Editor's Note: This article was originally published in January 2013 on No-Till Farmer.
Diversity Above the ground leads to robust soil health that powers profitable crop production, says no-tiller Gabe Brown.
Continuous no-till and a polyculture consisting of more than 25 different crops annually has increased yields, reduced input costs and solved a lot of problems for the Bismarck, N.D., no-tiller and rancher.
“As farmers, we sometimes spend all of our time treating symptoms,” Brown says. “Lack of fertility, compaction — I don’t care what it is — pretty much everything we’re trying to treat is a symptom. It’s not really the root cause of the problem.
“The cause of most of these symptoms, in my mind, is poor soil health.”
Brown focuses on feeding the soil, and letting the soil feed the crop. He accomplishes that with a diverse no-till system of cash crops fortified by a nearly constant rotation of cover crops.
With no commercial fertilizer, fungicides or pesticides — and limited herbicide use — the Brown family had a farm average of 159 bushels per acre for their 2011 corn crop. The cost per bushel was $1.09, not including land costs. Annual rainfall is 16 inches, and the county corn average is less than 100 bushels per acre.
The keys to reducing production costs are found in letting the soil do the work, and that requires organic matter, he says. When Brown and his family purchased their operation in 1991, fields ranged from 1.7% to 1.9% organic-matter content. In 1994, the farm went no-till, and by 2011 organic matter had increased to a range of 4.3% to 5.3%.
Despite the dramatic increase, Brown says there is plenty of room for improvement. Healthy native range has 7% to 8% organic matter, and that is the ecosystem model he emulates.
Cutting Fertility Rates
How do no-tillers improve soil health?
“That answer is to imitate native range,” Brown says. “No matter what you grow, you need to look back and ask yourself what the native range in your area looks like.
“We have to grow carbon, or in simple terms, organic matter. Two-thirds of your organic-matter increase will come from roots. You have to have living roots to feed microorganisms. The longer we can grow things, the more we can feed the soil biology.”
Brown has also used covers to cut back on fertilizer use, but he didn’t do that cold turkey. As no-till and cover crops began to build his soil, he reduced fertilizer application about 25% per year, until he had 4 years in a row where split trials showed higher yields in non-fertilized ground than in those that were still being fertilized.
Despite relatively low soil-test numbers, tissue analysis on Brown’s farm continues to show adequate levels of nitrogen, potassium and phosphorus.
“Am I telling you to drop your N, P and K fertilizer rate? No, you can’t do that. It would be a wreck,” Brown says. “You need to address soil health first. Once you get that going, do a test plot and start backing off fertilizer rates a little at a time.”
There are as many as 25 different crops grown on 2,000 acres of Brown’s cropland. Cover-crop mixes complement his cash crops, increase organic matter and build soil life. Cover crops are always polycultures because you don’t see monocultures in nature, Brown says.
Polycultures are grown before and after cash crops, and sometimes even as companions to cash crops. Brown’s aims to provide diverse species from warm-season grasses, warm-season broadleaves, cool-season grasses and cool-season broadleaves to deliver diverse food sources for soil biology.
“It’s not only the different crop types,” he says. “We have cool- and warm-season grasses and broadleaf species, but we also have different root types, so we’re addressing all areas of the soil. We have fibrous roots, tap roots, legumes and grasses all mixed together. The different leaf types collect as much sunlight as possible. The more plant species you have, the more power you have.”
Brown stresses diversity in cash crops as well as cover crops. His cash crops include corn, wheat, oats, triticale, alfalfa, sunflower, hairy vetch, red clover and peas.
Cover crops grown to support them — as well as the soil they grow in — include canola, radish, turnip, lentil, sweet clover, phacelia, subterranean clover, buckwheat, kale, sugarbeet, cowpea, soybean, sunn hemp, annual ryegrass, hybrid pearl millet, German millet and sorghum sudangrass.
Value Of ‘SOM’
Soil organic matter (SOM) has value. Brown estimates 5% SOM in the top 6 inches of soil in an acre (2 million pounds of soil) has a nutrient value of $3,755, compared to $751 for 1% SOM. That’s based on 0.56 cents per pound of nitrogen, 0.67 cents per pound of phosphorus, 0.54 cents per pound of potassium, 0.50 cents per pound of sulfur, and $4 per ton of carbon.
Additionally, farm ground that holds 2 inches of water per foot of soil, at 1.5% organic-matter content, holds approximately 3.75 inches of water at 4.5% organic matter.
“I can’t understand why more farmers don’t concentrate on organic matter, because that’s where the value is,” Brown says.
To build organic matter, planting crops with high root mass is important because most of the organic-matter increase comes from plant roots. Various types of rye are excellent for that purpose, he says.
Individual no-tillers have to analyze their own soil situations to decide what cover crops they need. But Brown strongly suggests using a wide variety.
“Fit them into your rotation to feed soil biology and improve soil health,” he says.
Planting Into Covers. Brown has used a number of strategies planting corn into living cover crops. But he cautions that no-tillers must check crop-insurance regulations before planting into live cover crops.
Following a cover-crop mix that included triticale, hairy vetch and sweet clover, he used a herbicide to knock back the triticale and planted corn into the residue, while the hairy vetch — although temporarily held back — continued to grow.
The hairy vetch helped provide nitrogen for the corn through the growing season and also helped suppress weeds. Brown then wintered cows on the vetch and corn residue.
Hairy vetch may not be the best choice in higher-rainfall areas because it can be competitive, Brown says. But on his farm, it pays for itself as a forage crop.
“If you have livestock, that’s one way to get a cash return right away out of those cover crops — graze livestock on them,” he says.
Brown uses mob grazing — extremely high stocking rates for very short durations — to mimic the bison herds that once grazed native ranges. He says grazing stimulates plants to release root exudates that feed the soil biology.
“Half for the critters below the ground, half for those above the ground,” he says.
Brown has also grown corn in subterranean clover, seeding it just ahead of corn planting or spinner-seeding it into corn 6 inches to 8 inches tall.
Herbicides aren’t used, and the covers — in addition to feeding the soil biology — provide nitrogen for the corn and moisture-saving cover as well.
“There are a lot of ways to get the cover crop out there,” he says. “The important thing is to get it out there.”
Above And Below
One of the cool-season cover-crop mixes that Brown seeds in the spring includes peas, oats, spring triticale, vetch, red clover, turnips, radishes and sugarbeets. This mix addresses organic-matter production, water infiltration and nitrogen production, as well as stimulating soil microbiology.
Plant diversity also has an above-ground impact. Brown cites a South Dakota study in which, despite 1,000 corn rootworm larvae per foot on continuous corn ground, damage at harvest was less than 1%. Minimal insect impact was the result of surrounding cover fields teeming with predator insects, he says.
“That’s the power of diversity,” Brown says. “What do you want to write checks for — triple-stack genes? Or do you want to just put some seed in the ground and do it in a natural, sustainable way? It can be done. This isn’t rocket science. Nature figured it out long before we did.”