Deep Tillage Lets Soil “Breathe” – for Sep. 6, 2010

Mark and Dennis Pashovitz figure they may have hit on a solution for soil that wasn’t producing crops to its full potential. And it’s all about air.

They had been applying a good fertility package to the grain and oilseed crops on their Perdue-area farms in central Saskatchewan, but even on better soils in years with reasonable moisture they felt yields weren’t up to snuff.

After doing some investigation and digging around in the dirt for a few seasons, the problem seemed to point toward a compaction issue. They found plants with the biggest roots and crops with higher yields were on soils that were looser, or had better tilth as some would call it.

After treating part of their farms with a low disturbance, deep tillage tool in the fall of 2009, they were convinced by August 2010 the treatment made a dramatic difference.

“We actually thought this deep tillage treatment would make the biggest difference in dry years,” says Dennis, who along with his wife Karen and young family crop about 3,500 acres northwest of Perdue (that’s about an hour west of Saskatoon). The theory is if you loosen up the soil any snowmelt or rain you do get will percolate down into the soil profile. They farm in an area where moisture is usually a limiting factor during the growing season. “We had no idea it would make such a difference in a year like this, which has been anything but dry,” he says.

PHYSICAL DIFFERENCE

The difference is not only visible in the crop, but you can feel it too. “You can see a line in the field in the crop where we did the deep tillage and where we didn’t,” says Mark, who along with his wife Ashlee and other brothers Gary and Floyd crop about 9,000 acres. “But you can also feel it under foot when you walk across the field. The untreated area of the field is hard, and when you come to the treated side it is softer. The soil has some cushion to it.”

The brothers, who farm side by side say the real proof of the treatment, which they applied to a combined 4,000 acres last fall, will hopefully reflect in the combine yield monitor when they harvest crops later this month. But, in the midst of a growing season, which dumped an unprecedented, rainforest-like 24 inches of rain on their land from May to July, they can see that deep tillage has made a difference.

The Pashovitz farms have a wide range of soil types. Mark estimates that 90 per cent of it is heavy clay loam, but there are sandy and clay mix soils as well. Some fields have rocks and some don’t. While at one time the land was farmed in a conventional tillage, crop/fallow rotation, the brothers have been continuous cropping and direct seeding most fields for five to 10 years.

Their land was showing no dramatic signs of poor productivity. “But we were applying good rates of fertility, but just didn’t seem to be getting the yields we should,” says Dennis. A standard fertilizer blend for canola included about 70 pounds of actual nitrogen, and for wheat about 55 pounds of N and about 25 pounds of phosphorus. He began doing some investigation into possible causes. Soil compaction was a possibility. Even though seeding the crops was no problem, digging down into the soil he found it quite hard. He tried applying some soil amendments designed to reduce compaction, but that didn’t produce significant improvements.

“I was looking for something that would loosen up that soil profile so roots could go down, and as research suggested, loosening up that soil would also benefit microbial activity in the soil.”

THE AGROWPLOW

The Pashovitz brothers didn’t want to till the soil and create a lot of soil disturbance, but they began looking at tools that would provide deep tillage. They came across the Agrowplow deep tillage tool ( www.agrowplow.com). Developed in Australia, and marketed in Canada for the past five years, the tillage system has shanks on 13-inch spacing which can penetrate the soil at a range of depths down to 24 inches. The shanks are actually 26 inches apart, but they are staggered in two gangs, so a shank is actually breaking the ground every 13 inches. The tool fractures the soil profile seven inches on each side of the shank, but doesn’t turn the soil over. They did a test with a 19-shank Agrowplow on the farm in the spring of 2009, and pleased with the performance, treated about 4,000 acres total on their two farms that fall.

Actually, Ashlee was the chief Agrowplow operator last fall. Starting on land right behind the combine, she used a 425-horsepower John Deere tractor to pull the deep tillage tool. It was a slow process. Travelling at four to five miles per hour, it took about 14 hours to cover a quarter section. “It gives you lots of time to listen to radio to hear what everyone else is doing on the farm,” she jokes. “The tractor was well weighted down, but I would hit areas where it was more compacted than others and it would really make the tractor work. Some areas where there had been a lot of turning with equipment would stop you dead.” Dennis used a 530-horsepower TJ New Holland tractor to pull the Agrowplow tool on his land.

While the Agrowplow shank is 24 inches long, the Pashovitzes ran it at about 15 inches deep. They identified that most of the compaction was at about 12 inches deep and ran the tip of the shank just under that to loosen the soil.

INTERIM RESULTS

So what difference did it make? While the original plan was that deep tillage would loosen and prep the soil to better store moisture when conditions were dry, it also made a significant difference under the extremely wet conditions of 2010.

On a field of Redberry lentils, for example, half the field was treated and the other half wasn’t. On the treated side, is a thick mat of robust, vibrant green lentils, while immediately adjacent on untreated land, the crop is thinner, noticeably more pale, with many yellow patches where excess moisture has either leached out nutrients, and/or denied the crop roots oxygen.

Results also appear dramatic on a late-seeded canola field, where under very wet conditions, the seed was broadcast applied with a Valmar spreader and harrowed in. No fertilizer was applied.

On the treated area the crop is waist high and flowering, with large leaves, and with plant stems the size of your little finger or larger. On the adjacent area that was seeded the same way, with the same Roundup Ready hybrid variety, the crop is at least a foot shorter, leaves are smaller, and plant stems are the size of a drinking straw or smaller. Plant roots on the treated side have a larger mass and run deeper than the roots on the untreated side.

Dennis invested about $250 in a penetrometer, a simple hand-held probe that shows on a gauge the pounds of pressure per square inch needed to push the probe into the soil. The numbers further confirmed their beliefs in several areas comparing treated to untreated soil. In many spots, on treated soil, it took only about 200 psi to push the penetrometer down two feet, while on untreated land it could take 600 psi or more to push the tool down the same depth.

While the Pashovitz brothers aren’t farming land usually considered prone to hard pan, they believe conventional farming practices over the years have contributed to a level of soil compaction that discourages root development, poor water filtration through the soil and has reduced the amount of oxygen in the soil that benefits soil microbial activity.

“We could just see when it rained, with this much water, where we used the Agrowplow the water would disappear in a day or so, and where we hadn’t used it the water would just lay there,” says Dennis. “We’ve had excessive moisture this year, but on the land where we have used the Agrowplow we are in good shape for next year even if it is dry. The moisture is down there.”

ONCE EVERY FIVE YEARS

With more of their farm to treat with the deep tillage tool, the Pashovitz brothers have now bought a larger, 29-shank Agrowplow deep tillage tool which has a 32-foot working width. It wings up on both sides for easy transport. It is the largest tool the company, with Canadian headquarters in Crossfield, Alta., has ever built. It will probably take all the power of the 530-hp tractor to pull it, but they will be able to cover more acres in a day.

Graeme Finn, manager of Agrowplow’s North American operations, says one treatment with the Agrowplow should be sufficient every four to five years depending on soil type. Finn says the company has had a lot of interest in the tool from producers in the Alberta and B. C. Peace River region because conditions have been so dry there they are looking for ways to improve soil moisture-holding capacity. “But in other parts of the Prairies this year, where too much moisture has been a problem, we are seeing where deep tillage has made a significant difference in getting that standing water off the surface and down into the soil profile.”

“I’m so impressed with what we’ve seen this year, that even if we had to use the tool every year on some fields, it would be worthwhile,” says Dennis.

Yield figures will tell the story, but Mark says the crop response should improve farm profitability. “On some crops your margin of profit is about five bushels per acre,” he says. “So if this deep tillage can add another five bushels to your yield, then you are significantly improving your bottom line.

“Direct seeding is the better way to farm, but it appears we may need some tillage just to keep that soil profile loose, and get oxygen and nutrients moving through the soil,” he says. “I think using the Agrowplow gives you the best of both worlds, you can still direct seed, but it loosens up the soil like the old conventional farming methods.”

LeeHartisafieldeditorforGrainewsin Calgary,Contacthimat403-592-1964orby emailat [email protected]

About the author

Field Editor

Lee Hart

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

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