Integrated Water and Nitrogen Management Practices to Enhance Yield and Environmental Goals in Rice–Ratoon Rice Systems

Abstract

Water and N management play a vital role in rice (Oryza sativa L.) production; however, limited information is available on the options to increase rice yield in rice–ratoon rice systems, including an appropriate combination of water regime (W), N application rate (NAR) and N application method (NAM). To address this question, field experiments were conducted with two Ws [simplified alternate wetting and drying (SAWD) and continuous flooding (CF)], four NARs (control, N0; 180 kg N ha−1, N180; 255 kg N ha−1, N255; and 330 kg N ha−1, N330) and two NAMs[45% of fertilizer pre‐plant, 15% of fertilizer at tilling, 40% of fertilizer at bud (BTB) and 45% of fertilizer pre‐plant, 15% of fertilizer at boot, 40% of fertilizer during grain filling (BPG)]. On average, the grain yields of the main crop, the ratoon crop, and their total for SAWD were 3.7%, 6.8%, and 4.4% higher than for CF, respectively. The relationships between NAR and the main crop, ratoon crop, and total yields were well fitted by quadratic equations. The rice yields of the main crop, ratoon rice, and their total under BPG were equal to or slightly higher than those under BTB. The interactive effect of W×NAR was significant on the main rice crop yield and total rice yield, but W×NAM, NAR×NAM and W×NAR×NAM were all related to the soil‐based yield. The use of integrated water and N management practices could achieve high yields and reduce water and N inputs in rice‐ratoon rice systems.Core Ideas The relationships between NAR and the main crop, ratoon crop, and total yields were well fitted by quadratic equations. The interactive effect of W×NAR was significant on the main rice crop yield and total rice yield, but W×NAM, NAR×NAM and W×NAR×NAM were all related to the soil‐based yield. The use of the SAWD‐N180–BPG treatment could achieve high yields and reduce water and N inputs in rice‐ratoon rice systems.