Evaluation of critical limits of potassium in plant for upland paddy grown on shrink-swell soils

Abstract

The critical limits of potassium in plant for upland paddy was determined through a pot culture experiment with shrink-swell soils. The samples of eighteen different locations were collected having low ( 250 kg K2O ha-1) potassium status. The present investigation was carried out in Factorial Completely Randomized Design with two treatments (viz. 0 and 50 kg K2O ha-1) and two replications. The paddy crop was harvested at 100 per cent flowering. The critical limits of potassium in plant were worked out according to method of Cate and Nelson (1965 and 1971). The dry matter yield (g pot-1) of paddy plant ranged from 34.49 to 49.77 g pot-1 amongst 18 locations. There was a significant increase in dry matter yield due to application of potassium. The critical limit of potassium in paddy plant at 100 per cent flowering for shrink-swell soils was found 1.39 per cent by graphical method (Cate and Nelson, 1965) and 1.41 per cent by statistical method (Cate and Nelson, 1971), respectively. The results indicated that, paddy plant containing less than 1.41 per cent potassium at 100 per cent flowering, respond to application of potash fertilizers.