EFFECT OF SPLIT APPLICATION OF POTASSIUM ON GROWTH, YIELD AND POTASSIUM ACCUMULATION BY SOYBEAN

Field experiments were conducted during 1989 to 1991 on a loamy sand ( Typic ustochrept) soil to study the K nutrition of soybean. Soybean re sponded significantly up to 50 kg K ha(-1) when applied 1/2 of K at pl anting and 1/2 at flower initiation (two split) or applying 1/3 K at p lanting, 1/3 at flower initiation and 1/3 at pod development (three sp lits). Split application was more beneficial than applying full K at t ime of planting due to higher leaf area index, crop growth rate, chlor ophyll content of fresh leaves, K accumulation in soybean and better a gronomic and physiological efficiency of applied K. Agronomic efficien cy, physiological efficiency and apparent recovery of K reduced as rat e of applied K was increased from 50 to 75 kg ha(-1). Highest K+ conce ntration (3.4 % of dry matter) was recorded in 30-day-old plants at 75 kg K ha(-1) which depressed progressively with the age of the crop. A t maturity, the K concentration of soybean seed varied from 1.5% (unfe rtilised K plants) to 2.1 % (when 75 kg K ha(-1) was applied in three splits).