Previous Corn Row Effects on Potassium Nutrition and Yield of Subsequent No-Till Soybeans

Narrow-row soybean [Glycine max (L.) Merr.] production in corn [Zea mays L.]–soybean rotations results in various distances of soybean rows from previous corn rows, yet little is known about soybean responses to proximity to prior corn rows in no-till systems. The objective of this study was to evaluate the impacts of preceding corn rows on potassium (K) nutrition and yield of subsequent no-till soybeans. Four field experiments involving a corn–soybean rotation were conducted on long-term no-till fields with low to medium K levels from 1998 to 2000 near Paris and Kirkton, Ontario, Canada. In the corn year, treatments included K application rate and placement in conjunction with tillage systems or corn hybrids. Before soybean flowering, soil exchangeable K concentrations (0–20 cm depth) in previous corn *Correspondence: Tony J. Vyn, Department of Agronomy, Purdue University, West Lafayette, IN 47907-1150, USA; E-mail: [email protected]. JOURNAL OF PLANT NUTRITION Vol. 26, No. 7, pp. 1383–1402, 2003 DOI: 10.1081=PLN-120021049 0190-4167 (Print); 1532-4087 (Online) Copyright # 2003 by Marcel Dekker, Inc. www.dekker.com 1383 rows were significantly higher than those between corn rows. At the initial flowering stage, trifoliate leaf K concentrations of soybeans in preceding corn rows were 2.0 to 5.3 g kg 1 higher than those from corresponding plants between corn rows. Yield of no-till soybeans in previous corn rows increased 10 to 44% compared to those between previous corn rows. Positive impacts of prior corn rows on soil K fertility, soybean leaf K, and soybean yield occurred even when K fertilizer was not applied in the prior corn season. Deep banding of K fertilizer tended to accentuate row vs. between-row effects on soybean leaf K concentrations in low-testing soils. Corn row effects on soybeans were generally not affected by either tillage system or corn hybrid employed in the prior corn crop. Potassium management strategies for narrow-row no-till soybeans should take the potential preceding corn row impacts on soil K distribution into account; adjustments to current soil sampling protocols may be warranted when narrow-row no-till soybeans follow corn on soils with low to medium levels of exchangeable K.