil, water, fish and sediment samples were investigated. DDT was detected in 5 out of 10 samples with concentration ranging from 0.3 to 5.3 μg/kg in the surface (0–15 cm) Layer, 6 out of 10 with 0.5 to 4.0 μg/kg in the subSoil Layer (16–30 cm), and 4 of 10 with 0 to 2.7 μg/kg in the Deep Soil Layer (31–50 cm). Results for HCH residues in Soil samples were similar to those of DDT. These results indicate that OCP residues in 0–50 cm profile had been leached out or degraded to safe level. In river water DDT was detected in 10 out of 13 samples ranging from 0.2 to 9.3 μg/l, with an average of 1.0 μg/l. While HCH was detected in 12 out of 13 samples ranging from 0.02 to 36.1 μg/l, with an average 5.6 μg/l. DDT residues in sediment ranged from 0.1 to 8.8 μg/kg, while HCH ranged from 0.3 to 66.5 μg/kg. DDT residues in fish body ranged from 3.7 to 23.5 μg/kg and HCH ranged from 3.7 to 132 μg/kg. These results demonstrate an accumulation through food chain (from Soil–water–sediment–microbes–crop-fish–… etc.), also that HCH residues are generally more persistent than DDT residues. However, all these data are well below than the state warning standard limit.
Zishao Jiang - One of the best experts on this subject based on the ideXlab platform.
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effects of nutrient cycling on grain yields and potassium balance
Nutrient Cycling in Agroecosystems, 2009Co-Authors: Zishao Jiang, Hua ZhouAbstract:Soybean-maize rotation is a profitable cropping system and is used under rain fed conditions in north China. Since crop yields have been reported to decrease when K fertilizers are not used, we analyzed the productivity trends, Soil-exchangeable and non-exchangeable K contents, and K balance in a continuous cropping experiment conducted in an area with an alfisol Soil in the Liaohe River plain, China. The trial, established in early 1990 and continued till 2007, included 8 combinations of recycled manure and N, P, and K fertilizers. In the unfertilized plot, the yields of soybean and maize were 1,486 and 4,124 kg ha−1 respectively (mean yield over 18 years). The yields of both soybean and maize increased to 2,195 and 7,476 kg ha−1, respectively, in response to the application of inorganic N, P, and K fertilizers. The maximum yields of soybean (2,424 kg ha−1) and maize (7,790 kg ha−1) were obtained in the plots under treatment with N, P, and K fertilizers and recycled manure. K was one of the yield-limiting macronutrients: regular K application was required to make investments in the application of other mineral nutrients profitable. The decrease in the yields of soybean and maize owing to the absence of K application averaged 400 and 780 kg ha−1, respectively. Soybean seed and maize grain yields significantly increased with the application of recycled manure. For both these crops, the variation coefficients of grain were lower with treatments that included recycled manure than without treatment. After 18 years, the Soil-exchangeable and non-exchangeable K concentrations decreased; the concentrations in the case of treatments that did not include K fertilizers were not significantly different. Treatment with N, P, and K fertilizers appreciably improved the fertility level of the Soil, increased the concentration of Soil-exchangeable K, and decreased the non-exchangeable K concentration. In Soils under treatment with N, P, and K fertilizers and recycled manure, the Soil-exchangeable and non-exchangeable K levels in the 0–20 cm-Deep Soil Layer increased by 34% and 2%, respectively, over the initial levels. Both Soil-exchangeable and non-exchangeable K concentrations were the highest with on treatment with N, P, and K fertilizers and recycled manure, followed by treatment with N, P, and K fertilizers. These concentrations were lowest in unfertilized Soils; the other treatments yielded intermediate results. The results showed a total removal of K by the crops, and the amount removed exceeded the amount of K added to the Soil; in treatments that did not include K fertilizers, a net negative K balance was observed, from 184 to 575 kg ha−2. The combined use of N, P, and K fertilizers and recycled manure increased the K content of the 0–20 cm-Deep Soil Layer by 125% compared to the increase obtained with the application of N, P, and K fertilizers alone. The results clearly reveal that current mineral fertilizer applications are inadequate; instead, the annual application of recycled manure along with N, P, and K fertilizers could sustain future yields and Soil productivity.
