What is in this article?:
- Cover crop trials to improve Arizona cotton production
- Drip irrigation
- The University of Arizona and the Natural Resources Conservation Service are conducting commercial field trials designed to improve Arizona cotton production systems through improved soil quality with cover crops.
One of the reasons for cover crop interest is subsurface drip irrigation which is gaining traction due in part to water availability concerns. About 1,100 acres have drip. Drip eliminates deep tillage practices so farmers shift to minimum till or no till. Cover crops become a viable production option.
As with other cotton-growing areas, it is difficult for farmers to budge from a century-plus history of deep tilling meticulously clean fields each spring.
“Trying to get these guys to be ‘trash farmers’ with cover crop residue has been a chore,” Foster chuckled. “They are used to clean tilled fields but understand change can increase productivity and efficiency.”
Drip irrigation and reduced tillage allow farmers to maximize soil health, Norton says. “It’s amazing to walk on the spongy, porous soil created by the cover crops.”
On the Thatcher farm last year, a barley cover crop generated about 4,100 pounds of residue per acre on the field surface. By the cotton harvest window, the majority of the residue was in the soil. This is a strong indicator of soil health, Foster says. Microbial action helps release nutrients from the organic matter for uptake by the cotton plant.
The owners of the Thatcher trial field, Denny and Lance Layton of Layton Farms and Ranches, are enthusiastic about cover crops. This spring, they installed a row cleaner on the cotton planter to remove residue from the top of the seed bed.
Foster says generating natural nutrient value from cover crops reduces the need for commercial fertilizers while still achieving maximum cotton yield.
“Maximum yield does not always mean max profit,” Foster said. “Through the trials we are illustrating that you can maximize your profits by minimizing your inputs with cover crops and in fact make more money.”
Foster and Norton plan to conduct the trials for three years.
What cover crop lessons have been learned so far? Weeds have been substantially reduced with cover crops which save spray and cultivation costs. A nearby farmer saves $14 per acre from cover crop-controlled weeding in combination with reduced till allowed by drip irrigation.
Some cover crops may not prosper in the Gila Valley’s colder temperatures. The thermometer dropped into the single digits in early February for several days.
“The freeze burned the oats back a little,” Foster said. “The triticale kept growing. The snow peas tolerated the cold fairly well. The vetch took longer to germinate but took off once the temperatures warmed up.”
Norton and Foster are closely following the oats, focusing on the crop’s natural ability to reduce pathogens and nematodes. Legumes are new to the valley and could serve as a good cover crop because of their ability to “fix” atmospheric nitrogen and increase the soil concentration of that nutrient.
Seedling disease has been a major issue in the Gila Valley for the last two years; likely tied to cool temperatures and wind. Cover crops can also cause seedling disease due to reduced soil temperatures caused by the crops. Norton is experimenting with the fungicide Quadras applied in the drip to target the high residue-caused problem.
Farmers should be aware that cover crops must be managed and require time and money.
“You can’t just plant it and walk away,” Norton said. “Cover crops need to be watered. However, cover crop benefits, particularly in a drip situation, are well worth the costs associated with them.”
The trials are funded by the UA, NRCS, and the farmer cooperators. NRCS can offer first year matching funding for cover crops in cotton.
Other contributors to the project, all from Arizona, include: Sam Wang, UA Maricopa Agricultural Center, Maricopa; Art Meen, NRCS Field Office, Douglas; and Bruce Munda, NRCS Plant Materials Center, Tucson.