Effects of Potassium Rates and Timing on Cotton Yield and Fiber Quality

Ensuring potassium (K) is readily available for plant uptake during all stages of growth, especially during reproductive growth, is critical for cotton production. While improvements in cotton genetics and production have led to significant yield improvements, observations of K deficiencies are still common. Re-evaluating the current cotton K fertility recommendations is necessary. The objective of this research was to predict the effect of variable timings and rates of K on cotton yield and fiber quality. Field trials in North Carolina were conducted at two locations in 2017 and three locations in 2018. Treatments included three rates (1, 1.5, and 2 times the soil test analysis recommended rate) applied using three timing combinations (planting, planting and layby, and planting, layby, and three wk after layby) compared to a non-treated control. Layby applications occurred between 45 and 62 d after planting. Treatments were applied as a broadcast granular and the source was muriate of potash. Growth and maturity measurements were recorded throughout the growing season. Petiole samples were collected at five weeks after layby for analysis of K concentration. Yield and fiber quality were also measured. Neither K rate nor application timing had a significant effect on lint yield and fiber quality in any environment. The concentration of tissue K did respond positively to K rates and timings in soil with low potassium availability.