Effects of Tillage Methods on Soil Available Phosphorus and Available Potassium in the Loess Plateau

In order to find out the effects of long-term no-tillage operation on soil available phosphorus and available potassium in the loess plateau, a suitable high-yield and high-efficiency tillage technology system was established. In the Changwu loess plateau agri-ecological experiment station of the Northwest A&F University of Changwu County, Shaanxi Province, the no-tillage experimental field for three consecutive years was selected. In September 2015, no-tillage, tillage, and rotary tillage were carried out before winter wheat was sowed. After the harvest of winter wheat in 2016, the contents of available phosphorus and available potassium in 0-30 cm soil layer under three tillage methods were analyzed. The results showed that in the 0-30 cm soil layer, the soil available phosphorus and available potassium decreased with the increase of the soil depth in the three tillage methods. The content of available phosphorus and available potassium in10-20 cm soil layer and 20-30 cm soil layer decreased by 16.07%, 32.74%, 15.54% and 27.08%, respectively, and there were significant differences (P < 0.05). Under different tillage methods, the soil available phosphorus content in the 0-10 cm soil layer significantly reduced by 11.31% compared with no-tillage. The soil available potassium content under tillage and rotary tillage significantly reduced by 6.16% and 4.97%, respectively (P < 0.05). Compared with no-tillage, the soil available phosphorus content in the 20-30 cm soil layer significantly reduced by 18.12%. The soil available potassium content under tillage and rotary tillage methods significantly reduced by 17.17% and 9.22%, respectively (P < 0.05). Therefore, in the long-term no-tillage dry loess plateau, it is necessary to conduct proper tillage or rotary tillage.