Michigan State University Extension
Soils & Soil Management - Fertilizer - 06029711
07/10/97
Fertilizer Recommendations for Field Crops in Michigan Extension Bulletin E-550A, March 1992
D. R. Christenson, D. D. Warncke, M. L. Vitosh, L. W. Jacobs and J. G. Dahl, Department of Crop and Soil Sciences
Corn and Corn Silage, Sorghum and Sudangrass
Corn-Place planting-time fertilizer 2 inches to the side and 2 inches below the seed. At this placement the fertilizer application may include up to 40 pounds of nitrogen and 100 pounds of potash per acre and all the recommended phosphorus. Including phosphorus in the row fertilizer when the available soil phosphorus is high may stimulate early season growth, but seldom increases the corn yield. Plow down or broadcast and incorporate any phosphorus and potassium fertilizer that is required in excess of that banded at planting.
Irrigation of corn influences the fertilizer requirements because it increases the yield goal. These requirements are accounted for by larger yield goals. Nitrogen management will need to be adjusted and part of the nitrogen will need to be applied either sidedressed or through the irrigation system. One management system suggests to apply one-third preplant, one-third sidedressed and the remainder applied through the irrigation system.
Harvesting corn for silage removes large amounts of plant nutrients. In a Michigan study, corn yielding 140 bushels of grain removed 120 pounds of nitrogen, 52 pounds of phosphate and 27 pounds of potash per acre. The same crop harvested for silage removed 196 pounds of nitrogen, 69 pounds of phosphate and 206 pounds of potash per acre. This comparison illustrates that nutrient removal, especially of potash, is much greater when silage is harvested. Recommendations for phosphorus and potassium are adjusted for this additional removal.
Nitrogen management for corn may involve a choice of application times: preplant, planting time and/or sidedress. Applying nitrogen in the fall is not recommended. Nitrogen applied as a sidedress will generally be used most efficiently.
MINERAL SOILS-Nitrogen recommendations for corn are given in (Vis. 8). Phosphate and potash recommendations for corn are given in (Vis. 9).
ORGANIC SOILS-Nitrogen recommendations for corn are given in (Vis. 16), phosphate in (Vis. 17), and potash in (Vis. 18).
Sorghum and Sudan grass-Sorghum and Sudangrass grown for summer pasture or chopped forage have nutrient requirements similar to those of corn silage. Use the equations for corn silage and the appropriate yield goal in (Vis. 8), (Vis. 9) for mineral soils. On organic soils, use recommendations in (Vis. 16), (Vis. 17), (Vis. 18).
