Resource concerns drive seed mix composition when developing cover cropsWritten by Natasha Wheeler
Casper – “I speak to a lot of seed dealers selling cover crop seed, and I tell them that their first question should be about resource concerns. Otherwise, they are just trying to scam customers for money,” stated Gabe Brown of Brown’s Ranch in Bismarck, N.D.
Cover crops, he explained, should be designed for whichever elements producers are missing.
Brown spoke during a presentation sponsored by the Wyoming Natural Resources Conservation Service and the Planck Institute on March 27 in Casper.
“Do we want to increase organic matter, infiltration or pollinators?” he asked. “Do we want to feed livestock or attract wildlife?”
Depending on a producer’s end goal, cover crop mixes should be tailored to meet specific criteria.
“If soil health is our goal, diversity can not be ignored or overstated,” noted Brown.
He referred to different management challenges as “symptoms” and provided some suggestions for treating or alleviating them.
“To treat poor soil structure, we can use a mix of species that will proliferate mycorrhizal fungi, such as sorghum sudangrass, rye, oats, millet, wooly pod vetch, sunflower, buckwheat and clover,” he explained.
Plants that support fungi growth help to build soil aggregates that improve soil structure.
“Another symptom is low organic matter. We can improve that significantly by having roots in the ground,” he continued.
Creating diversity both above and below ground is important for increased organic matter, according to Brown.
“When we have a monoculture, we have one leaf size and shape and we’re only collecting a certain amount of sunlight. If we have different leaf sizes and shapes, we will maximize photosynthesis, put more root exudates into the soil and increase organic matter because we are optimizing solar energy production,” he explained.
Cover crops can also be used to manage pests by catering to species that drive pests out of the field.
“For every species that is a pest, there are over 1,700 species that are beneficial,” Brown stated.
When pesticides or other methods are used to kill pests, many of the beneficial species are killed as well.
“Ladybeetles are some of the most vicious predator insects there are. They will take care of a lot of the pest insects,” he continued.
Buckwheat contributes to soil health by cycling phosphorus, and it is also a crop that can be planted to attract bees and other pollinators.
“All of my mixes have some flowering species in them because I want to provide a home for predator insects, so I don’t have to worry about pests,” he noted.
Another problem that Brown addressed was slow residue composition, which he attributed to an unbalanced ratio of carbon and nitrogen.
“Until our soil health builds up and we have the micro- and macro-organisms to cycle nutrients, we have to pay attention to our carbon-nitrogen ratios. That is pretty easily managed by expanding our crop diversity,” he explained.
Radishes, for example, can be added to a mix to help balance out soil nitrogen.
“We have to get four things right in our cover crops – the right species, the right inoculants, the right seeding and the right seeding time,” Brown said.
Producers should review the elements of their operation including their environment, dry land or irrigation, evaporation rates, growing season, soil types, seeding methods, planned crops, previous crops and herbicide use.
“Too many times I have seen people lose entire cover crops because they used an herbicide with a long carry-over,” noted Brown.
Producers should know the effects of their herbicides before spending money on cover crop seeds.
“We have to figure out our resource concerns,” stated Brown.