Rice straw nitrogen can be utilized by rice more efficiently when co-incorporating with milk vetch

Abstract

The co-incorporation of milk vetch (MV) and rice straw (RS) in paddy field can promote nitrogen (N) uptake of rice, but the mechanisms of increased N utilization and contributions of milk vetch N (N_MV) or rice straw N (N_RS) to rice N uptake are still unclear. Two long-term field experiments and a ¹⁵N dual-label pot experiment were established to explore the effects of co-incorporation of milk vetch and rice straw on the fate and utilization of milk vetch N and rice straw N in the rice cropping system. Results of the field experiments showed that co-incorporation of MV and RS increased the rice N uptake by 45.0 % at two sites on average, compared to single RS return. The ¹⁵N dual-label pot experiment indicated that compared to single RS, co-incorporation of MV and RS increased the N_RS uptake and N_RS recovery of rice by 53.2 % and 53.4 %, respectively, and the N_RS recovery in soil was increased by 55.4 %. This study concluded that co-incorporation of MV and RS facilitated the efficient utilization of N_RS by increasing N_RS uptake of rice and recovery in soil.