Effect of straw returning and nitrogen fertilizer regulation on nitrogen and rice yield in albic soil with different fertilities

Crop straw is a kind of carbon-rich energy material, which is important for maintaining and improving soil fertility and sustainable development of agriculture. According to the survey, the proportion of straw application in developed countries is above 70%, which is relatively lower in developing countries. The Sanjiang Plain is an important commodity grain base in China. While the main soil type of paddy field is albic soil. It is of great significance to carry out straw application experiment on albic soil. Early studies have shown that the average yields of albic soil paddy fields increased by 8.9% after the straw application for five consecutive years, but the study is limited to a specific plot. The effect of increasing the yield by the straw application on albic soils with different fertilities has not been reported. In this paper, albic soils with different fertilities were taken as tested soils, field comparison test method was adopted to perform straw mulching on high fertility albic soils, the straw was returned to field for three consecutive years from 2015 to 2017, the nitrogen fertilizer treatments was reduced by 10%, 20%, 30% according to the conventional application level of nitrogen fertilizer, and the experiment of returning straw to field and adding nitrogen fertilizer was carried on different fertility albic soils. This research compared the effect of continuous straw application to albic soils with different fertilities on rice yield though continuous investigation. The results showed that the continuous reduction of nitrogen by 10% in the high-fertility soil for three consecutive years increased the yield when compared with the control, increased by 0.1%-6.94%, the yield decreased when the application of nitrogen fertilizer decreased by more than 20% in the high fertility soil. In the first year of the implementation of straw application on the soils with high-fertilities, the yield increase by 4.47% compared with the control. In the second year, the yield of straw application and straw application + nitrogen treatment reduced by 4.02% and 31.86% respectively when compared with the control. The decreased range of application + nitrogen treatment was high; high-fertility soil was not suitable for the continuous straw application. In the second year, the yield of the straw application + nitrogen treatment on medium- and low-fertility soils increased by 1.48%, 4.52% compared with the control. When straw was returned to the field, the soil organic matter and nitrogen content were increased, and the amount of tillering in the early stage of rice was increased due to the high nitrogen content in high-fertility soil, the effective spike number of rice was reduced, the yield was reduced, the soil nitrogen was reduced after nitrogen reduction, the yield of rice was increased. The purpose of this study is to propose soil management techniques suitable for local conditions, so as to provide supporting field management techniques for the promotion of straw application in the paddy fields.