Cover crops and conservation tillage have been slow to take root in the Texas Rolling Plains, but producers may be remiss in not considering the potential benefits.
Water demand for establishing and maintaining the cover has been an obstacle in this drought-prone area, says Dr. Paul DeLaune, Texas A&M AgriLife Research environmental soil scientist in Vernon. But after compiling economic data this past year, he asks, “Can you afford not to adopt cover crops?”
DeLaune says irrigated producers especially could realize more dollars per acre by including a cover crop on continuous cotton.
He’s been researching conservation tillage and cover crop effects on soil moisture and soil properties for the past eight years in the semi-arid environment of the Rolling Plains, with much of the data collected during an exceptional drought period.
He will be talking in detail about agronomic and economic impact of cover crops in cotton systems at the Beltwide Cotton Conference in Dallas Jan. 5-7 and the Red River Crops Conference in Childress Jan. 24-25.
WATER IS LIMITING FACTOR
“Water is often the limiting factor to crop production, so anything that is perceived to reduce the capability of soils to capture and retain rainfall hinders adoption,” he says.
Conservation tillage, which has shown benefits in regard to rainfall retention and storage, has been a hard sell in Texas, DeLaune adds, with only about 16 percent adoption. He expects cover crops to have an even lower adoption rate. However, he’s witnessed more promotion and excitement for cover crops due to the U.S. Department of Agriculture Natural Resources Conservation Service Soil Health Initiative.
DeLaune had hoped, after five years of research, to see a buildup of organic carbon in test plots – but didn’t. But he did see a reduction in overall soil compaction and an improvement in water infiltration.
“The stored soil water at the time of termination of a cover crop will be lower, but when the rain does come, the infiltration rate is higher, and prior to the cash crop being planted, it seems to be recharging well,” DeLaune says.
Termination date can be important. Terminating too early results in loss of beneficial residue. He terminates about a month before planting. “If you terminate early, the residue goes away quickly,” DeLaune says. “So when do you pull the trigger on termination? Let it get a little further along so the residue remains. Our infiltration data shows it will definitely be a benefit.”
In continuous cotton systems, his research has shown that infiltration did not differ between conventional till and no-till systems. “But we did see a significant increase in infiltration when a terminated wheat cover crop was added to the system. In a low-residue system such as continuous cotton, no-till alone does not seem to be as beneficial in regard to infiltration, although we have seen alleviation of plow pans with no-till.”
COVER CROP OPTIONS
The continuous dryland cotton system he has researched included trials of conventional till, no-till and no-till with a mixed species cool-season cover crop, as well as monocultures of crimson clover, hairy vetch, Austrian winter field pea and wheat cover crops.
Over a three-year average, expenses were significantly lower for the no-till system than all other systems except the wheat cover crop, he says. Seed is a major factor and wheat has a much lower seed cost compared to other evaluated cover crop options.
In less humid regions, it is important to consider reasonable cover-crop seeding rates and not try to emulate high seeding rates that may be seen in cooler or wetter climates, DeLaune says. Within the dryland study, economic returns were not significantly different between cover crop and non-cover crop treatments.
“Although we have seen significant soil moisture use by cover crops, we have maintained lint yields with cover crops,” he said.
On irrigated cotton, the lint yield and net return were higher for the mixed cover crop and wheat cover crop systems in the third year of the trial. On the three-year average, per-acre net returns were $355 for no-till, $367 for conventional till, $398 for wheat cover crop and $406 for mixed species cover crop systems.
Added residue, either through crop rotation or cover crops, is a benefit to cotton systems in semi-arid environments, he says. Risks are much greater in dryland systems, but success is possible with educated management decisions.