Integrating optimal fertilizer placement strategy and row configuration for high yield, high economic benefits and fewer environmental footprints in direct-seeded rice

Conventional multi-split nitrogen (N) application by broadcasting (CSB) often leads to reduced yields and lower nitrogen use efficiency (NUE) in direct-seeded rice. One-time root zone targeted fertilization (ORZTF) has been suggested as an effective alternative to improve grain yields and NUE. However, the optimal fertilization distance and its systematic impacts on productivity and environmental sustainability under ORZTF in direct-seeded rice remain unexplored. To address this, two field experiments were conducted at Huanghai Farm in Jiangsu Province. The first experiment (2021–2022) evaluated the effects of ORZTF at key distances (10 cm, 14 cm, 18 cm, and 22 cm) on yield and NUE. The second experiment (2021 −2023) assessed an alternative row (AR) fertilization approach, rigorously evaluating ORZTF’s effects on yield, economic viability, and environmental impact. Results demonstrated that ORZTF at 14 cm achieved the highest yield by maintaining productive tiller numbers, chlorophyll content, and enhancing N uptake compared to CSB. Additionally, the AR approach based on a 14 cm distance increased average yield by 6.8 % over three years by improving root development and raised net economic benefits by 12.6 %. Furthermore, every-row (ER) fertilization significantly boosted ¹⁵N accumulation in plants and soil by 76.9 % and 48.9 %, respectively, while reducing potential ¹⁵N loss by 39.5 % compared to CSB. Both ER and AR minimized N concentrations in floodwater and reduced ammonia volatilization (NH₃) to levels comparable to no-N treatment. In summary, optimizing fertilizer placement intervals and row configuration can enhance yields, economic benefits, and environmental sustainability in direct-seeded rice.