Cover crops build soil health
By Pat Sunderland
Published Thursday, November 19, 2015 10:45 am
Photo by Pat Sunderland Jerry Allen discusses the unique seed mix used to create a cover crop on a field in the Pea Green area. Producers are encouraged to mix their own "cocktails" to address specific issues.
For five years, Ahlberg Farms has been disking under corn stalks and onion tops soon after harvest, then reseeding with a unique blend of seed mixes to produce a cover crop that provides forage for livestock and nourishes the soil.
The practice is one that has many benefits, according to the experts on the Uncompahgre Soil Health Team.
Last week team members hosted a tour of six farms that are employing cover crops to increase organic matter, increase nutrient cycling, suppress weeds, reduce soil compaction, provide forage for livestock, provide cover for wildlife, and potentially break disease and pest cycles.
The team points to the four practices that promote soil health:
• Keep the soil covered for as long as possible.
• Minimize soil disturbance.
• Keep a living plant on/in the soil throughout the year (or as long as possible).
• Diversify the types of plants growing on the field through crop rotations and cover crops.
Three out of four of those practices involve cover crops, described as annual and semi-annual plants grown for seasonal vegetative cover as part of a planned rotation to provide soil health benefits. There are also benefits to the principle cash crop, as evidenced by the higher yields, quicker maturity and larger onions/ears of corn the Ahlbergs have been harvesting since they began the practice of planting cover crops.
Zach Ahlberg has refined the seed mixture over the years. His most recent mixture consists of triticale, sorghum, sudangrass, hairy vetch, Austrian pea, purple top turnip and Daikon radishes.
As the cover crop matures, cows are let out to graze on the nutrient-rich mixture. Their droppings further add to the organic mix in the soil.
Adding organic matter to build carbon is the key to soil health, said Katie Alexander, a soil conservationist with the National Resource Conservation Service.
Steve Woodis, NRCS biologist, points to the "cottage cheese" quality of the soil, referring to the loose soil structure that results when deep-rooted plants like radishes, canola and some annual grasses are planted. These plants can reduce the need for mechanical deep ripping.
Another benefit, said Dave Dearstyne, is that the soil holds moisture better than a fallow field.
The composition of the cover crop is specific to the individual need, and can change each year to address common issues such as weed control, disease control or nitrogen balance.
The cost of the seed is often covered by the grazing value, noted Jerry Allen of the Shavano Conservation District. Increased yields also make cover crops worthwhile.
The goal of the Uncompahgre Soil Health Team is to help producers maximize soil health by increasing organic matter through cover crops, green manure, grazing, compost, entomology and other sustainable practices.
The team also helps put on the annual Western Slope Soil Health Conference, which will be held Feb. 11-12 at the Delta Center for the Performing Arts and Education. More information can be found at www.westerncoloradosoilhealth.com.