Fertilizing pastures can effectively increase forage production and rate of gain for stocker producers. But as fuel and fertilizer prices climb this year, producers need to look for ways to cut back and to get the most from the fertilizer they use.
A report from the Iowa Beef Center notes the price of nitrogen fertilizer is directly related to the price of natural gas, as it takes 33,500 cubic feet of natural gas to manufacture 1 ton of anhydrous ammonia fertilizer. Fuel prices, plus demand for high-value row crops will keep the price of nitrogen, as well as phosphorus and potassium, high this year.
Brian Peterson, state grassland conservationist with Iowa’s Natural Resources Conservation Service, suggests producers consider whether to spread high-priced commercial nitrogen every year or to incorporate more legumes into their pastures, such as red clover or alfalfa. Legumes produce nitrogen naturally, reducing the annual expense of purchasing fertilizer. Legumes also improve the quality of the forage and allow an extended grazing season.
Joe Sellers, a beef specialist with Iowa State University Extension, adds that another option is to use split applications of fertilizer rather than one large nitrogen application in the spring. He suggests producers consider how much grass will be added by using spring-applied nitrogen fertilizer and whether they have enough cattle to utilize all the increased production by summer. If not, they should consider split applications or interseeding legumes.
University of Nebraska Agronomist Bruce Anderson says Nebraska research shows about 1 pound of additional calf or yearling gain for every pound of nitrogen fertilizer applied, assuming applications within general recommendations and adequate moisture. This also assumes, he points out, that grazing management will efficiently harvest the extra growth. If you fertilize pasture in spring and then let animals graze continuously on one pasture throughout the season, he says, much of the extra growth is wasted. Cattle trample, foul and bed down on much of the grass and simply refuse to eat a significant percentage. Eventually, he says, cattle might actually consume less than one-third of the extra production.
To make fertilizer pay, he says, manage grazing so more of what you grow actually gets eaten. Subdivide pastures with some cross-fences and control when and where the animals graze. Give cattle access to no more than one-fourth of your pasture at a time, and preferably less, Anderson suggests. Allow them to graze off about one-half of the growth before moving to another subdivision.
If your pastures aren’t already subdivided into at least four paddocks, he says, your fertilizer dollar might be better spent on developing more cross-fences and watering sites.