Performance of Site‐Specific Nutrient Management for Irrigated Rice in Southeast China
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Rice (Oryza sativa L.) yield increases in Zhejiang, China have slowed since 1985 despite the increasing use of hybrids and fertilizers. On-farm experiments at 21 sites were conducted to evaluate a new approach for site-specific nutrient management (SSNM), Field- and season-specific N-P-K applications were calculated by ac counting for the indigenous nutrient supply, yield targets, and nutrient demand as a function of the interactions between N, P, and K. Nitrogen applications were fine-tuned based on season-specific rules and field-specific monitoring of crop N status. The performance of SSNM was tested For Four successive rice crops. Compared with the current farmers' fertilizer practice (FFP), average grain yield increased from 5.9 to 6.4 Mg ha-L while plant N, P, and K uptake increased by 8 to 14%, The gross return over fertilizer cost was about 10% greater with SSNM than with FFP, Yields were about 20% greater in late rice (hybrid cultivars) than in early rice (inbred cultivars), but SSNM performed equally better than FFP in both seasons. Improved timing and splitting of fertilizer N increased N recovery efficiency from 0.18 kg kg(-1) in FFP plots to 0.29 kg kg(-1) in SSNM plots. The agronomic N use efficiency (grain yield increase per kilogram fertilizer applied) was 80% greater with SSNM than with FFP, As defined in our study, SSNM has potential for improving yields and nutrient efficiency in irrigated rice. Future research needs to develop a practical approach for achieving similar benefits across large areas without field-specific modeling and with minimum crop monitoring.
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