Optimization of nitrogen fertilizer management for improving rice grain yield and nutrient accumulation and mobilization in saline‐alkaline soils

Abstract

AbstractSoil salinity and alkalinity are key abiotic stresses that limit crop growth and yield worldwide. Balanced N fertilization is important for improving rice (Oryza sativa L.) yield via efficient utilization of P and K under saline and alkaline soil conditions. In this study, a japonica rice cultivar, Kenjing 8, was used to investigate the effects of N fertilizer on rice yield, as well as N, P, and K status, in a 2‐yr field experiment in saline‐alkaline soil in Heilongjiang Province, northeast China. The plants were assigned to the following five treatment groups: no N fertilizer, or conventional, balanced, reduced, and postponed N fertilizer management. Compared with conventional N management practice, balanced and reduced N management practices increased the concentrations of N, P, and K in the leaves, stem‐sheaths, and panicles at full heading (FH) and maturity; however, postponed N management led to the opposite results. Balanced N management increased N, P, and K mobilization to the leaves (from FH to maturity) by 49, 43, and 67%, respectively, resulting in the highest crop yields among all the N management practices studied. Furthermore, rice yield was positively correlated with N, P, and K accumulation and rates of nutrient mobilization to the leaves, stem‐sheaths, and panicles at maturity. The application of 150 or 135 kg N ha−1, and the proportion of 4:3:1:2 in the pre‐transplanting, mid‐tillering, panicle initiation, and panicle differentiation stages, may increase rice yield and facilitate efficient utilization of nutrients in saline‐alkaline soil.