Effects of conservation tillage on soil physicochemical properties in the spring maize area of the Loess Plateau

The values of soil bulk density,water content and seven kinds of soil nutrient content(organic matter,total nitrogen,available nitrogen,total phosphorus,available phosphorus,total potassium and available potassium) were evaluated in an agricultural soil,located in the spring maize area of the Loess Plateau,with three treatments such as no tillage(NT),conventional tillage+straw returning(TS) and conventional tillage(CT),in order to study the effects of conservation tillage on the changes of physical and chemical properties of soil in this zone.Samples were collected during the second year from the arable layer and four different stages.The results showed that the soil bulk density in the 0～10 cm soil depth under the treatment of no tillage was lower than that under conventional tillage in prophase of maize growth,but had a larger increase in the later growing stage;compared to conventional tillage,no tillage made a significant increase in soil water of 0～60 cm soil depth in the prophase of maize growth and 100～200 cm soil depth in the dough stage,and had a better effect on water storage;the contents of organic matter,total nitrogen,available nitrogen and available phosphorus in soil depth of 0～20 cm under conventional tillage were higher than those under no tillage,but had bigger coefficients of variation,while no tillage kept a rising trend of stability in most soil nutrient contents and made a higher contents in total potassium and available potassium.