Legume cover crop, strip till could help South Texas fields
Two years ago when Jamie Foster was moving from Florida to become a Texas AgriLife Research forage agronomist in South Texas, her job almost hit her in the face — literally.
“When I first moved here, I was driving between Mathis and Skidmore [near Corpus Christi],” Foster recalls. “The wind was blowing, and topsoil was hitting my car.”
She thought of the 500 years it takes for the earth to produce 1 inch of topsoil. “I wondered why people were producing crops the way they were.”
But after settling in her job at the Texas AgriLife Research Station in Beeville, Foster learned that for lots of reasons, conventional tillage was the preferred method of producing crops.
“I thought that incorporating strip-tillage with a legume cover crop in the winter might be a good solution to a lot of problems we are facing,” she says. “Here in South Texas, those problems are primarily moisture availability because of the drought situations and low rainfall in general, and also rising fertilizer prices.
• Strip tillage, legume cover crop could help with moisture loss and fertilizer needs.
• Legumes have the potential to hold the soil on windy days.
• Moisture loss and nitrogen loss can be reduced with this system.
The price of nitrogen fertilizers has increased as fuel prices have increased, Foster notes.
“Phosphorus and potassium fertilizers also have their limitations,” she says. “They are limited resources, and we’re competing with India and China more and more every day for these other two primary resources.”
Foster is now working to identify legumes adapted to growing conditions in South Texas, including medics and clover, which have the potential to serve as cover crops.
“As off-season cover crops, the legumes have the potential to hold the soil in place on windy days and also improve the nitrogen cycling and availability,” she says. “Legumes do take a lot of phosphorus to grow, but as they degrade in the soil, they leave some behind that’s available for the row crops that follow its production, be it cotton or sorghum.”
As the cool-season legumes grow, they can be harvested periodically for hay for added income, or even grazed, she adds.
“That would reduce the amount of moisture required to grow the legumes,” Foster says.
In conventional tillage, the entire field is tilled between crops; in strip tillage less than 70% of the field is tilled as growers leave behind 6- to 18-inch-wide strips of untilled soil, she says.
Foster says growers in South Texas traditionally have left their fields completely bare and exposed during the off season for several reasons.
“It is easier to manage a tilled field, and other states have restrictions against conventional tillage,” she says. “Or they offer incentives to not till a field completely to reduce runoff. And there’s a perception that a clean field is a better, neater field.”
Test for best
Foster has just started legume research demonstration plots in Uvalde and Beeville to determine which perform best.
“We’ll do research and develop data before making any recommendations,” she says. “Growers are not likely to change their practices until they know this strip-tillage, legume system will improve yields and increase profits.”
Foster says the research will be relevant to a large swatch of South Texas — a line from Victoria to San Antonio to Yoakum.
“Our research project will start with 1 acre of legumes at each of our two sites in Beeville and Uvalde; then we’ll scale that up after a crop rotation cycle when we find a few legumes that will work,” she says.
Times are changing
Foster says changing economic times are making a strip-tillage with legume cover crop system more attractive to growers.
“When fertilizer and fuels were relatively cheap and moisture was abundant, it was easy to continue with conventional tillage, or no-till,” she says. “But with those prices rising so dramatically, so is interest in this new system. Strip-till equipment is available, and there are now modern legume cultivars to choose from.”
The advantages of switching are just too enticing to ignore, Foster says.“Lots of problems, both environmental and financial, are solved,” she adds. “It reduces erosion, soil moisture loss and nitrogen loss. It improves organic matter in soil, which means the soil is holding carbon. That reduces carbon emissions, greenhouse gases and global warming. Plus, hay sales and grazing can increase incomes. That’s a lot of wins.”
Foster says yet another plus could be that legumes break up insect pest cycles.
“Dr. Mike Brewer, an entomologist at the Texas AgriLife Research and Extension Center in Corpus Christi, will be making observations,” she says. “Planting the same crops year after year, even in a cotton-sorghum rotation, tends to attract insects and promote continuous breeding cycles. Insects may not be interested if we introduce legumes.”
Santa Ana is with Texas A&M Agriculture Communications.
This article published in the January, 2012 edition of THE FARMER-STOCKMAN.