Impacts of minimum tillage and no-tillage systems on soil NO^-₃-N content and water use efficiency of winter wheat/summer corn cultivation

In order to research the impacts of minimum tillage and no-tillage on crop yield, crop water use efficiency and soil NO^-₃-N content under the condition of winter wheat/relays summer maize cultivation and irrigation field, five tillage systems were adopted in Longkou city, Shandong Province. The five tillage systems were as follows: conventional tillage without straw turnover , conventional tillage with straw turnover, rotary tillage with straw turnover, serrated disk harrow tillage with straw turnover, no-tillage with straw cover. The soil moisture content was measured by oven drying method. The soil NO^-₃-N content was measured by continued flow analysis extraction. Results showed that minimum tillage especially rotary tillage with straw returned could increase soil water content, water use efficiency and crop yield in a whole year, NO^-₃-N content in 0～60 cm layer of soil and decrease the leaching loss of NO^-₃-N in soil. Preliminary studies showed that rotary tillage with straw turnover could be adopted in this region, while no-tillage with straw cover returned was not suitable.