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A field experiment was conducted on a sandy loam soil during kharif season of 2012 with a view to study the effect of Site specific nitrogen management in rice on nutrient uptake, N use efficiency and grain yield. The leaf colour chart (LCC) and SPAD based N management can be used to optimize N application with crop demand or to improve existing fixed split N recommendations. We conducted a field experiment to determine the LCC and SPAD critical value for N application in irrigated rice. Treatments included 3 LCC based and 3 SPAD based N management contained the combination of three critical levels of LCC shade values (4, 4.5, 5) and three critical levels of SPAD (37, 39 and 41) values with different levels of N application were compared with recommended fertilizer dose (RFD) and soil test crop response (STCR) equation based fertilizer application. Nitrogen was applied in the form of urea as per treatment schedule and the SPAD and LCC assessed at 10 days intervals starting from 15 DAT. Result showd a considerable opportunity to increase yield, N use efficiency (NUE) and nutrient uptake through improved N management with LCC and SPAD values. The critical SPAD value of 41 with 30 Kg N ha-1 and critical LCC value of 4.5 with 30 kg N ha-1 were found to be suitable for guiding N application to achieve the highest grain yield.
Keywords: Kharif, Rice, Yield, STCR.