Effects of Long-term all Straw Return to Field with Machine on the Stratifications of Soil Nutrients

This study investigated the stratifications of soil nutrient under the two types of land utilization, orchard and cropland cultivated with all straw return to filed with machine for 13 years, in Linwei District, Weinan. Soil organic carbon, active organic carbon, total nitrogen, available phosphorus, and available potassium were analyzed. This study will provide scientific reference for the stratifications of soil nutrients under different types of land utilization and straw return. The results showed that the contents of soil organic carbon, active organic carbon, total nitrogen, available phosphorus, and available potassium decreased with the soil profile depth under the two types of land utilization. The effects of two types of land utilization on the stratifications of soil nutrients were different. The stratification ratios of soil nutrients(except for available phosphorus) in soil profile depth were larger in cropland than that in orchard. After straw was returned to soil, the contents of soil nutrients in the topsoil(0 ~ 5 cm) were significantly higher in cropland than in orchard, and the differences between different depths of soil profile in stratification ratios of soil nutrients were larger in cropland than in orchard. The results suggested the long-term all straw return to field with machine could promote the stratifications of soil nutrients.