Effects of Variable Rate Potassium Application at Three Landscape Positions on Soybean Yield.

Effects of Variable Rate Potassium Application at Three Landscape Positions on Soybean Yield

A. Scholtz¹, D. Clay¹, C. Reese², S. Clay², T. Nleya², P. Sexton², J. Chang²

Department of Plant Science, South Dakota State University, Brookings, SD, USA

 

Precision farming provides an opportunity to vary fertilizers based on need.  The objective of this study was to determine the influence of landscape position on soybeans K response. The three landscape positions used were summit, backslope, and footslope.  At each landscape position, an experiment consisting of 3 blocks and three potash treatments were applied (0, 67.3, and 134.5 kg K2O/ha).   Soil samples were collected prior to potash application, and soybeans were harvested following physiological maturity.  In all cases, the soil K levels were above the 160 ppm level and the K response decreased with increasing EC value.   In the summit, backslope, and footslope positions, applying 67.3 kg K20/ha increased yield 150, -34.2, and 39.9 kg/ha, respectively.  For the 134.5 kg K2O/ha rate slightly different results and in the summit, backslope, and footslope areas K additions increased yields 163.8, 33.6, and -226.6 kg/ha, respectively.   When averaged across landscapes K did not influence yield.