should include macronutrients, such as nitrogen, phosphorus, sulfur, potassium and micronutrients such as boron, molybdenum and zinc.
Nitrogen (N): Grasses are heavy users of nitrogen. In order for irrigated pastures to stay healthy, vigorous and productive they need an adequate supply of nitrogen. The amount of nitrogen required depends on: 1. The density of the stand, 2. Species of forage plant, 3. Length of growing season and 4. Management.
Some management factors that will influence nitrogen needs are irrigation, grazing management, percentage of legumes in the pasture and if the legumes were inoculated.
In legume or grass-legume pastures containing 50 percent or more of a well nodulated legume, little or no fertilizer may need to be applied. With grass-legume pastures containing less than 50 percent legume, 60 to 150 pounds of actual nitrogen per acre will need to be applied. With legume mixes care must be taken to not apply more than 40 pounds of actual nitrogen at any one time, because it may inhibit the nitrogen-fixing bacteria in the nodules of the legume plants.
In poor stands, composed mostly of grass, applications up to 150 pounds of actual nitrogen per acre is advised. High yielding grass pastures may require 240- 320 pounds of actual nitrogen for maximum production.
Nitrogen is easily leached through the soil profile and beyond the pasture root zone. Ideally, nitrogen application should be divided into several (3-4) applications during the growing season. No one application should be more than 60 pounds of nitrogen per acre. Management to control over irrigation is important to prevent nitrogen leaching.
Phosphorus (P): Phosphorus is required by plants for strong root growth and meristem production. It is especially important in the establishment of new pastures, because it promotes early