Dollar discussed reduced tillage systems recently at an Ag Technology Conference sponsored by Texas A&M- Commerce.
Conservation tillage offers farmers the fastest method to improve soil structure, he said.
And while soil gets better (Results become apparent within three to five years.), farmers also reduce erosion, limit runoff of sediment, nutrients and chemicals into nearby streams and may increase yields and lower production costs.
“We see some barriers to acceptance of conservation tillage,” Dollar said. He cited equipment expenses; weed problems; heavy, wet or cold soils; increased chemical use; yield reductions and insect problems as perceptions that may keep some farmers from trying conservation tillage.
“But we also can cite advantages,” he said. “Residue management, either from no-till, ridge-till or mulch-till, helps farmers manage crop residues or cover all year. Something always stays on the soil surface.”
He said farmers may opt for a minimal tillage system, such as ridge-till, in which residue remains in the bottom of the row while the farmer tills a narrow seedbed. Mulch-till leaves some residue on the soil year-round but may allow more residue disturbance than either no-till or ridge-till.
Either system, Dollar said, “reduces soil erosion. Studies show that the average loss on corn land is twice the sustainable level. Soil losses in cotton are not as drastic in the Blacklands area of Texas as in the windy plains.”
He said maintaining a cover crop or old-crop residue on the soil reduces “the splash effect of rainfall.” The cover cushions the soil and allows droplets to spread over the surface and penetrate instead of packing the soil or displacing soil particles.
“Conservation tillage reduces surface runoff and increases water infiltration potential,” he said. “With just 10 percent residue coverage, a farmer can reduce erosion by 30 percent. With 80 percent coverage, he can cut erosion loss by 94 percent.”
He said residue reduces the velocity of water on the soil surface. “With low-residue crops farmers may want to add a winter cover crop to meet erosion control goals,” he said.
“Managing crop residue also retards water evaporation,” he said. “Farmers can save from two to four inches of water per year, just by managing surface residue. That may increase yield potential for some growers.
“In humid areas, moisture savings could be detrimental in some years. With timely rains, yield increases may not be evident.”
He also cautioned farmers to watch soil temperatures more carefully with conservation tillage. “Soil temperatures will be cooler in the spring. Strip-till or ridge-till may help warm the soil in the seedbed and may improve root growth.”
Reducing tillage increases organic matter content, Dollar said. “Organic matter is an important soil quality factor and residue management can contribute significantly to increasing organic matter content. It’s better to hold carbon in the soil than to lose it.”
Dollar said building organic matter takes years. “With continuous no-till operations, organic matter content may double in 20 years,” he said. “But changes begin within just a few years.”
Those changes include: soil aggregate stability, improved water retention, better cation exchange capacity, and a better balance of micro-organisms that return humus to the soil.
He said leaving an old crop root structure in place also helps improve soil structure, allowing better moisture, nutrient and new-crop root penetration.
“We improve fertilizer efficiency with conservation tillage, too,” Dollar said. “In no-till systems, nitrogen releases more evenly during the growing season. We don’t get the typical flush of nitrogen that occurs in conventional tillage systems.”
Compaction can be as big a problem in conservation tillage as it is in conventional, Dollar said, if farmers don’t take care of existing problems before they convert to reduced tillage and if they don’t take precautions about re-creating hardpans.
“Compaction may be an extremely limiting factor in some fields,” he said. “It limits the amount of water the soil can store and restricts root growth. Make certain to correct any compaction problem before initiating a conservation tillage system.
“Also, once a farmer commits to reduced tillage, he should stay off the fields as much as possible when they are wet. Establish traffic patterns and stay with them,” he said.
Farmers also may decrease crusting problems with reduced tillage systems.
“Crusting can be a serious concern in soils with low organic matter and is more prevalent in soils that are excessively tilled. Crusting may interfere with crop emergence and may require an extra tillage operation to correct.”
He said managing residue will reduce crusting. It also reduces sediment loss.
“Texas is high in sedimentation,” Dollar said. “We’re concerned about soil washing into streams and other bodies of water. Also, phosphorus does not move into the soil readily but binds with soil particles and can move with surface runoff. Nitrogen and chemical runoff also pose potential problems.”
Maintaining residue on the soil surface, he said, decreases potential for soil, nutrients or chemicals moving off site. “We have a lot of potential for runoff in the Blacklands,” he said.
Dollar noted that Blacklands farmers have been eager to adopt conservation-tillage techniques. “Almost half the conservation-tillage corn acreage in Texas is in the Blacklands,” he said.
Eliminating tillage and maintaining residue or some cover on the land year-round offers farmers an opportunity to manage resources more effectively, Dollar said.
“We can reduce soil erosion, improve moisture infiltration and improve soil quality,” he said.