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Deep tillage can be too effective

A deep tillage treatment on his Alberta Peace River region farm did what it was supposed to do, but Gary Sanocki wondered at times this past growing season if it might have worked too well.

Sanocki, who crops about 1,800 acres of grains, oilseeds and pulses near Eaglesham says the tillage in the fall of 2010 did loosen the soil profile, but then it was too soft for some field operations come the spring of 2011.

“It did present some challenges both at seeding and in field spraying operations,” says Sanocki. “In those fields where we had done the deep tillage it was a definitely a challenge to seed canola. We have a parallel link drill and we had to completely reset all the depths because the ground was so loose there was no support… there was definitely a lot of dirt moving around.”

The biggest challenge was in managing depth control to seed canola shallow. “Part of it was due to the fact it was the first season after the tillage treatment and we also had some heavy rains when it came time for spraying,” he says.

Sanocki, who farms along with his wife Fiona Love, treated about 700 acres in late 2010 with a 17-shank AgrowPlow deep tillage tool. Pulled by a 380 horsepower track tractor, the shanks were set on 13-inch spacing and he set them to till to a depth of about 12 inches. The shanks have a narrow opener, designed so they fracture the soil profile downward but create very little soil disturbance and little soil mixing.

Sanocki has been producing crops every year, but he has been somewhat disappointed with their performance in recent years. His area did have a drought for two or three years, which complicated things, but even when there was reasonable moisture, crops weren’t doing as well as he expected, despite proper nutrients.

“And I noticed in particular the roots of canola plants would grow straight for a few inches and then turn and go sideways, so I figured there was a compaction issue,” he says. He and some neighbours also investigated, slicing into the soil profile with a backhoe. “There seemed to be a layer in the nine to 13 inch range the roots couldn’t penetrate” he says.

Subsoiling is a slow and somewhat expensive process, he says. His wife did most of the work and drove at about 3.5 miles per hour, and that tool bar was at times all the 380 hp tractor could handle, especially when the tillage tool hit areas like an old lease road or trail where there had been repeat traffic. He estimates tillage cost in the $45 to $50 per acre range.

The soil was dry the fall of 2010. “Just about every 80 acres we’d have to stop and rebuild the tips on the shanks,” he said. “So there was a lot of maintenance in that respect.” He did a bit more deep tillage in the fall of 2011, after a wet growing season and it was a completely different story, as far as wear and tear on the machine was concerned. Tips didn’t wear nearly as much and the shanks didn’t over heat.

Sanocki says he could see a difference after deep tillage, during the winter that followed the first 2010 treatments and long before he started seeding. “The winter of 2010-11 we had snow cover and then a big thaw in January,” he says. “Where we had done the tillage all the water disappeared down and on fields we didn’t till it either ran off or just sat there and pooled up.”

After several dry seasons it was good to see the moisture, but the combination of moisture and loose soil made seeding in 2011 difficult. It turned dry after seeding and then they got 13 inches of rain in a three-week period in late June and July. That excessive moisture made it more difficult to travel on the tilled fields with the sprayer. There was no standing water but the ground was soft.

Results

Heavy rains just before harvest complicated harvesting of (untreated) check strips he’d left with each crop, so it was difficult to get an accurate measure with a yield monitor.

“Overall with canola I couldn’t say there was a big yield difference — maybe one or two bushels more,” says Sanocki. He had an excellent stand of wheat on the treated fields, but again wasn’t able to properly harvest the check strips. He estimates wheat on deep tilled fields yielded about 10 bushels more per acre.

There was quite a dramatic difference in pea crop however. Where he hadn’t deep tilled the crop stood about four feet tall and looked good, but where he had deep tilled it went down and laid flat.

“I was a bit concerned, but when it came time to combine it was a different story,” he says. “The crop that stayed standing had lots of growth but not that many pods and they didn’t fill as much. On the deep tilled fields the crop went down because it had lots of pods and they were full. So overall on the peas I had at least a 10 bushel per acre yield increase on fields that were deep tilled.”

Sanocki has a few observations after one year’s experience with deep tillage. Especially when working in dry conditions he would like to see more durable tips on the shanks, and he feels the overall machine could be a bit better built as it experienced a few bent shanks.

It is difficult to tell just by eyeballing where you think the deep tillage will do the most good. On some of his “better” fields the deep tillage produced more benefit than on other fields he thought really needed it.

Make sure you contact utility and pipeline companies to locate lines before you till. The Alberta One Call service did find abandoned pipelines at 16 inches of depth and he was working at 12 to 13 inches, so there wasn’t much leeway. †

About the author

Field Editor

Lee Hart

Lee Hart is editor of Cattleman’s Corner based in Calgary.

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