Effects of the returned straws with different crushing degrees on the physical and chemical properties and water flow characteristics of red soil
[Objective]The aim of this study is to illustrate the impacts of the returned straws with different crushing degrees on the physical and chemical properties and the characteristics of water flow movement in red soil,and to provide a reference for the management of straw returned to farmland in the red soil zone of southern China.[Methods]Laboratory experiments with different kinds of straws(corn straw and rice straw)and different degrees of straw crushed(10-mesh size powder,3～5 cm length chopped and 30 cm length chopped)were conducted to study the effects of straw returning to field on soil physical and chemical properties(i.e.organic matter content,ammonia nitrogen content,available phosphorus content,soil bulk density,aggregate stability and available potassium content)and heterogeneous soil water flow characteristics.[Results]All the three kinds of straw returning methods of corn straw and rice straw increased the soil organic matter content in both returning and non-returning soil layers.Specially,the soil organic matter content increased by 30.84％and 41.63％in the returned soil layers of powered corn straw and rice straw returning,respectively.Though all the three kinds of corn straw and rice straw returning methods had the ability in increasing the content of nitrogen,phosphorus and potassium in soil,ammonia nitrogen decreased by 21.49％and 27.83％,and available phosphorus decreased by 17.62％and 23.29％,in the returned soil layers and at the prophase of corn straw and rice straw returning,respectively.Thus,the application of nitrogen and phosphate fertilizer with straw returning was necessary in engineering to alleviate the deficiency of nitrogen and phosphorus elements in soil at the prophase after straw returning.All the three kinds of straw returning methods of corn straw and rice straw increased the average weight diameter of soil aggregates and decreased soil bulk density in returned soil layer.Specially,the average weight diameter of soil aggregates increased by 176.19％and 200.95％,and the soil bulk density decreased by 7.50％and 8.33％in the returned soil layers of powered corn straw and rice straw returning,respectively.All the three kinds of straw returning methods of corn straw and rice straw increased the preferential soil water flow heterogeneity.Specially,the overall and lateral preferential flow heterogeneity coefficient increased by 1.25～2.02 times and 5.44～6.05 times of integral corn straw and rice straw returning,respectively.[Conclusion]The higher the degree of straw crushed,the faster it improves the physical and chemical properties of the soil,but it also increases the heterogeneity of water flow movement.
red soilstraw returningsoil organic mattersoil nutrientssoil structuresoil propertyprefer-ential flow
万方数据
维普
