Site Specific Nutrient Management for Targeted Yield of Groundnut (Arachis hypogaea L.) Under Drip Irrigation

A field study was conducted during rabi/summer 2014–15 to know the spatial variability of soil available nutrient content in different grids for site specific nutrient management in groundnut of the Eastern Dry Zone of Karnataka under the jurisdiction of University of Agricultural Sciences, GKVK, Bangalore, India. The site is located at 13^o 05’ 22" N latitude, 77^o 34’ 04" E longitude with an altitude of 933 m above mean sea level. The experimental fields have been delineated with each grid size of 9 x 9 m using geospatial technology and also DGPS, locations have been used to map the field variability. After grid making soil samples from 0-15cm were collected and analysed for different major nutrients in all the selected 36 grids. The soil was alfisol and it varied spatially for pH, EC, available nitrogen, phosphorous and potassium. The data observed on initial soil pH was from 4.82 to5.81 and electrical conductivity from 0.06 to 0.14 dSm⁻¹. Available nitrogen, phosphorus and potassium varied from 99 to 197, 12.1 to 64.0 and 129 to 382 kg ha⁻¹, respectively. Based on the understanding of the nature of spatial variability of soil nutrient availability and with the purpose of increasing profitability and sustainability of crop production a site specific nutrient management strategy was adopted. The results showed that, the application of nutrients through drip irrigation in 6 equal splits at fortnightly interval recorded significantly higher groundnut pod yield of 2524 kg ha⁻¹ over normal UAS (B) package of practice (1983 kg ha⁻¹). Significantly higher pod yield of 2735 kg ha⁻¹ was recorded as against the target 2500 kg ha⁻¹. The actual yield exceeded the target yield levels (1500, 2000 and 2500 kg ha⁻¹) by 37.0, 19.9 and 9.3 per cent respectively and application of NPK through drip irrigation in 6 equal splits at fortnightly interval recorded 28.6 per cent higher pod yield over blanket application as per UASB practice.