Making pasture fertilizer pay for itself depends on not only getting added forage production, but getting the added pounds into cattle.
“Our Nebraska research shows that you get 1 lb. of additional calf or yearling gain for every 1 lb. of nitrogen fertilizer applied,” says Bruce Anderson, University of Nebraska Extension forage specialist. “However, this fertilization rule-of-thumb assumes that the amount applied is within our general recommendations, which are based on the potential amount of extra grass growth expected. This is affected mostly by moisture. It also assumes that your grazing management will efficiently harvest this extra growth.
“If you fertilize pasture in spring and then let animals graze continuously on one pasture throughout the season, much of the extra growth is wasted. They trample, manure and foul, bed down on, and simply refuse to eat much of the grass. Eventually, less than one-third of the extra grass ends up inside your livestock.”
That’s where rotational grazing comes in. Anderson suggests giving cattle access to no more than 25% of a pasture at one time.
“Then graze off about one-half of the growth before moving to another subdivision,” Anderson says. “If your pastures aren’t already subdivided into at least four paddocks, your fertilizer dollar might be better spent on developing more cross-fences and watering sites.”