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Finding the right rangeland grass.

Someday, it may be possible to use a computer to select the best plant for any climate in any country, says ARS scientist Jerry R. Cox. "This could be a lifesaver for regions that barely have enough food for their populations today."

The computer program Cox talks about has yet to be developed, but he and scientists at Woodward, Oklahoma, are laying the groundwork. Cox obtained worldwide soil and climate data from the United Nations Educational, Scientific, and Cultural Organization (UNESCO) and is now using the information to locate areas that will support four particularly hardy grasses from Africa.

By using programs similar to the one that Cox is developing, people would enter soil and weather data from the geographic region they wish to plant. The computer would then match those conditions with information on plants that thrive under those conditions.

Candidate species could be further screened with the range plant profiles (RAPPS) computer model that is currently being developed by ARS researchers at Woodward.

The model uses weather and plant physiology data to simulate range grass growth. After comparing production and long-term survival, the scientists could recommend grasses with the highest probability of success.

As a range scientist, Cox has seen firsthand the need for better assurance that range seeding will succeed. He says the world's largest range experiment started around the beginning of this century because leaders in both the Northern and Southern Hemispheres were concerned about declining grassland productivity and increasing soil erosion.

Government employees and private individuals from Australia, England, South Africa, and the United States were enlisted in collecting and exchanging grass seed from every continent. The goal was to discover a "miracle grass" that would produce abundant forage with minimal water.

Hundreds of people planted thousands of seeds on their experiment stations and ranches. They noticed that four warm-season grasses native to Africa were easier to establish and persisted longer than grasses from other parts of the world. These four grasses, buffelgrass (Cenchrus ciliaris), weeping lovegrass (Eragrostis curvula), kleingrass (Panicum coloratum), and Lehmann lovegrass (Eragrostis lehmanniana), have dramatically increased productivity--at least, for a time---on millions of acres of depleted rangeland worldwide.

"For more than 100 years, there were thought to be only four steps to establishing perennial grasses on rangelands: clear shrubs from the land, prepare a seedbed, plant many varieties of seed, and pray for rain," says Cox at ARS' Forage and Range Research Unit in Logan, Utah.

But this simple set of rules produced a stand of grass in only 1 out of 10 attempts. Poor soils and scarce precipitation are formidable adversaries for tender grass seedlings.

Still, land managers kept trying in this crude way, because improved ranges were necessary to boost their profits. But in the 1970's, private land owners facing dramatically increased fuel prices could no longer afford to reseed 10 times in order to get one successful stand.

Cox says that between 1930 and 1986, scientists in many countries studied the four promising African grasses, but they did not attempt to create a database that would help explain why some grasses survived while others died.

"Because successes occurred infrequently, scientists and land managers tended to extrapolate prematurely whenever a species was successfully established. But often those preliminary successes could not be duplicated throughout a geographic region," says Cox.

For example, Lehmann lovegrass can be established on most soils in the southwestern United States and northern Mexico during a wet summer. However, the grass dies out during the next few years unless soils are either sandy or sandy loam and there are 6 to 9 inches of summer rain in 30 to 40 days," says Cox.

The initial establishment of plants from seeds was documented in 31 different countries for buffelgrass, 15 for weeping lovegrass, 9 for kleingrass, and 5 for Lehmann lovegrass. Today, buffelgrass survives only in six countries, weeping lovegrass in three, kleingrass in two, and Lehmann lovegrass in one.

Because each grass is self-perpetuating on two or more continents, Cox believes that some common factors directly affect plant establishment.

"If we can match soil and climate conditions where grasses evolved to potential new seeding sites with similar conditions, then range seeding in both the Northern and Southern Hemispheres may be more successful," says Cox.

To prove his theory, Cox collected climatic information and soil samples at more than 350 sites on five continents in 1986 and 1989. Countries he visited included: Argentina, Australia, Botswana, Brazil, Kenya, Mexico, Namibia, Pakistan, South Africa, and Tanzania.

Depending on various soil and climate factors, grasses either die, grow without spreading, or grow and expand onto an ever-increasing area.

Sometimes grasses that merely thrive are better suited to a site than those that spread out. For example, if land managers grow highly nutritious native grasses next to an area that needs reseeding, they will reseed with a grass that doesn't spread. Elsewhere, the area to be reseeded might be so vast that a spreading variety would be desirable to spare managers from having to seed every acre.

Cox recently introduced into southem Africa some 30 types of buffelgrass collected from around the world. "Our goal is to determine which ecotypes are best adapted to four cIimatic regions and then use genetic evaIuation to determine differences in pIant survival," Cox says. "If we can identify drought-tolerant genes and incorporate them into annual crops, we might be able to grow other grasses-- including wheat and corn--in areas of the world where today only range grasses survive." By Dennis Senft, ARS.

Jerry R. Cox is at the USDA-ARS Forage and Range Research Laboratory, Utah State University, Logan, UT 84322-6300. Phone (801) 750-3066. Four Exceptional Grasses

To survive and thrive, their requirements are as follows:

Buffelgrass: 6-20 inches summer rain, mean low winter temperature usually abouve 41 (deg) F. and loamy soil.

Weeping lovegrass: 16-40 inches of spring, summer, and fall rain; average winter temperature usually above 23 (deg)F; deep sandy soils.

Kleingrass: 16-39 inches of summer rain, average maximum daily summer temperature above 86(deg) average winter temperature usually above 32 (deg) and clay or silty soils. Weeping lovegrass and kleingrass spread to nonplanted sites only in Africa, where midsummer drought does not occur.

Lehmann lovegrass: summer rainfall exceeding 6 inches in 30 to 40 days and sandy or sandy loam soils. Predominates and spreads only in southern Africa, southeastern Arizona, and at few sites in northern Mexico.
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Title Annotation:includes related article on edible staple grasses
Author:Senft, Dennnis
Publication:Agricultural Research
Date:Jul 1, 1992
Words:1065
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