Effects of Method for Returning Straw to Field on Soil Properties, Straw Decomposition and Nutrient Release

[Objectives] To alleviate the influence of meteorological conditions on soil environment (temperature and water content) and maintain high and stable grain yield. [Methods] Taking Sunzhen Experimental Station of Weinan Academy of Agricultural Sciences as the experimental base, the effects of returning double-crop wheat and corn straw to field (Twm), returning single-crop corn straw to field (Tm), returning single-crop wheat straw to field (Tw) on soil temperature, water content, straw decomposition rate and nutrient release, soil organic matter and bulk density were studied systematically. [Results] Twm treatment could effectively alleviate the effects of meteorological conditions on soil temperature and water content. The decomposition rate of straw treated with Twm was 4.7% higher than that of Tm treatment, 3.8% higher than that of Tw treatment, 10.5% higher than that of Tm treatment, and the decomposition rate of straw showed a trend of "first fast, then slow and then fast". The release of nitrogen from straw was basically similar to that of straw decay, and the release of potassium and phosphorus increased at first and then remained basically unchanged. The release rate of potassium was the highest, followed by phosphorus and nitrogen. The content of soil organic matter in Twm treatment increased by 11.67% annually, an annual average of 0.998 g/kg . The soil bulk density of Twm treatment decreased by 0.058 g/cm3 annually, an annual average of 4.29% . The fundamental reason is that Twm treatment provides conditions (temperature, water content, nutrition) for microbial growth, reproduction, enzyme production and biochemical reaction, and increases the exchange capacity of soil and external water, heat, gas and fertilizer. [Conclusions] The purpose of this paper is to help people change their understanding of returning straw to field from "quick harvest" to "fertilizer transformation".