Potassium dynamics in cotton with a white clover living mulch: A Georgia Piedmont case study

Cover crop utilization is an important strategy for improving row crop sustainability and plays a critical role in managing plant–soil nutrient relations needed to maintain cotton (Gossypium hirsutum L.) yields in the southeastern United States. Most cover crops are annual species, but perennial cover crops, sometimes called “living mulches” (LMs), can provide year-round benefits. The effects of LM on nitrogen and carbon dynamics have been explored in corn systems. However, information on these dynamics and effects on other nutrients are limited in cotton systems. This project quantified the effect of a white clover LM on nutrient cycling of macro- and micronutrients (excluding N) in a cotton production system in the Georgia Piedmont. This included soil, plant, and pore water samples collected at important cotton reproductive states for 2 site-years with different soil fertility. Additional samples were taken between cotton growing seasons to evaluate soil–clover interactions. Nutrient responses in the system (specifically K) were connected to soil test levels for nutrients at the start of reproduction. Only when the soil had above optimum K levels (2021), the LM luxury consumed excess K from the soil. Cotton leaves had the greatest fluctuations in K concentrations when LM was present from pinhead to cutout when soil K was below optimum. In winter, the soil had the greatest K concentration in treatments with the most clover relative to bare ground. Using optimal LM coverage can prevent excess K from potentially being lost from the system while not affecting cotton leaf K nutrition during reproductive growth.