Start Date: 2008
Principal Investigator: Daniel Kaiser
Organization: University of Minnesota, Department of Soil, Water, and Climate
Despite it being the single most important nutrient for wheat production, recent high costs of nitrogen (N) fertilizer have led many producers to question current N fertilizer management strategies, specifically the ability to maximize their return on investment. A need to reexamine current N rate guidelines and investigate new N fertilizer technologies, such as coated N products, was identified. This research provides scientific data and innovative approaches to N management for farmers already growing or interested in growing wheat in Minnesota.
Determine adequate N fertilizer needs of hard red spring wheat and winter wheat grown in Minnesota
Establish the efficacy of a split application of nitrogen for hard red winter wheat
Evaluate N uptake and utilization through the growing season of two spring wheat varieties, which vary in grain yield and protein of various combinations of straight and polycoated urea N sources applied in a single pre-plant application.
Nitrogen rate trials indicate that current N recommendations appear to be close to those found in the spring wheat studies. For spring wheat, applying N at a rate of 1.5 x the yield goal maximized yield but it took 2.0 to 2.5 times the yield goal to maximize protein production per acre.
For winter wheat studies, the data indicates less N was needed than recommended for spring wheat. Split applications would still be recommended for winter wheat with at least 30 lbs. of N applied in the fall as a starter and the remaining N applied in the spring. Applied N plus the amount of N in a 2’ soil test should equal 1.0 to 1.2 times yield goal.
The data comparing urea and polycoated urea showed inconclusive benefits for increasing wheat yields. Nitrogen accumulation trended less for polycoated urea (PCU), mainly due to the release characteristics from this product. The data showed that there was a benefit of polycoated urea for increasing protein, and this effect was greater with higher percentages of PCU versus urea. Zinc the release of nitrogen from PCU is related to soil temperature and moisture there is some risk of yield loss in dry or cool years.