Site-Specific Nutrient Management Practices for Targeted Corn and Pigeonpea Yield in Alfisols of Karnataka, India.

Unbalanced and non-site specific fertilization of crops results in lower grain yields and create problematic soils. We hypothesized that site specific nutrient management (SSNM) based on assessment of crop nutrient requirement increases grain yield, profitability and nutrient use efficiency. Studies were conducted during 2006 and 2007 at Dryland Research Centre, Bangalore, India and on-farm dryland sites in Karnataka with two varieties of corn (Zea mays L.) and pigeonpea (Cajanus cajana L.), seventeen NPK levels with and without sulphur and zinc. Field and season specific N, P and K applications were calculated by accounting the indigenous nutrient supply, yield target and nutrient demand per tonne of produce. Pre-season soil test results indicated that the soils were medium in nitrogen and phosphorous with high potassium. For SSNM practice attainable target yield of 8 t ha^-1 and 4 t ha^-1 was fixed for corn and pigeon pea, respectively. Corn hybrid such as NAH-2049 and pigeonpea variety BRG-2 produces higher dry matter, yield and nutrient use efficiency. The yield response under SSNM practice was up to 42 per cent in corn (6.5 t ha^-1) and 47 per cent in pigeonpea (1.87 t ha^-1) over normal NPK application. Additional corn grain yield was obtained with the application of zinc (10 kg ha^-1 each) and sulphur (865 kg ha^-1 and 987 kg ha^-1) compared to normal NPK. Average nutrient use efficiency increased by 30-35 % and plant NPK uptake by 8 to 14% under SSNM treatment. However, corn oil (5 to 6.6 %) and crude protein (10.8-14.2 %) content was not much affected due to nutrient levels and varieties. Our results showed that SSNM practice enhanced grain yield and nutrient use efficiency in corn and pigeon pea hybrids.