Writer: Beth Ann Luedeker
AgriLife Extension and the USDA Natural Resource Conservation Service recently teamed up to discuss cover crops and conservation tillage practices with producers in the Blackland region of the state. The group met at the Stiles Foundation Farm, near Thrall, and Unnasch Farms, near Hart, Texas.
Robert Unnasch has been practicing conservation tillage for many years. This made the field trip to his farm an excellent way to begin the day, according to the field day organizers.
“When a farmer talks, people listen,” said Nathan Haile of the NRCS. “Robert Unnasch has been doing this successfully for some time, so he has experience worth talking about.”
Haile pointed out that, according to the NRCS, there are 5 key elements for ‘soil health’ which are met by conservation tillage/cover crop practices: maintaining ground coverage; minimizing disturbances; maximizing diversity; maintaining growth year-round; and integrating livestock to redistribute nutrients.
“Cover crops should be planted as closely together as possible to aid in weed constriction, and to provide canopy to protect the soil,” said Dr. Haly Neely, Texas A&M University Soil and Crop Sciences faculty.
“If you close the canopy you reduce sunlight on the ground and air across the soil, keeping the soil cooler and drastically reducing evaporation,” she said.
Minimizing disturbances means leaving the soil alone as much as possible. Under conservation tillage practices, equipment enters the field much less frequently.
“Every time you till the soil you set it back in terms of organic matter and soil bio-ecology. Not all the way to zero, but back to the minimum that soil will support,” said Dr. Jake Mowrer, Assistant professor in the Department of Soil and Crop Sciences and Texas A&M AgriLife Extension Specialist for soil nutrient and water resource management. “Any time you disrupt the continuity of the soil it takes time to recover.”
Crop diversity provides many benefits, Haile said, and can improve pest and weed management in the field.
“Having different rooting systems keep root channels open,” said Mowrer. “The plants take up different nutrients and may redistribute them to different zones in the soil where they are more accessible to the successive crops.”
But think carefully about the benefit desired from a cover crop before selecting a species, says Mowrer. For example, to add nitrogen to the soil, plant legumes; to redistribute nutrients, plant cereals; to restore soil organic matter, plant something with a high biomass, he said. In addition, a farmer must select a crop which will work well in his soil.
“Keep something growing for as much of the year as you can,” Mowrer said. “If you don’t have a living root in the system you are missing something.”
Mowrer explained that most of what is known about cover crops comes from the corn/soybean rotations in the Midwest. It is important to gain information about what works in Texas to best aid the farmers here, so AgriLife researchers have several projects underway out at the Stiles Farm Foundation.
One ongoing project was discussed by Dr. Clark Neely, Assistant Professor in Soil and Crop Sciences and AgriLife Extension Small Grains/Oilseeds Specialist. His research is studying the feasibility of double cropping/cover cropping and reduced tillage on wheat cropping systems. In addition to the fields at Stiles Farm, the study is replicated in Lubbock and Beeville.
“We are looking at several double cropping options including grain sorghum, sesame, and cowpea. We also have a nine-species cover crop mixture. The thought behind double cropping is to see if we can get the same soil benefits as a multi-species crop mixture and also generate some additional farm revenue at the same time,” Neely said.
“The tillage component of the study compares conventional, strip-till and no-till systems,” he explained. “In addition to the soil health aspect of reduced tillage, we wanted to evaluate these double crops and cover crop mixture under each tillage system to see if strip or no-till made double cropping more feasible or reliable by conserving more soil moisture. We’ve found that strip or no-tilling double crops following wheat harvest does improve stands and ultimately yields due to greater soil moisture in the topsoil at planting.”
Based on preliminary results, sesame appears to have the best potential for generating a viable income followed by grain sorghum, Neely said. Another important finding so far is that these double crops are not having a negative impact on wheat yields, despite using more soil moisture during the summer months. The Blacklands region generally receives enough rainfall to recharge soil moisture by the time wheat is planted later in the fall.
“We are taking soil measurements on wet aggregate stability, soil infiltration rate and soil respiration, which can serve as indicators of overall soil health, but observable differences will likely take more time,” Neely said.
He and his colleagues will determine the profitability of the system through economic analysis after more years of data are collected.