If the midseason PSNT shows low N levels, make a sidedress fertilizer application. Corn plants begin their greatest uptake of nitrogen around the 5-leaf stage, or when the plants are about 12 inches tall at the center of the whorl. A PSNT value of 25 ppm or greater is sufficient for maximum silage corn yields. If the PSNT value is below 25 ppm, apply nitrogen at the rates shown in Table 1. Nitrogen can be supplied by manure or commercial fertilizer.
Most dairies produce enough manure to supply needed N, making fertilizer purchases unnecessary.
See EM 8585, Manure Application Rates for Forage Production , for more information. Excess nitrogen will not be used by the crop and will remain in the soil after harvest. During winter, rain may wash nitrate from the soil into surface and ground waters. This poses a threat to human and environmental health and wastes fertilizer dollars. If you want to print this publication, we recommend downloading the PDF version.