Regulation and effect of 100% straw return on crop yield and environment

Incorporation of crop straw into the soil is an major soil management practice that improves soil fertility for sustainable agriculture. However, its application is severely hindered by low economic efficiency, low yield and negative environmental effects. This paper reviewed the effects of returning 100% of crop straw into the soil on crop yield, the mechanism and characteristics of straw decomposition, and environmental effects and regulation of straw return. For this purpose, the paper reviewed a huge number of published scientific research papers on the progresses of the effects of crop straw return into the soil. The results showed that 100% straw return improved soil fertility and increased yield of wheat and rice, which increased with increasing time of straw return. The decomposition rates of wheat and rape straws were 50%?66% during rice growing season, respectively releasing 42%?58%, 55%?68% and 92%?98% of total straw nitrogen (N), phosphorous (P) and potassium (K) into the soil. Straw return significantly increased soil organic carbon storage and reduced runoff loss. However, it enhanced CH4 emission, ammonia volatilization and nutrient loss through leaching. In order to mitigate the negative effects of straw return on economic growth and the environment, it was necessary to increase the proportion of N fertilization at the early stage of rice and wheat growth, properly reduce the N fertilization dose during whole growing season, and reduce P fertilization and especially K fertilization rates. In order to reduce CH₄ emission, it was recommended to apply straw return during dry periods and use intermittent flood/moist irrigation during rice growing season.