Potassium humate and NPK application rates influence yield and economic performance of potato crops grown in clayey loam soils

Potassium humate is one of the alternate sources of organic matter for improving physico-chemical properties of soils, crop growth and yield. The study investigated the effect of using different rates of potassium humate with and without recommended inorganic fertilizers in clayey loam soil on yield and economics of potato production. Four field experiments were conducted during 2010-11 and 2011-12 by using four levels of each, NPK (0, 50, 75 and 100% recommended dose) and potassium humate (0, 8, 12 and 16 kg ha) in a randomized complete block design (RCBD) with three replications. Tuber number, tuber fresh and dry weight and biological yield per hill, tuber yield per hectare and harvest index were significantly and positively affected by increasing level of NPK in both autumn and spring crops. Application of potassium humate significantly increased tuber fresh and dry weights (up to 10.95% and 14.43%; respectively), tuber yield (up to 10.96%), biological yield (up to 8.46%) and harvest index (up to 3.1) in both autumn and spring crops but improved tuber number per hill only in autumn crops. Application of full rate of NPK fertilizers with 16 kg ha potassium humate resulted in the highest tuber yield (19.749 tons ha). However, study results of benefit cost ratio indicated that application of NPK at 75% of recommended dose with 16 kg ha potassium humate remained the most economical for potato growers.