Conservation tillage and compaction

It makes good sense, says Texas A&M agronomist Charles Stichler, to be as frugal as possible with crop tillage, but continuous no-till, especially in heavy soils, may cause problems.

Continuous no-till, Stichler said at a recent field day at the Texas A&M Stiles Ranch research center at Thrall, works well in the Midwest, where cool temperatures from fall through spring allow farmers to build organic matter in soils.

In Texas, however, shorter cold periods allow organic matter to break down faster. It’s less of a problem in irrigated land, he said.

Growers often begin to see problems after four years of strictly no-till. “For the first two or three years they have no trouble,” Stichler said. “But after the third year, heavy soils begin to get hard. Plant roots begin to follow the seed slit and away from compaction zones.”

Stichler said double disk openers may seal off seed trench walls, preventing roots from penetrating, especially if the soil is a bit moist at planting time. “Roots get trapped in seed trenches,” he said. Limiting root movement may prevent plants from absorbing adequate moisture and nutrients.

“Farmers don’t have to use a strict no-till system every year,” Stichler said. It may make as much sense to rotate tillage methods as it does to rotate crops. He’s studied conventional tillage, strip-till and no-till systems.

He says he’ll revert to a ridge-till system for much of his work at the Luling Foundation Farm in Luling, Texas.

“After corn or soybeans, I’ll do some fall tillage and put in rows around November,” he said.

Stichler said he’s seen fields in Wharton County that have been in continuous ridge-till for 11 years, following the same rows with each crop. “Roots are beginning to grow in a flat, fan-like pattern and the fields need some tillage to break the soil up again.”

He said no-till in the Southwest “might be different if we could build more organic matter. Even with strip tillage, we see a tomahawk pattern with root growth, although they grow more normally than they would in continuous no-till.”

He said today’s conventional tillage system is a far cry from what farmers practiced just a few years ago. “Most have switched to some form of reduced tillage system,” he said. “They’re finding ways to limit the number of trips they make across a field and still get the soil in good shape to get the crop growth they need.”

Stichler said closing wheels also play a role in reduced tillage success. Wheels that are overly aggressive may throw too much soil out of the planting slit. Some toss the seed out with the soil. He said one of the best he’s seen is an after-market wheel, a 15- inch diameter with spikes that fit over the rubber wheels of a John Deere planter.

“Farmers may want to keep two different types of closing wheel on the farm, however, and choose one based on current soil conditions.”

He said farmers who have used a reduced tillage system for several years should pay close attention to fertilizer placement. If placed too far away from the seed trench, roots will not penetrate the hard soils. “Put the fertilizer to the side but close to the seed,” he said. “Broadcast fertilizer application may not work with continuous reduced tillage.”

He also discussed the potential of using weeds as a cover crop for no-till planting.

“We can’t afford it,” he said. “We don’t want to let any weeds go to seed and just one in the field justifies action to take it out before it seeds.”

Stichler said limited rainfall should force farmers to do everything possible to control weeds. Left alone they take up moisture the crop will need to produce yield goals.

He said farmers may not want to go back to strict conventional tillage but tweak a reduced tillage system to improve soil tilth. He’s looking closely at a stale seedbed system as an alternative

“We may not go back to conventional and we may get away from strict no-till and do something in between,” he said.

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