BRANDON – The practice of light tillage before seeding can eliminate weeds, help prepare the seedbed by fluffing the soil and dry the surface to speed up the work in wet years. Light tillage can be used in the spring or for a fall-seeded crop.
However, there are some drawbacks, said Todd Botterill of Salford Tillage Specialists. Zero till farmers are reluctant to risk burying crop residue. Farmers who do preseeding tillage run the risk of creating a smear layer that will inhibit root growth of the new crop.
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“A shovel or a sweep comes along and skims just below the surface at three or four inches. That part is OK. But it creates a smear layer, a layer with slightly higher soil density where the tillage tool runs,” Botterill said.
“That smear layer does two things we don’t like. First, it prevents valuable soil moisture down below from migrating up to the roots. It seals the moisture in where it can’t be accessed.
“Next, as your roots start to develop in that three or four inches of fluffy surface soil, they naturally travel down for moisture. But they run into that secondary dense layer, the smear layer. When that happens, the roots spread out horizontally. They grow along the top of the smear layer looking for moisture. That’s the course of least resistance. They can’t break through it.”
Botterill said the crop will look healthy early in the growing season, especially if there are showers to replenish moisture in the top layer of loose soil. But once that moisture is used up, the crop suffers.
There may be an abundance of moisture below the smear layer, but it’s not available to the crop.
He said the Salford farm machinery company, located in Salford, Ont., has developed a system it calls surface tillage or vertical tillage. The tillage tool only functions vertically. It never travels horizontally, so it doesn’t create a smear layer.
“Surface tillage is any tillage that runs less than the depth of your seedbed or seed placement zone. So we’re looking at an inch and a half to two inches. Just down to where you’re going to place your seed, because we don’t want to disturb any more of that deep moisture than necessary.”
Botterill said the surface tillage opens up the soil to let it warm up and dry out. With no secondary dense layer below the tillage zone, the seed will be placed in undisturbed soil.
He compares the Salford concept to that used by the latest generation of high-end zero till openers that are engineered to place the seed in undisturbed soil.
The difference is that surface tillage provides the benefits of the best possible seedbed along with the advantages of a shallow cultivation.
“I’ve seen situations where the ground is too sticky to go seeding. They hit the field with a vertical tillage tool like this and two hours later they’re out seeding and kicking up dust from the loosened surface. But when you dig down to where they placed the seed, it’s resting on a huge amount of moisture,” Botterill said.
“It doesn’t matter what type of opener you use, with the top two inches of soil loosened up just before the drill comes along, you get more accurate seed placement, better closure of your seed trench and better packing.
“Especially in heavy clay soils that dry and crack, you don’t see your seed trench cracking and opening up by itself two days after you seed. It stays closed.”
Botterill said that in soybean demonstrations, the Salford system has created an early planting advantage of up to 10 days.
Botterill said the question he hears most is about the loss of protective residue associated with tillage.
He said Iowa farmers on erosion-prone soil are required by law to maintain 90 percent of the surface residue. Producers there who use the Salford system are able to do the preseeding surface tillage and still meet the legal requirement for surface residue.
He added that the surface tillage concept helps dedicated zero till farmers who are forced to seed late because of wet, cold soils.
Botterill said the Salford engineers did not depend on any one technique to achieve their goal, but rather put together a package of pieces that work as a system. He said any single component will not achieve the goal.
The first piece of steel to hit the dirt is the rippled coulter. The coulters come in 17 inch or 20 inch sizes and are available with either eight or 13 ripples. They are mounted on seven inch centres.
“The coulters are only there to fracture the surface, not to dig up a lot of soil or moisture. The wavy action fractures the soil out sideways, rather than pressing down. Downward tool pressure is what creates the smear layer. Sideways action is the key.”
The Salford system is designed to run at speeds up to 12 mph. Botterill said those speeds are possible because of the coil springs used to mount the coulters.
“The coils let the coulters move around. With a typical coulter setup, even if they’re spring loaded, you don’t have the give when you hit rocks.
“But a coulter mount like this wraps up in the coil winding to absorb the shock and vertical movement. And it also gives us side movement. If you just glance off a rock with the typical coulter mount, there’s no means for side deflection, so you can break the coulter. Since we’ve gone to the coils, we have yet to break a coulter.”
The coulter is followed by three bars with coil tine harrows.
Next in line come the 14 inch rolling baskets. All components are adjustable so the operator can get maximum surface disturbance with a minimum of disturbance down where the seed goes.
The tines and baskets leave a smooth surface for more accurate seed placement and a better field for spraying and harvest operations Botterill said.
“At five to six mph, it needs five to six horsepower per foot of cultivator. When you get up to 12 mph it’s more like 10 horsepower per foot of cultivator.”
Although operating costs vary with ground speed and equipment settings, the cost per acre is $3 to $4.
Although Botterill does not have Canadian prairie yield data yet, he does have data from the corn and soybean states.
A four year study in Illinois showed an average benefit of eight bushels of corn using the vertical tillage system before seeding.
Studies have shown yield increases as high as 20 to 25 bu. in corn and soybeans. The Monsanto Center of Excellence recorded an 11 bu. benefit on corn.
“In dry years, you naturally see a bigger yield advantage than in wet years.”
The Salford surface tillage system with coil-mounted coulters, coil tine harrows and rolling basket sells for $2,000 per foot. It is available in widths from 12 to 50 feet.
For more information, call Todd Botterill at 204-221-5212 or visit www.salfordmachine.com.
