Residual Effects of Potassium to Cotton on Corn Productivity under No‐Tillage

The long‐term residual effects of K applications to preceding cotton (Gossypium hirsutum L.) on subsequent corn (Zea mays L.) is largely unknown under no‐tillage. A cotton field experiment was conducted on a no‐tilled Loring silt loam (fine‐silty, mixed, active, thermic Oxyaquic Fragiudalf) at Jackson, TN, during 1995 to 2008 with the K treatments of 0, 28, 56, 84, 112, 140, and 168 kg ha−1applied to the same plots each year. From 2009 through 2011, corn was no‐till planted on the previous cotton trial without further K fertilization. Incremental gains in corn leaf K responses were consistent with increases in the K application rate for previous cotton. A significant quadratic relationship was observed between corn yields and K application rates in 2010 and 2011 with corn yield peaking at the K rate of 94 kg ha−1 in 2010 and 84 kg ha−1 in 2011. Potassium removal by grain ranged from 2.54 to 3.55 kg K Mg−1 of grain yield. For the 28 kg K ha−1 rate and those higher K rates, soil K buffering capacity followed an exponential decline as the initial soil test K level increased. Surface broadcasting of K fertilizer at the recommended rate of 56 kg K ha−1 or above to preceding cotton for 14 yr and relying on the residual K fertilizer for the subsequent corn for at least 3 yr without further K fertilization might be a viable K management practice on high K fields under no‐tillage.