Effect of potassium and organic manures on the growth performance of cowpea (Vigna unguiculata) in sandy regosols

Abstract

In Sri Lanka due to continuous changes in climate, drought is becoming as a serious problem in Agriculture. Batticaloa district is one of the intensive agricultural region in the eastern province of Sri Lanka and mostly affected by drought during yala season. Major soil group found in this region is sandy regosols. According to the characteristics of sandy regosols it is low in agricultural value. Therefore proper management practices should be adopted to improve the performance in agricultural productivity. Soil moisture is the principal environmental factor that limiting the legume productivity in tropical countries. Potassium fertilization facilitates the crops to survive under drought stress and helps to obtain better performance. A pot experiment was carried out at Eastern University, Sri Lanka during the period of July to September 2018, to evaluate the effect of organic manures and rate of potassium on the growth performance of cowpea (Vigna unguiculata) in sandy regosol using variety wijaya. There were eight treatments combining cow dung and compost with muriate of potash at the rate of 100%, 125%, 150% and 175% of recommendation and were replicated three times in two factor factorial completely randomized design (CRD). Among the organic manures compost showed highest growth performance than cow dung. Increasing rate of potassium increased the growth and yield of cowpea and highest yield was obtained at the combination of compost with 175% recommendation of MOP. Therefore combination of compost with increasing rate of MOP can be suggested to farmers especially for the cultivation of cowpea on sandy regosols in order to obtain best growth and yield performance and to indirectly avoid excess watering during drought condition.