Effect of Sources, Levels and Methods of Potash Fertilization on Yield, Nutrient Uptake, Soil Chemical Properties and Quality of Rabi Onion in an Inceptisol

Abstract

A field experiment on rabi onion (cv. N-2-4-1) was carried out at an experimental farm of College of Agriculture, Pune during the winter season of 2016-17, to study the effect of different levels and sources of potash (0, 50, 100 and 150 kg K2O ha-1) and methods of its application as a basal (30% K2O at the time of transplanting, 40 per cent through fertigation after 30 days of transplanting till initiation of bulb formation and remaining 30 per cent through fertigation after 60 days of transplanting till bulb formation at weekly intervals respectively). In addition to that one more additional treatment of 100 kg K2O ha-1 was applied in the proportion of 90 kg K2O through MOP as a basal application + 10 kg K2O through SOP as a foliar spray @ 1% after 60 and 75 days after transplanting for comparing methods of K application. The results revealed that, the application of 100 kg K2O ha-1 (90 kg K2O ha-1 as basal at the time of transplanting through MOP and 10 kg K2O through two foliar sprays of SOP at 60 and 75 days after transplanting) recorded maximum fresh bulb weight, dry matter yield, and higher bulb diameter, the higher nutrient uptake of nitrogen, phosphorus, potassium, sulphur, Fe, Mn, Zn and Cu uptake by rabi onion. The perceptible improvement in available N,P,K , S and Mn content of soil due to application of 150 kg K2O ha-1 through SOP applied through soil and fertigation over control. The application of 100 kg K2O ha-1 (SOP) through soil and fertigation or 100 kg K2O ha-1 was applied in the proportion of 90 kg K2O through MOP as a basal application + 10 kg K2O through SOP as a foliar spray @ 1% after 60 and 75 days of transplanting recorded magnitudely lower mean physiological loss in weight.