Strip-till, legume-cover crop system could help South Texas growers

BEEVILLE  —  Two years ago, when Dr. 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 said. “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, she said.

“I wondered why people were producing crops the way they were.”

After settling in at 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 the problems we are facing,” she said. “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.”

The price of nitrogen in fertilizers has increased as fuel prices have increased, Foster said.

“Phosphorous and potassium fertilizers also have their limitations,” she said. “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 said. “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 added.

“That would reduce the amount of moisture required to grow the legumes,” she said.

In conventional tillage, the entire field is tilled between crops; in strip tillage less than 70 percent of the field is tilled as growers leave behind 6- to 18-inch wide strips of untilled soil, Foster explained.

Growers in South Texas leave their fields completely bare and exposed during the off season for a couple of reasons, Foster said.

“It is easier to manage a tilled field, and other states have restrictions against conventional tillage,” she said. “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.”

This fall, Foster is starting legume research demonstration plots in Uvalde and Beeville to determine which perform best.

“We’ll do the research and develop data before making any recommendations,” she said. “Growers are not likely to change their practices until they know this strip-tillage, legume system will improve yields and increase profits.”

Foster said 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 said.

Foster said the 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 said. “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 said.

“Lots of problems, both environmental and financial are solved,” she said. “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 gasses and global warming. Plus, hay sales and grazing can increase incomes. That’s a lot of wins.”

Yet another plus could be that legumes break up insect pest cycles, Foster said.

“Dr. Mike Brewer, an entomologist at the Texas AgriLife Research and Extension Center in Corpus Christi, will be making observations,” she said. “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.”

Dr. Jamie Foster, a Texas AgriLife Research forage agronomist in Beeville, holds one of many legumes to be tested for use in South Texas. (AgriLife Research photo by Rod Santa Ana)

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