Effects of complete basal application of coated potassium chloride on yield, fiber quality and soil available potassium of cotton

【Objectives】 Potassium(K) plays an important role on cotton production and fiber quality, the objective of the study was to investigate the effects of basal application of controlled release potassium chloride (CRK) on the yield, fiber quality and K use efficiency of cotton, to provide a theoretical basis for reasonable application of K fertilizer in cotton. 【Methods】 Pot experiments were conducted consecutively in 2012 and 2013 using cotton cultivar of “Guoxin 3” as materials. Six K treatments with four replications were designed: 1) no K application (CK); 2) complete basal application of potassium chloride (KCl); 3) 40% basal and 60% top-dressing at first bloom stage of potassium chloride (KClD); 4) complete basal application of potassium sulphate (KS); 5) 40% basal and 60% top-dressing at first bloom stage of potassium sulphate (KSD); 6) complete basal application of controlled release KCl (CRK). The soil available K contents in seedling, budding, first bloom, full bloom, initial boll-opening and mature stages were analyzed, the K uptake, the plant height and diameter of stems were measured; and the quality and yield of cotton were investigated. 【Results】 The contents of soil available K in CRK treatment were significantly higher at first bloom stage, full bloom stage, initial boll-opening stage and mature stage than in the KCl and K2SO4 treatments. The lint yield of CRK treatment was 23.6% higher than KCl, 15.6% higher than KS, 16.0% higher than KClD, but was not significantly higher than KSD. The lint percentage of CRK was significantly higher than KCl, but not significant than other treatments in boll weight and lint percentage. The fiber length, fiber elongation and strength of CRK were significantly higher than KCl and KS, but the micronaire and fiber uniformity were not. The K use efficiency of CRK was increased by 41.9%-50.9% than KCl, 27.3%-29.9% than KS and even 21.1%-25.2% than KClD. 【Conclusions】 The K releasing peak of controlled release potassium fertilizer in the experiment is 80-110 d, which is basically agreeable with the K uptake of cotton. Complete basal application of coated KCl could achieve increased cotton yield, improved fiber quality and enhanced K use efficiency, compared with common potassium fertilizer, no matter they are basal applied or basal plus top dressed. Therefore, potassium sulfate and potassium chloride could be replaced by controlled release potassium chloride fertilizer in cotton production.