Fertilization of Warm Season Annual Grasses

Summer annual forages must be fertilized to reach their yield potential. As with all crops, fertilization and lime application should be done according to recommendations based on the results of a soil test. Warm season annual grasses generally perform well on sites with soil pH values around 6.0 or higher. However, pearl millet is less sensitive to soil acidity than the sorghums. Nitrogen is needed in large quantities and is most often the least limiting nutrient. When used for grazing, apply 40 – 60 lbs of N per acre for establishment and 50 – 60 lbs of N per acre each month during the grazing season. When harvested for hay or silage, apply 40 lbs of N per acre at planting and 40 – 60 lbs of N per acre after the first two cuttings. Reduce N rates after the crop growth rate slows down. Summer annuals grown under irrigation should receive N rates on the upper end of these ranges.

Dr. Dennis Hancock
Forage Extension Specialist
Crop & Soil Sciences Dept.