Knowledge of potassium (K) requirements for cotton growth and development is needed for efficient production. Fertilization of cotton with K is a complex issue, because soils vary widely in terms of K-supplying capacity and K fertilizer adsorption.
Growth processes are limited when leaf K concentrations are below 2%, and visual symptoms of K deficiencies are difficult to identify. Critical foliar K concentration required for optimum photosynthesis,  and  thus  the  productivity  of  cotton  (95%  of  the maximum), is 2.1%. Several processes are severely affected below that critical foliar K level.