Compaction hinders drainage | Subsoil cultivator breaks up clay to improve water penetration
Many farmers are blame hardpan for their flooded fields and standing surface water.
The theory behind blaming flooded fields on soil compaction is that water goes only as deep as the loose topsoil in a wet year.
When it hits the compacted layer, it stops moving and ponds up.
Loose topsoil becomes saturated like a thick soup, but soil below the hardpan layer doesn’t get the drink it needs. As a result, it can become drier than the topsoil.
Some producers are pointing more than an accusing finger. They’re also pointing hard cold steel and high horsepower at the offender.
Rolly Waters of Brandon carried out field tests last year with a Case ripper he borrowed from a neighbour.
“The roots were healthier and went a lot deeper in the strips where we ran the deep tiller,” he said.
Those good results encouraged him to buy a Sumo subsoiler.
“We moved here from the United Kingdom five years ago. We had a Sumo subsoiler over there, so we already knew how it works,” he said.
“We farmed heavy clay and we were at sea level, so it was necessary to do every field every year.”
Mick Cornwall farms near Carlyle, Sask., with a range of soil on his 7,600 acres. He said he has compaction, but with such a varying landscape, the compaction runs from zero to serious.
Cornwall imported Canada’s first Sumo last year. He has since sold it and bought a second generation Sumo. He said the new subsoiler does not have discs.
“Last year we ran anywhere from eight inches down to 18 inches, trying to find the right depth, the sweet spot,” he said.
“We seem to have the most compaction at six inches to eight inches. So this year we’ll run at 10 to 12 inches, just slightly under the hardpan. My plan is to do 25 percent of the farm per year, but that depends on the weather.”
Subsoiling 1,900 acres every fall with a 19-foot cultivator at a ground speed of four m.p.h. might seem like an impossible task, but it’s not quite what Cornwall has in mind.
“After we’ve done the whole farm once, we’ll have a better idea which areas to leave alone and which areas need more attention in the future. The other thing to consider is that in the right conditions, we can run at seven m.p.h. when we’ve got the machine set at eight inches. So that speeds things up.”
He said breaking up of the hardpan isn’t the only point of using a subsoiler.
“Aeration is important. Wherever you run the Sumo, you end up with loose fluffy soil under the top firm layer. That means oxygen is getting into your soil, and that is important.”
Lincoln Wolfe of Portage la Prairie, Man., said compaction is a problem even in his area’s light soil.
“It’s mainly a sandy loam, but as you dig deeper it becomes more of a clay. That’s where the compaction starts,” he said.
Wolfe bought a nine-leg Sumo subsoiler to attack the problem.
“We did a little bit of testing with it last fall,” he said.
“Of course, we won’t really know how well it worked until spring, but we’re happy with the condition of the soil. It left a smooth firm seedbed.”
Arthur Bell used deep rippers regularly where he farmed in Ireland before moving to Boissevain 12 years ago. He bought a nine-leg Sumo subsoiler this winter.
“We have a clay-loam soil, and we get our worst compaction in the headlands,” said Bell.
“Roots and water just cannot penetrate the compacted layer. And in a dry year, even if there is some moisture below, the roots can’t get to it. The only solution is you must go in with a machine to break it up. I expect to do 20 percent of my land each year. So each field gets done about once every five years.”
However, the implications go beyond immediate crop damage in the year of the flood and mud. It also affects future crop years because the lower soil horizons have been deprived of the moisture necessary to replenish long-term reserves.
Even if producers use a ripper to give roots a chance to go deep, moisture in the lower zones may be far less than what was hoped.
In essence, it’s a man-made drought.
“I’d say compaction is part of the reason for surface flooding,” says Waters.
The problem compounds in a dry season because the soil above the pan dries out quickly and the roots are helpless.
Although Waters’ farm generally has light soil, he said proper internal drainage is impossible because of the thick hardpan at a depth of eight to ten inches.