Michigan State University Extension
Soils & Soil Management - Fertilizer - 06109716
07/10/97
Nutrient Management to Protect Water Quality Extension Bulletin WQ-25, January 1996
Maurice L. Vitosh and Lee W. Jacobs Extension Soil Specialists Department of Crop and Soil Sciences Michigan State University
Plant analysis during the season offers the grower an opportunity to assess the status of nutrients in the growing plant. High or excessive levels of a nutrient in the plant tissue are an indication that more nutrients may have been applied than were necessary for optimum growth. Once the fertilizer or manure has been applied, little can be done, but N rates can be reduced in future years to bring the nutrient levels back into the normal or sufficiency range.
Research on corn is being conducted to determine if tissue chlorophyll meter readings or plant analysis for N during the growing season can be used to help determine the amount of N to apply. Once the corn plant is past the sidedress stage, however, growers may encounter other difficulties in applying N fertilizer. The only equipment available for non-irrigators is high-clearance equipment and aerial applicators. In addition, N applied at later stages may not be beneficial. Research indicates that N applied to corn after silking is not efficiently utilized.