Current UWEX fertilizer recommendations and plant analysis interpretation guidelines were developed prior to the release of GMO corn. There is some concern amongst University soil fertility specialists and industry agronomists that corn and soybean response to P and K fertilizer applications may be different with modern corn hybrids and soybean varieties. In addition, in the UW recommendation system, an estimate of the amount of nutrients removed in the harvested portion of the crop is used to determine the fertilizer recommendations based on soil test levels (Laboski and Peters, 2012). If crop removal rates have changed in modern hybrids is it essential to determine current removal rates and use those numbers in fertilizer recommendations.
Soil Science Extension
University of Wisconsin Madison