OVERTON — There is a way to beat high nitrogen fertilizer costs for pastures when it comes to putting pounds on calves.

This according to a four-year study comparing different pasture management systems with cows and calves by the Texas Agricultural Experiment Station.

Based on average daily gain of calves, the study found that adding a cool-season clover to a warm-season perennial grass was more profitable than applying high amounts of nitrogen.

"Adding a cool-season clover to a warm-season perennial grass was more profitable than the high- and no-input systems because the clover extended the grazing season, had higher nutritive value, and provided summer weed control in addition to adding N (nitrogen) to the pasture system," wrote Dr. Gerald Evers, Experiment Station researcher in his formal report.

Evers compared three systems:

— A high-input system on Dallis grass pastures using 150 pounds of nitrogen per acre and herbicides for weed control.

— A medium-input Dallis grass system where winter clover was over-seeded into a stand of warm-season grass pasture.

— A no-input pasture system, using no nitrogen, no herbicide and no clover.

Evers, who is now based at the Texas A&M University System Agricultural Research and Extension Center at Overton, originally conducted the study at a site near Angleton in the 1980s. At that time, however, nitrogen fertilizer was relatively cheap, he said. And other than summer weed control, the economic benefits to using a cool-season clovers were not clear.

With nitrogen costs topping 55 cents per pound in 2007, that situation has changed, Evers said.

Average daily gains for the calves were 1.57, 1.82 and 1.66 pounds per day for the high-, medium- and no-input systems.

"Using 2007 costs for pasture and animal inputs, production costs per pound of calf gain were $1.12, $0.58, and $0.81 for the high-, medium- and no-input pasture systems respectively," Evers wrote.

Additionally, using clover in the medium input system proved "as effective as applying herbicide in April for controlling summer weeds" in the high-input system, he said.

"Average daily gain for the cows on the clover-grass system was even higher, being twice that of the other two grass-only systems because of the longer grazing season and higher nutritive value of the clover," Evers said.

The original study was using Dallis grass and white clover, both of which are well adapted to the upper Texas Gulf Coast region. The system is just as applicable to more northern regions of Texas, though different grasses and legumes would need be used, he said. North of Interstate 10, soils are sandier and better drained. Bahia grass and Bermuda grass are better adapted to these areas than Dallis grass or white clover, he said. As for the clover component, arrowleaf, crimson and ball clovers are better adapted.

"Instead of only planting pure clover, I would mix annual ryegrass with that clover," Evers said. "If you mix rye grass with the clover you don't worry about bloat. In that (Angelton) study, we had to feed bloat guard blocks for six weeks when most available forage out there was white clover so you could eliminate that expense of having to buy bloat guard blocks by just putting annual rye grass with the clover.

"By adding clover we started grazing five weeks earlier than if we didn't have clover, so that helped us by about $60 per cow," Evers said. "So if you add ryegrass to the clover we could even start grazing another four to five weeks earlier than when we started grazing clover, and that would give you another $50-$60 in winter feed cost savings per cow."

The one issue many East Texas producers must attend to before they rush into over-seeding clover this fall is soil acidity, Evers cautioned. Raising soil pH by liming takes four to six months. Unamended East Texas soils often have a soil pH of 5.5 or lower.

"You like to see the pH at 6 or higher, but now here we are the early part of August," he said.

"If they do a soil test and the pH is 5.5, they could put on 2 tons of lime and raise the pH some by fall. It might not reach a pH of 6 in two to three months, but it would be closer to 6 than 5.5."

Though producers might not see optimum clover production until spring, they could still get could results.

"The only thing you worry about if the soil is real acid in the fall when you plant is you may not get a good stand of clover," he said.

Since 1970, Evers has worked on forage production problems throughout the eastern half of Texas. He is the primary author or co-author of papers presented at the International Grassland Congress in Kentucky, France, New Zealand, Canada, and Brazil and the International Herbage Seed Conference in Oregon, East Germany, Italy and Australia.