The 2000 growing season was the first year of a 5-year fertilization study. The study is being superimposed on the heavily grazed and moderately grazed pastures of the grazing intensity study by Bob Patton and Paul Nyren at the Central Grassland Research Extension Center. In North Dakota most range fertilization studies have used ammonium nitrate and super-phosphate fertilizers which are fast-release fertilizers. Northern Great Plains grasslands are dominated by cool season grasses. With fast-release fertilizers the cool season species are usually favored and warm season species usually decrease in species composition. When grazing animals harvest the forage each year they remove nitrogen and phosphorus from the system. Over the long term, productivity and species composition of the grassland can be affected. The objectives of this study are:
1. To determine the changes in species composition resulting from fertilization with slow-release phosphorus and urea on intensively grazed and moderately grazed mixed-grass prairie.
2. To determine the production of cool season grasses, warm season grasses, forbs and shrubs on the slow-release fertilizer treatments.
3. To determine the seasonal uptake of phosphorus in selected forage species.
4. To determine the soil phosphorus levels in different range sites or landscape positions of the Central Grasslands Research Extension Center.
Dr. William T. Barker
Animal and Range Sciences Department
North Dakota State University
Fargo, ND 58105