Texas Crop Weather

Forage scientist: Bermuda grass pasture stands can be very sustainable without nitrogen

The purple-colored patches on the right side of the fence are signs of invasion of common Bermuda grass into Coastal Bermuda grass pasture under a high stocking rate, according to a Texas A&M AgriLife Research forage scientist. On the left side of the fence, the stocking rate was medium and shows much less invasion of common ecotypes. The pastures on both side of the fence received nitrogen fertilizer at usual rates during a 30-year study of the effects of stocking rates and nitrogen rates on pastures. (Texas A&M AgriLife Research photo by Dr. Monte Rouquette)

Writer: Robert Burns, 903-834-6191, rd-burns@tamu.edu

OVERTON In an East Texas study on sandy, low-fertility soils, Bermuda grass pastures that have not received nitrogen fertilizer since the fall of 1984 are still in production, according to Dr. Monte Rouquette, Texas A&M AgriLife Research forage physiologist, Overton.

The study, which originally began in 1968 on pasture-research areas at the Texas A&M AgriLife Research and Extension Center at Overton, has been conducted by Rouquette since 1971.

The original purpose of the study was to evaluate various forage varieties for production and persistence using cow/calf pairs with different stocking rates, he said.

The original perception was that this might be a five-year study, Rouquette said. But after five years, reality set in, and I realized it was necessary to extend the time period.

By 1984, rising fossil fuel costs, and along with them, much higher nitrogen fertilizer costs, became a game-changer for beef producers. Rouquette responded by redirecting the grazing study to evaluate the persistence of both common and Coastal Bermuda grass under two different fertility-management strategies: over-seeding with ryegrass and using commercial nitrogen fertilizer; and over-seeding with clover without applying nitrogen.

I thought that this would be a good time to initiate a nutrient cycling experiment wherein pastures could be treated with nitrogen fertilization and over-seeded with ryegrass versus no nitrogen and over-seeded with clovers for nitrogen fixation, he said.

Rouquette noted that in 1984, all the test pastures had adequate levels of potassium and phosphorus. As the study proceeded, all test pastures received potassium and phosphorus fertilizer yearly in the form of 0-60-60. Lime was applied as needed.

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Texas Crop Weather