Potassium sources in covering fertilization on cotton II - Nutritional status evaluation of crop

Abstract

A field experiment was conducted in Sapezal, Mato Grosso state, Brazil, in the 2007/2008 agricultural season, with the aim of determining the effect of potassium sources on cotton nutritional status. The treatments consisted of application in covering, via soil, at rate of 100 kg ha^-1 of K₂O, in two split applications, with KCl, K₂SO₄, KNO₃ and K₂SO₄.2MgSO₄ sources. Nutrients concentration in leaf tissues at bloom stage was evaluated, being interpreted by the critical level and the DRIS methods. S content in cotton leaves and the S index was higher when used K₂SO₄.2MgSO₄ fertilizer. The Nutritional Balance Index (NBI) values were coherent with cotton yield, being the highest yields obtained with the smallest NBI in the covering fertilization with K₂SO₄.2MgSO₄.