Site-specific fertilizer nitrogen management in irrigated transplanted rice (Oryza sativa) using an optical sensor

摘要: Blanket fertilizer nitrogen (N) recommendations for large irrigated transplanted rice tracts lead to low N use-efficiency (NUE) due field-to-field variability in soil supply and seasonal yield. To achieve high NUE, a management strategy based on visible near-infrared spectral response from plant canopies using GreenSeeker™ optical sensor was evaluated. Seven field experiments were conducted during 2005–2007 at two locations the Indo-Gangetic plains of South Asia define relationships between in-season measurements panicle initiation (PI) stage up 2 weeks later, yield rice. During 2006–2010, seven assess sensor-based work out prescriptive be followed prior applying sensor-guided dose. 2010 2011, sensor- evaluated versus farmers’ practice 19 on-farm locations. Relationships with R2 values 0.51 (n = 131), 0.45 (n = 74) 0.49 respectively, observed estimates 42 (PI stage), 49 56 days after transplanting actual grain Applications 30 kg N ha−1 45 kg N ha−1 active tillering found appropriate before GreenSeeker-guided dose PI stage. Sensor-guided resulted similar yields as blanket rate farmer practice, but reduced rates, i.e. greater recovery efficiency (by 5.5–21.7 %) agronomic [by 4.7–11.7 kg (kg N applied)−1]. This study revealed that coupled NUE can achieved by replacing recommendation an consisting moderate amount enough meet demand period