Potassium Accumulation and Corn Yield Related to Potassium Fertilizer Rate and Placement

Sandy Coastal Plain soils have relatively low reserves of K and may not be able to supply adequate K for intensive corn ( Zea mays L.) production. Field experiments were conducted on Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudult) for 3 y to determine K fertilizer rate and placement effects on corn growth and seasonal K accumulation. Treatments were 0, 56, 112, 168, and 224 kg K ha ‐1 broadcast and 56 kg K ha ‐1 banded plus 0, 56, 112, and 168 kg K ha ‐1 broadcast. Total K accumulation was increased by K fertilization rate each year. Method of application had a significant effect in a relatively dry year when the broadcast‐plus‐banded treatments resulted in greater K accumulation. Stover dry matter was increased in two of three years with 56 kg K ha ‐1 , but grain yield was increased in only one year. Yield increased linearly with K rates up to 112 kg K ha ‐1 when the initial exchangeable‐K level was 0.21 cmol L ‐1 . Critical exchangeable‐K level was 0.35 cmol L ‐1 and the critical soil solution K concentration was 0.48 mmol L ‐1 for dry‐matter yield. When corn is grown with intensive production practices, there is little benefit in applying banded K with broadcast K on sandy soils testing high in K.