Effect of conservation tillage on wheat yield and soil physicochemical properties in the south of Loess Plateau

On basis of the longterm conservation tillage experiment located in Yaodu Distract, Linfen City of Shanxi Province from 1992, effects of the conservation tillage on wheat yield of rainfed land, soil physicochemical properties and soil water storage were studied. The results show that compared with traditional cultivation (TC), the average yields of wheat are increased by 192% and 276% in the 11yearno tillage land with stubble incorporating treatment (11y-NTS) and the 15yearno tillage land with stubble incorporating (15y-NTS) respectively, and the yields are increased by 52% and 117% in abundant precipitation year, while the yields are increased by 850% and 976% in dryyear. These results indicate that the effects of the conservation tillage on wheat yield are increased with the decrease of annual precipitation and the prolongation of implementing time; Soil bulk density is decreased, and soil total porosity, soil water content and water storage in the whole soil profile are increased under the conservation tillage. The contents of soil organic matter, alkalihydro N and available K in 0-10 cm soil layer are increased under the conservation tillage as well. However, the conservation tillage is not favor for the increase of available P, the contents of available P are decreased by 68 mg/kg and 63 mg/kg in the treatments of 11y-NTS and 15y-NTS, decreasing 561% and 519%, respectively, thus it is necessary to fertilize P properly.