Responses of Rice Yield and Nitrogen Utilization to Straw Addition and Soil Layer Thickness

Objective The purpose of this study was to investigate the impact of straw addition and soil layer thickness on rice yield and the accumulation of nitrogen, in order to promote green and high-quality development of rice production.

Method Based on the current differences in soil layer thickness of paddy fields in Liaoning Province, a pot experiment and a two-factor completely randomized block design were utilized. A total of four treatments were set up, such as a shallow layer soil (15 cm) without straw addition (S − S), a deep layer soil (20 cm) without straw addition (D − S), a shallow layer soil (15 cm) with straw addition (S + S), and a deep layer soil (20 cm) with straw addition (D + S). Each treatment was replicated five times. By analyzing rice yield formation, accumulation and distribution of dry matter and nitrogen, nitrogen use efficiency at maturity, and by monitoring soil redox potential, rice growth status, and photosynthetic capacity of critical growth stages, the response mechanisms of rice yield and nitrogen utilization were elucidated to these factors.

Result The results showed that straw addition significantly increased rice yield, and there was no significant difference of the rice yield in the treatments with shallow and deep soil layers. Moreover, straw addition in the deep soil layer significantly increased the harvest index, especially in D + S treatment. Nitrogen accumulation proportion of panicle was significantly improved with straw addition, and the nitrogen harvest index and N partial factor productivity in S + S and D + S treatments were also increased. Moreover, at the maximum tillering and the flowering stage, the photosynthesis rates in the treatments of D − S, S + S and D + S were significantly enhanced, and the nitrogen nutrition status was improved as well.

Conclusion Therefore, straw addition in the deep soil layer treatment could increase the rice yield, promot the accumulation of dry matter and nitrogen in panicle, enhance the photosynthetic capacity and improve the nitrogen use efficiency.