RAMAKRISHNA PARAMA, V. R.ATHEEFA, MUNAWERY2017-03-032017-03-032013-12-12Th-10708http://krishikosh.egranth.ac.in/handle/1/5810003767Potassium is an essential nutrient for growth and development of crops, which is being depleted in Indian soils due to very low applications. The present study conducted during 2010-11 on Alfisol addresses the above issue. Field and pot experiments were carried out to determine the effect of graded levels of potassium on growth and yield of crops and soil properties under nutrient gradient strips and to revalidate the optimum dose of K required for maize in soils of eastern dry zone of Karnataka where K status was low to medium. Field experiments indicated higher grain yield (3287.67 and 7762.00 kgha-1 respectively) in-case of fingermillet and maize was recorded in T6 (200%K+Rec.NP+FYM) of very high K fertility gradient strip (K4). High major, secondary and micronutrients in soils with increase in potassium fertility gradients (K0 to K4). Calcium and magnesium decreased from Control (T1) to treatment T7 (200%K+Rec.NP). A comparison of K added and taken-up which is referred to as K balance indicated a negative value in-case of (T1, T2, T4 and T6) in very low K gradient (K0) whereas (T1, T2, T3 and T5) recorded negative value in low K gradient (K1) strip respectively, this was in-case of fingermillet whereas in maize T1 of K0 gradient recorded negative K balance, all other treatments in other K fertility gradients recorded positive balance. Water soluble, exchangeable, non-exchangeable and total potassium in soil after fingermillet–maize sequence increased with increase in levels of potassium application. Results of pot experiment indicated critical limit of 105 kg K ha-1 for soil available K and 1.72% plant K for maize crop. The soil available K can be revalidated as <105 kg ha-1 very low, 106 to 215 kg ha-1 low, 216 to 380 kg ha-1 medium and >380 kg ha-1 as high in available K respectively.ennullThesis