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Sticking with no-till is worth it
By Larry Dreiling
From the moment raindrops strike the Earth, falling at 15 miles per hour, creating minute explosions and loosening soil particles, they continue to seek out the path of least resistance. The separated soil particles are carried downhill under the invisible force of gravity.
If the raindrop strikes a piece of crop residue, the energy of the falling raindrop is absorbed by residue and the water then slowly percolates down into the soil.
With just 30 percent crop residue cover, soil erosion can be reduced 60 to 70 percent.
That's the philosophy of just one speaker at a No-Till On The Plains Whirlwind No-Till Expo, held in Ogallala, Neb. Bud Davis, Kansas conservation agronomist for Natural Resources Conservation Service, was one of many presenters offering information and advice to nearly 100 producers in attendance.
With a demonstration of how rainfall behaves on broken soils that have been under no-till and those that aren't, Davis explained how falling raindrops affect the soil.
"Soil is a composite of all types of different things," Davis said. "It has chemical and biological processes. It has a mineral base of sand, silt and clay. It's the clay and organic matter that binds those things together. It's the microorganisms in the soil that process the carbon and residue that comes into that soil. By the breakdown of those things, it becomes the glue that sticks those particles together."
When there is little organic matter in the soil, the aggregates in the soil are not very stable. By building more organic matter in the soil, erosion can be reduced.
"The easiest way to do that is to reduce the tillage and the other stresses we place on soils by mechanical manipulation," Davis said. "Every time you till, that oxides the soil, it breaks down the organisms faster."
Using several different soil types, from native grass to samples from an operation in no-till for nearly nine years and a conventional-till operation, Davis showed how no-till acts as a soil binder when water is applied to them.
"The particles just fall off the conventional-till material. What you are looking at is unstable aggregate," Davis said, as he described the conventional-till soil.
His description of the no-till soil was different.
"This is likely windblown soil, a fairly young soil," he said. "It may fall apart because it's sandy, but the organic matter is what's going to hold it together. That's real important, because sandy soil can seal over, just as clay and silt soils can.
"What we are trying to do is reclaim some of that organic matter, which is a part of the natural condition of soil that we broke out of the sod. Some of the soils we'll never get as good as we'd like to, but if we can make a stand toward improving organic matter we'll be able to enhance the ability of the soil to deal with the conditions that yield to it."
Davis said it takes time to build the aggregate in the soil. It may be discouraging at first, because in the first years, unstable aggregates remain on top of the ground.
"You have to go through a process that builds that aggregate. You can imagine the first time the sun shines on soil that you just started to no-till. It has a hard surface. That's one of the complaints we hear from people who go into no-till that their soil gets so hard out there that they have a hard time with their drills and planting systems.
"This is something you have to deal with at first. It's a case of timing, especially in the initial years, to be out with their equipment at the right time."
Another case for patience came from Paul Jasa, University of Nebraska-Lincoln Extension engineer for no-till system management and precision agriculture, offered a demonstration of how soils from no-till--even soils in no-till for 20 years--and conventional-till may look alike at the surface, but deep down, no-till soils beat conventional-till soils for yields.
"Even in wet years, no-till wins, because it's not a moisture conservation thing," Jasa said. "In long term tests, we've been getting rainfall into the soil so it can store it. Now, we can look at harvesting our water and growing our crops."
Using a set of tea strainers filled with the different soils, Jasa poured water into them to simulate percolation through the ground.
"Before the soils get wet, these soils may not look much different, but as you wet them thoroughly, the difference is clear. No-till builds water-stable aggregates," Jasa said. "To put in terms, I told a fifth-grade class, one is like chocolate pudding and the other is like brownie mix."
Plowed ground is about 2.5 percent organic matter, Jasa explained. The no-till ground is over 4 percent in the top layer and 3.8 percent at the eight-inch layer. Those differences aren't numerically significant, but as soils are defined, they are.
"What matters more than anything is that people stick with no-till," Jasa said. "The soil I have here is 23 years old. What makes no-till work is continuousness. You can't build structure like this with one-pass tillage or 'skip-a-till'. You just broke that down and now you'll start over again."
Jasa indicated he has seen research showing that it would take 15 to 20 new no-till cycles to make up for the use of just one tillage pass.
"Guys who stick with no-till may pick up three to five cycles a year," Jasa said. "After about year five, no-till wins every year. It takes that long to build up the soil structure, to support the weight of the implements. It takes that long to build up the roots of the soil.
Jasa also has researched the bulk density and tilth of his no-till and conventional plots, with interesting results.
"Tillage has beat down the soil," Jasa said. "It reduced the pore spacing. It made it denser. No-till soil is fluffier and taller because it has more air in it, more moisture-holding capacity, more organic matter, more pore spaces for which to penetrate. The height is visually different.
"Originally, I thought it was just erosion that made the ground look shorter. It's not. It's that no-till makes the soil look taller. It's made the soil fluff down, rather than fluff it up. Just stick with it."
Larry Dreiling can be reached by phone at 785-628-1117 or e-mail at ldreiling@aol.com.
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