Targeted yield based fertilizer prescriptions for autumn rice (Oryza sativa L.) in inceptisols of Assam, India

Soil Test Crop Response (STCR) study was conducted during 2010–11 for autumn rice under integrated plant nutrition system (IPNS) in Inceptisols (Aeric Endoaquepts) in Jorhat district of Assam. The basic parameters were computed from the STCR data, and the fertilizer prescription equations were developed for recommending fertilizer doses in autumn rice. The nutrient requirement (NR) for producing one quintal of autumn rice was found to be 2.40 kg, 0.84 kg and 2.25 kg of N, P₂O₅ and K₂O, respectively. The percent contribution of nutrients from soil (CS), fertilizer (CF) and FYM (CO) were calculated as 12.49, 45.31 and 32.92 for N, 13.42, 28.52 and 11.84 for P₂O₅ and 21.99, 47.58 and 29.76 for K₂O, respectively. These equations were validated in farmers’ fields during 2012 and the variation between actual yield and targeted yield ranged from +1.36 to +5.33. The fertilizer estimates under STCR-IPNS for 3000 and 4000 kg ha⁻¹ targeted yield recorded maximum response ratio and economic benefit in the field trial and confirmed the validity of proposed fertilizer prescription equations for autumn rice.