ARS | Publication request: Cycling and loss of nutrients in pastures

Submitted to: Progressive Forage Grower
Publication Type: Trade Journal
Publication Acceptance Date: March 14, 2012
Publication Date: May 15, 2012
Citation: Russelle, M.P. 2012. Cycling and loss of nutrients in pastures. Progressive Forage Grower. 5:18-19.

Technical Abstract: Pastures are fundamentally different than croplands. When cropland is harvested, large amounts of plant nutrients are removed so relatively large rates of nutrients are often needed. In pasture, most of the nutrients harvested by livestock are returned. The proportion of nutrients returned by livestock is directly related to the proportion of time the animals spend in pasture. The more time the animals spend around watering tanks, shade, and surface water, the higher the nutrient loading will be in those areas and the larger the pasture area will be that is nutrient short. Dairy cows excrete the vast majority of what they eat, but each element is voided in different proportions. The nutrient ‘application rate’ in urine spots and dung pats are quite high. As a result, we often see the crazy quilt pattern of rapidly growing spots and shorter, less vigorous pasture. One concern, of course, is that excess nutrients are more liable to be lost by volatilization, leaching, and runoff. To help prevent nutrient loss and to improve overall pasture productivity, animals need to be managed. Excreta distribution can be improved by moving watering sources, using portable shade, moving cross fences, and increasing stocking rate along with shortening the grazing intervals. Lack of vigor in desirable pasture plant species may indicate that one or more nutrients are lacking, or may be due to inadequate regrowth periods, droughty soils, strong preference by grazing animals, compaction, or other causes. Plant tissue testing and soil testing can help, but local guidelines should be followed. Remember that your profitability depends on efficient production of animal products, not just on forage yields. If you suspect or have evidence that one or more nutrients are lacking, try applying treatments in a few strips across the paddocks so you can observe effects on pasture growth and grazing behavior.