There’s crop rotation, herbicide rotation and now Marla Riekman is advocating for tillage rotation.
“There is the idea of rotational tillage where you can use some of your tillage options and use them in the most appropriate spots in your crop rotation,” Manitoba Agriculture’s soil management specialist said in an interview Sept. 7.
Riekman isn’t getting a lot of calls about burning crop residue, but farmers are calling about tillage.
New ways of working the soil, such as vertical tillage, along with improved straw choppers and shorter-strawed wheat varieties have helped farmers better manage crop residue. Less burning is a good thing, but some forms of tillage are worrisome, she said.
Vertical tillage discs chop residue into smaller pieces to assist in breaking it down. But turn those discs slightly and it’s “vertical tillage on steroids,” she said.
“They are very useful in certain parts of your crop rotation,” Riekman said. “Where I get worried is if they get used on every acre, every year.
“Use those more aggressive tools on the heavy crop residue fields — the ones that really need it — don’t use it on your soybean field. Rotate through your different tillage implements along with your different crops so you’re not hitting every acre, every year with the same implement.”
Faster tillage moves more soil and causes more variability. That can result in tillage erosion, especially on sloped terrain, she said.
“Using high-speed shallow discs, or high-speed tillage in general, is not a good idea because it will strip more soil off the top and down the hill,” Riekman said. “Greater variability means you pull more soil downhill than you pull back up.”
Shallow discs that work the soil just two inches deep are increasingly used on moist or wet soils because the risk of getting stuck is reduced, she said. But it can also lead to soil compaction, making it harder for water and roots to go down.
“That’s why I really want people to consider rotating their depth (of tillage) over time,” Riekman said. “If you’re going to till, mix it up… pun intended.”
Shallow discs make a fluffy seedbed, but two inches down the soil can get too firm.
“This spring we saw a lot of these fields blow,” she said. “The seedbed is beautiful but the problem is that soil had an easier time blowing away and in some cases it even exposed this hardpan layer two inches down with the seed laying there in patches across the field.”