With 25 years of no-till under their belts, brothers Mark and Bruce Watson have learned by trial and error. Coping with semiarid conditions on their farm near Alliance, Nebraska, the Watsons sidestepped the area’s traditional wheat-fallow system in favor of a diverse continuous-cropping rotation designed to conserve soil and moisture.
“This is a fragile environment here, where wind erosion is still a big problem on many farms,” says Mark, a Panhandle no-till educator. “Moisture is always a limiting factor, and our eroded, low-quality soils have poor moisture-holding capacity.”
As the Watsons evolved over time a continuous-cropping no-till system, they experimented with crops like proso millet, sunflowers, chickpeas, spring wheat, and others. “We were looking for crops that would fit our environment as well as our marketing outlets,” he says.
The crops they eventually chose to grow in their dryland rotation include winter wheat followed by corn and then yellow field peas. The rotation gives both short and long fallow periods, each matched to the moisture needs of the subsequent crop.
The peas are planted between late March and late April and harvested in mid-July. Winter wheat is then seeded into the standing pea stubble in mid-September.
“Between the harvesting of the field peas and the planting of winter wheat, we get a couple months of fallow,” says Mark.
The wheat is harvested the following summer in mid-July, and these fields then stand fallow over winter until the corn is planted in late April or early May of the next year.
During this nine- to 10-month fallow period, the Watsons hope to bank as much precipitation as possible for the corn, which uses a lot of soil moisture before it’s harvested in October.
Residue Is Key
Besides providing a long fallow period, the growing of winter wheat before corn also offers the moisture-saving benefit of tall residue after harvest. The residue traps snow to further recharge soil moisture.
“In order to leave a lot of standing residue to catch snow, we use a stripper header on the combine,” says Mark. “The residue also reduces soil-moisture evaporation, and that helps us produce corn on dryland acres. The more residue we have, the higher the corn yields.”
Leaving stalks a couple of feet tall after harvesting corn also helps trap snow.
“It’s actually easier to no-till into standing corn stubble than it is to plant into cornstalks lying on the ground,” Mark says.
The residue from both wheat and corn has a high ratio of carbon to nitrogen, which slows down decomposition of plant material.
However, growing peas behind corn initiates the breakdown of surface residue left from both wheat and corn. The pea stubble has a high ratio of nitrogen to carbon, and this speeds up the decomposition of plant material.
“By the time we plant wheat again, much of the buildup of surface residue has been broken down and recycled into the soil,” he says.
After more than two decades of no-tilling, soil quality and the processes of soil-moisture retention are showing signs of greater health.
“We’ve seen improvements in soil organic matter over time,” says Mark, “and the crop residue on the surface helps water infiltrate the soil. Our moisture-use efficiency is high because we capture most of the moisture we get by no-till and by continuous cropping.”
By comparison, moisture-use efficiency of tilled summer fallow is only 15% to 25%, he says.
Typical wheat-summer fallow systems in his area will lie fallow for 14 months.
“During that time, we might get 19 inches of precipitation, but the fallow will store only 4 to 6 inches in the soil profile,” says Mark. “Most of the moisture evaporates, runs off, and passes through the soil profile, where it can’t be used by the following crop.”
Present benefits aside, the Watsons’ system and its processes could be further improved, Mark says. Adding livestock may be their next step toward further advances in soil health and a resilient production system.
“Historically, the grazing of animals was a key component in the evolution of the High Plains,” says Mark. “The more we can mimic that, the better off our soil will be. We hope to work toward a system of planting diverse forages for livestock grazing.”
They are considering adopting a rotation of winter wheat, forages for grazing, and field peas.
“We would then take the dryland corn out of our operating system,” says Mark. “Corn is the crop most likely to fail in our environment.”
The new rotation could secure a more stable future for Bruce’s son, John, and Mark’s son, Jacob, as they work into the farming operation.
“Agriculture is dynamic. It involves a learning process and exposing yourself to making mistakes,” says Mark. “Like other farmers, we’re trying to make better use of our resources and become better stewards by improving the health of our soil.”
(Source – http://www.agriculture.com/crops/tillage/no-till/lessons-from-notill_188-ar47220)