AMARILLO -- Ground left fallow in the High Plains to store soilmoisture between crops may be better off with a legume crop such ascowpeas, according to a Texas Agricultural Experiment Stationresearcher.
Dr. Bill Payne of Amarillo said he is trying to make the region'swheat-sorghum-fallow cropping system more sustainable by getting rid ofthe fallow component.
Leaving the land idle for one cropping season is a way toretain soil moisture for the following crop. However, Payne said, thispractice doesn't store that much moisture. And it oxidizes the soilorganic matter, leaving the land subject to erosion and releasingcarbon into the air, thereby contributing to global warming.
Planting a legume crop, such as cowpeas, allows the producerthree crops in three seasons, rather than two crops in three seasons,he said. The residue from the cowpeas also adds organic matter, whichtends to decompose faster than cereal crop residue, Payne said.
"What we'd like to do is plant it the year after sorghum andbefore fall-planted wheat," he said. "What we're trying to do now isfind the right maturity group among cowpea varieties."
Cowpeas can be grown in as little as 65 days, allowing for abrief fallow period before the wheat is planted. A longer-seasonvariety can go until a killing frost, Payne said. The research is aimedat finding a balance between biomass production and water conservation,he said.
"The options would be to hay it or graze it as a forage, or ifthere's a market for the peas, a producer could go for that," Paynesaid.
The crop can be harvested at flowering for forage and at peaproduction, as with blackeyed peas. By doing both, he can compare waterusage and determine potential water stress on the next crop.
"Our hope is the wheat yields will increase following cowpeas,as well as the sorghum," Payne said. "We see that in other parts of theworld, but here we have to be careful of the water component."
Preliminary data shows the more cowpea biomass produced, thelarger the yield increase of the following cereal crop, he said.However, the study must run for at least six years or two entire croprotations to confirm the results.
Determining the sustainability characteristics -- changes tothe soil physical and chemical properties -- will take even longer, hesaid.
"We can show now that growing cowpeas results in less soilwater storage at wheat planting than fallowing," Payne said. "But sofar, it has been such a small amount, it's insignificant as far asyield goes."
Cowpeas' water requirements depend on the maturity group, butthe goal is to find a variety that will survive on 12 inches ofrainfall, he said.
During 2003's dry growing season, Payne said, the sorghum diedoff before the cowpeas, which means cowpeas is a very drought tolerantcrop.
Payne said some experts are concerned that cowpeas grown onany significant scale in the U.S. would flood the human consumptionmarket and lower the price. However, as forage, cowpeas shows a lot ofpotential, he said.
In Africa, tests show cattle's weight gain doubles when cowpea fodder is added to their diet, Payne said.
"I think producers are looking for a high-protein forage crop,"he said. "There's a reason cowpeas are called 'cow' pea. Earlier on,cows grazed it throughout the South."
The protein value of cowpeas ranges from 22 percent to 30 percent, Payne said.
"We'll have to work with producers and (Texas Cooperative)Extension agents to see how it works into a production system," hesaid. "Timing of pasture availability will be important. We want to tryto time its availability with the greatest demand, so there are stillthings to work out."
Materials provided by Texas A&M University - Agricultural Communications. Note: Content may be edited for style and length.
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