Effects of foilar applied K on California cotton

Abstract

Potassium deficiency symptoms become prevalent on leaves of many cotton varieties during the boll filling stage of growth. Soil applications of even large amounts of K are often not adequate due to fixation by vermiculite soils. A multi-year study was conducted to evaluate the response of California cotton (Gossypium hirsutum) varieties to foliar K applications. Rates of 10 kg K2O/ha were used employing potassium nitrate (KNO3), potassium sulfate (K2SO4), and potassium thiosulfate (K2S2O3). Potassium applied to the foliage about two weeks after the first bloom stage consistently gave positive yield responses. Yield responses ranged from 50 to 150 kg/ha over the untreated control, with no change in lint quality.