In Press: Alfalfa shows potential as a low-water input crop, protein bank
By: Norman Martin
Recently, Chuck West, the Thornton Distinguished Chair with Texas Tech University's Department of Plant and Soil Science, spoke with the High Plains Journal's Lacey Newlin about some of his latest research on alfalfa. West is part of a research team to bring home first place honors with this year's Crop Science Outstanding Paper Award for the Forage and Grazinglands Division of the Crop Science Society of America.
Alfalfa is native to semi-arid southwest Asia, and countries such as Iran, Georgia and Afghanistan, where it has developed under very hot, dry conditions. Although much of it is irrigated, it also grows on rangeland as well, and it can be successful in the dry areas of the United States with help from grass varieties.
"Our overall aim is to help producers in the Texas High Plains and elsewhere, transition toward lower water use by integrating grazing into cropping systems so it's not just all cotton or all corn," said Chuck West, the Thornton Distinguished Chair with Texas Tech University's Department of Plant and Soil Science. "We're all aware of the water supply declining in the Ogallala Aquifer. My work is in low-cost pasture production and improving the nutrient quality of pastures, with a particular interest in tracking the amount of water it takes to grow the forage. Alfalfa is famous for being a high-water using crop, but my emphasis is on grazing alfalfa in mixture with grasses. We want to take advantage of two fantastic traits alfalfa has, one is that it fixes its own nitrogen thanks to special bacteria growing in the roots, and the other is that it has a high nutritive value."
The conventional use of alfalfa is as a highly irrigated, high water use, multiple cuttings crop for dairy farms and to sell as a hay commodity. However, West sees alfalfa's potential as a low-water input crop, used as a protein bank for grazing and mixed with perennial grasses. A protein bank is a small acreage of high-protein forage for limit-grazing in rotation with a large acreage of low-protein forage. Rye and wheat are widely grown across the southern Plains either separately or next to winter-dormant, warm-season grasses. Limit-grazing of high-protein forage works well while the cattle also have a stockpile of lower-protein bermudagrass or Old World bluestem.
West said the main warm-season perennial grass that he uses with alfalfa is a type of Old World bluestem grass called WW-B. Dahl. It is a low-water use grass that is late flowering in July or early August, which is a big advantage over the native warm season grasses that flower early and become stemmy. "This means it stays leafy during June and July and we can get some very good grazing out of it," West said. "It supports average daily gains of anywhere from 1 to 2.5 pounds per day. Typically it's more like 2.5 in the May, June and early July months, then it drops down to about a pound to a pound and a half later in the season."
West said in an alfalfa and grass pasture mixture with no nitrogen applied, cattle experienced 2.1 average daily gains over four months and protein content was double with the mixture. In a grass-only system with 60 pounds of applied nitrogen fertilizer, cattle experienced 1.7 pounds of average daily gain. Both systems received similar amounts of water.
"For steers to gain weight, we need a protein content of at least 12.5%, so the grass-only cattle were protein deficient because the grass was only 7% protein," West said. "As for water use per pound of cattle weight gain, the alfalfa and grass mixture took 364 gallons per pound of gain versus 501 for the grass-only system. So it took 27% less water to produce a pound of gain when we had a legume compared to grass only," West said. High-quality alfalfa made all other inputs more efficient. Plus, no nitrogen fertilizer was applied to the alfalfa system.
"Alfalfa is the best legume option in low-input irrigated stocker pastures in the Texas High Plains when grown as a minority component with grasses," West said. "A persistent hay-type alfalfa has potential in dryland and very low irrigated pastures on good water-holding soils. Use alfalfa on good soils where you can manage to avoid overgrazing. Even as a minor component of the pastures, alfalfa significantly improves forage quality with only minimal changes in water use."
CONTACT: Chuck West, Thornton Distinguished Chair, Department of Plant and Soil Science, College of Agricultural Sciences and Natural Resources, Texas Tech University at (806) 834-4160 or email@example.com
0917NM20 /Editor's Note: For the full-text version of Lacey Newlin's article in the High Plains Journal, please click here
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