PRAKASH, S. S.VIJAY KUMAR, C.2017-07-082017-07-082015-04-10256http://krishikosh.egranth.ac.in/handle/1/5810024700Survey of salt affected soils in four selected locations of Cauvery Command Area indicated that soils are sandy clay loam to clay in texture, slightly acidic to alkaline in reaction (pH 6.2-10.6) with ECe in the range between 0.4 and 11.7dS/m. Soils were low to medium in organic carbon, N, P, K, Ca, Mg, S and micronutrients (Zn, Cu, Fe, Mn and B). Profile studies showed that soil pH, organic carbon and available N decreased with depth. Sodium was the most dominant cation and the ESP of the soils ranged from 1.1 to 58.6. The lowlands have higher sodium and ESP than uplands. The per cent samples falling under salinity and alkalinity or both were 71, 72, 65 and 83 in site 1, 2, 3 and 4, respectively. Field experiments were conducted at ZARS, V. C. Farm, Mandya during Kharif 2013 and summer 2014 to assess the growth and yield response of rice to nutrient levels and ratios in gypsum amended sodic soil. The experiment were laid out in a randomized complete block design with nineteen treatment combinations and replicated thrice. The results revealed that application of gypsum @ 100% GR and 150:50:50 kg NPK/ha (3:1:1) recorded significantly higher grain (5.37 t/ha) and straw (6.79 t/ha) yield of rice, nutrient content and uptake (129.5, 35.6 and 84.3 kg NPK ha-1) as compared to other nutrient levels and ratios. Further higher secondary and micronutrients content and uptake, nutrient use efficiency, higher gross and net monetary returns and higher B:C ratio (1.86) and decreased pH, ECe and ESP were recorded in the same treatment. The study clearly showed that in sodic soils, application of gypsum @ 100% GR and NPK (150:50:50 kg/ha) is more beneficial in enhancing the crop yield, crop productivity as well as soil fertility.ennullThesis