With nitrogen fertilizer costing 60¢ or more per pound, fertilizing continuously grazed pastures this spring might not be profitable, warns Bruce Anderson, University of Nebraska Extension forage specialist.
Nebraska research shows that every pound of nitrogen fertilizer applied stimulates enough added grass growth for about 1 lb of additional calf or yearling gain. But that thumb rule assumes that recommended amounts are applied and that the animals will efficiently harvest the 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,” says Anderson. “They trample, manure and foul, bed down on, and simply refuse to eat much of the stemmy grass. Eventually, less than one-third of the extra grass ends up inside your livestock.”
To make fertilizer pay, manage grazing so more of what you grow actually gets eaten, he advises. Subdivide pastures with cross fences and give the animals access to no more than one-fourth of each pasture at a time, preferably less. Then graze off about half of the growth before moving to another subdivision. Maybe even save one subdivision for hay.
“If your pastures aren’t subdivided into at least four paddocks, fertilizer dollars might be better spent on developing more cross fences and watering sites,” says Anderson.
He also suggests saving some of the fertilizer until later in the season, when more grass often is needed. Fertilize half to three-fourths of your pasture this spring, then graze normally, but be sure to finish grazing the unfertilized area by mid-May. Then fertilize that area if it looks like there will be enough moisture for grass growth, and you’ll have some good regrowth for grazing in July or August. If it’s dry in mid-May, save your money and don’t apply more fertilizer.
“If your pastures are overgrown in spring and run out in summer every year, change fertilizer timing,” Anderson says. “You’ll get more grass when you want it or maybe save some money.”