A continuing study of cover crops in the Rolling Plains has determined that yes, they do use water, but that does not necessarily translate into reduced cash crop performance. There has been much interest nationwide about cover crops and the effects they have on soil health. Those beneficial effects are exactly what he being seen in multiple studies, although none are immediate.
According to Dr. Paul DeLaune, an AgriLife Research environmental soil scientist, the No. 1 question farmers have is “if I plant a cover crop, how much soil moisture is it using, and what are the benefits of having a cover crop compared to standard no-till without a cover crop?”
DeLaune said he has worked on two studies using cover crops in the Rolling Plains: warm-season cover crops in dual-use wheat – for cattle grazing and grain production – systems and cool-season cover crops in cotton cropping systems.
In both studies funded by the U.S. Department of Agriculture-Natural Resources Conservation Service, DeLaune is examining conventional tillage without cover crops; no-till without cover crops and no-till with various mixtures of cover crops.
Examining the impact of cover crop implementation in long-term no-till wheat systems was initiated in June 2013 near Vernon. The demonstration has been on no-till for 12 years. Treatments include standard no-till and conventional till treatments, no-till with a multi-species cover crop and no-till wheat intercropped with turnips and radishes.
The multi-species cover crop consisted of sorghum sudan, millets, peas, forage soybeans, sesame, lablab and buckwheat. This mix was seeded in early June at 30 pounds per acre, at a total seed cost of nearly $33 per acre. Radishes and turnips, planted at a half-pound per acre each, were mixed with wheat at planting in early October for intercropped treatments.
“With the financial investment associated with cover crops, there is an interest in knowing what the return investment is,” DeLaune said. “This is one reason we are evaluating grazing opportunities provided by cover crops. Cover crops could provide supplemental grazing opportunities as well as stimulate soil biology by incorporating residue in to the soil through trampling and addition of organic matter through defecation during the grazing period.”
As seen with cool-season cover crops in cotton systems, stored soil moisture was significantly lower at the time of wheat planting in treatments consisting of cover crops compared to standard no-till and conventional till treatments without the multi-species cover crop.
“It will be interesting to see how stored soil moisture responds after a major precipitation event and subsequently wheat yields,” DeLaune said.
“Initially we found that cover crops can use significant amounts of soil moisture compared to treatments that have no cover crops.”
The question is, he said, is can that soil moisture be replenished?
“Are we increasing or improving soil health enough to encourage soil moisture infiltration after the termination of the cover crops?”
In addition, DeLaune said he has found that water use varies between cover crop species. Even when soil moisture was lower throughout the growing season with some cover crops, this was not translated to crop yields, indicating that other factors, such as nutrient cycling, may be playing an important role.
The results won’t be immediate, he warned.
“This is a long-term process. It takes several years to build up soil carbon, which is one of the main factors in increasing soil infiltration in changing soil properties, so we can’t expect to see changes that will tell us where we are going in two or three or maybe even five years.”
“Initially we might not see the changes,” DeLaune said. “It is something the farmer is going to have to be dedicated to, committed to and understand that it is a long-term process before possibly seeing the benefits of the system.”
For more information about the use of cover crops or for the results of the cotton study, contact the extension office at (940) 538-5042.