Soil salt transformation plays an important role in the freeze-thawing process,which is also one of basic problems of cryopedology. The very special law is made up of the two time salt-moisture transfer under freeze-t...Soil salt transformation plays an important role in the freeze-thawing process,which is also one of basic problems of cryopedology. The very special law is made up of the two time salt-moisture transfer under freeze-thawing condition. Based on the latest research at home and abroad,through the investigation of soil moisture-salt change in the freeze-thawing process,the conclusion is made that the soil water potential gradient is the main driving force of soil salt movement and the factors are of quantities. The research shows that,when freezing,temperature drops,salt and moisture move towards frozen layer. All make the salinity content of the frozen layer increase significantly. In the thawing process,salinity and moisture in the soil move up again with evaporation and makes the salt second migration.展开更多
The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax...The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax￣b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a andb are the regression constants). The depletion rate of phosphate in soil near the root surface was higher andthe depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content thedepletion range was wider, generally The application rate of phosphate led to the greater depletion intensityof phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, whichdecreased with increasing clay content or increa.sing buffering power of soil, decreased in the order as loessalsoil and black fou soil> lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in theform of KH_2PO_4. This result indicated that the phosphate distribution and its movement in the soil-rootinterface zone closely related with the buffering capacity of soil.展开更多
Soil particle size distribution(PSD),one of the most important soil physical attributes,is of great importance to soil water movement,soil erosion and soil solute migration.In this study,the soil PSD of 563 soil sampl...Soil particle size distribution(PSD),one of the most important soil physical attributes,is of great importance to soil water movement,soil erosion and soil solute migration.In this study,the soil PSD of 563 soil samples from the mulched drip irrigated cotton fields in Xinjiang of China were measured by laser diffraction particle size analyzer.The soil PSD characteristics and its relations with soil water and salt were studied by using the combined methods of textural triangle,fractal and multifractal analysis.The results showed very low clay content(about 1.52%) while really high sand content of the studied soil,and a complex shape of bimodal or unimodal of soil PSD.The results also showed that the two indices,i.e.,standard deviation and the peak value of soil particle relative volumes,were good indicators of soil PSD and thus had good relations with fractal and multifractal characteristics.The correlative analysis further indicated that the mulched drip irrigation had a significant impact on the distribution of the soil salt,while this impact withered for the deeper soil layer.The soil texture feature was found to dominate soil water and salt distribution,especially the surface soil salt content and the deep soil water content.展开更多
文摘Soil salt transformation plays an important role in the freeze-thawing process,which is also one of basic problems of cryopedology. The very special law is made up of the two time salt-moisture transfer under freeze-thawing condition. Based on the latest research at home and abroad,through the investigation of soil moisture-salt change in the freeze-thawing process,the conclusion is made that the soil water potential gradient is the main driving force of soil salt movement and the factors are of quantities. The research shows that,when freezing,temperature drops,salt and moisture move towards frozen layer. All make the salinity content of the frozen layer increase significantly. In the thawing process,salinity and moisture in the soil move up again with evaporation and makes the salt second migration.
文摘The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax￣b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a andb are the regression constants). The depletion rate of phosphate in soil near the root surface was higher andthe depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content thedepletion range was wider, generally The application rate of phosphate led to the greater depletion intensityof phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, whichdecreased with increasing clay content or increa.sing buffering power of soil, decreased in the order as loessalsoil and black fou soil> lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in theform of KH_2PO_4. This result indicated that the phosphate distribution and its movement in the soil-rootinterface zone closely related with the buffering capacity of soil.
基金supported by the National Key Technology R & D Program of China (Grant No 2007BAD38B01)the National Science Founda-tion for Post-doctoral Scientists of China (Grant No 20100470297)
文摘Soil particle size distribution(PSD),one of the most important soil physical attributes,is of great importance to soil water movement,soil erosion and soil solute migration.In this study,the soil PSD of 563 soil samples from the mulched drip irrigated cotton fields in Xinjiang of China were measured by laser diffraction particle size analyzer.The soil PSD characteristics and its relations with soil water and salt were studied by using the combined methods of textural triangle,fractal and multifractal analysis.The results showed very low clay content(about 1.52%) while really high sand content of the studied soil,and a complex shape of bimodal or unimodal of soil PSD.The results also showed that the two indices,i.e.,standard deviation and the peak value of soil particle relative volumes,were good indicators of soil PSD and thus had good relations with fractal and multifractal characteristics.The correlative analysis further indicated that the mulched drip irrigation had a significant impact on the distribution of the soil salt,while this impact withered for the deeper soil layer.The soil texture feature was found to dominate soil water and salt distribution,especially the surface soil salt content and the deep soil water content.
