Contribution of Nutrients through Critical Irrigation from Diverse Water Sources in Selected Watersheds of Semi-arid Tropical India

Ch Srinivasa Rao et al., 'Contribution of Nutrients through Critical Irrigation from Diverse Water Sources in Selected Watersheds of Semi-arid Tropical India', Indian Journal of Dryland Agriculture Research and Development, vol. 27(1), pp.58-69, The Indian Society of Dryland Agriculture, 2013

Critical irrigation is one of the most important management options to protect the crop duringweather aberrations like dry spells at critical stages of the crop growth in semi arid condition. Various waterharvesting structures are useful in watershed areas to cope up with mid-season droughts. These structures providecritical irrigations at sensitive crop growth stages by which they supply essential nutrients to some extent. Weestimated the contribution of various sources of water in terms of plant nutrients and to what extent criticalirrigations meet nutrient requirements of various crops. By giving 4 cm irrigation, the maximum major nutrient(kg ha-1) addition in the studied watersheds is of the following order NO3 (5.2, Kothapalli); SO4 (15.2, Kolar); Na(72.0, Haveri); K (3.6, Govardhanapura); Ca (38.5, Semli and Shyamapura); Mg (20.5, Kothapalli) and formicronutrients (g ha-1) Fe (109, Kolar); Zn (40, Kothapalli); Mn (90, Kolar); Cu (120, ICRISAT) and B (190,ICRISAT). Percentage of recommended dose of nutrients which can be met by three irrigations in cereal crops (5-10, 15-100, 10-20% in N,S,K respectively); legumes (5-30,10-100, 5-10% of N,S,K respectively); cotton (10-15,25-30, 5-10% of N,S,K, respectively) and micronutrients such as Fe, Zn, Mn, Cu and B to the full extent. With thenumber of critical irrigations increased, application of secondary and micro nutrients should be avoided whichotherwise leads to higher cost of alleviation and environmental pollution