The effect of foliar applied KNO3, compared to soil applied KCl, on cotton yield was evaluated in a three year Beltwide study. The yields were averaged over sites for foliar potassium studies in 12 Cotton Belt states in the USA. In the low soil K treatments potassium was applied as KCl according to preplant soil tests and for the high soil K treatments this recommended dose was doubled. Foliar rate was 11,2 kg/ha/spray of KNO3 applied four times at 10 to 14 day intervals after first flower. All treatments showed yield increases compared to the control (Figure 1).
Figure 1. Mean cotton yield increases averaged over 12 Cotton Belt states.
Oosterhuis, D.M. 1994. Foliar fertilization of K on cotton shows potential. Fluid Journal. Summer 1994. P. 1-2.