Fertilizer Management for Seed Production of Perennial Forage
In the Canadian Prairie Provinces, nitrogen (N) and phosphorus (P) are most commonly deficient nutrients, while potassium (K) and sulphur (S) may also be deficient for certain crop and soil conditions. One or more of these four major nutrients may be limiting for optimum forage seed production. Nitrogen fertilizer application produces the greatest seed yield increase on grasses, but it will not increase seed yield if P, K, or S are limiting in the soil. The best N source for surface-broadcast application is ammonium nitrate, but it may not be widely available in the market.
Urea is now becoming the most commonly used N fertilizer, but urea and other ammonium-based fertilizers are highly vulnerable to N loss through ammonia volatilization when surface-applied thus diminishing the amount of N that may be available to the crop. So, time of application in relation to rainfall and placement method is important for ammonium-based fertilizers.