A wet harvest has left farmers in many areas of Western Canada considering options for addressing soil compaction. One of the options that’s seen increased interest in recent years is the use of cover crops, specifically radishes, to break up root-restricting compacted soil.
“Radishes are a cover crop that are being sold specifically for compaction alleviation. You see that in a lot of the names that are given to radish cover crops,” notes Yvonne Lawley, plant science professor and researcher at the University of Manitoba. Prior to joining the U of M, Lawley focused on cover crops while completing her PhD at the University of Maryland — one of the leading cover crop research institutions in North America.
As she explains in this Canola School episode, there are two steps in the process of alleviating compaction with cover crops: ‘biodrilling’ and decomposition.
Read more: Canola School — Fixing Harvest Ruts
One of the reasons there’s been strong interest in radishes is they’re known for their biodrilling ability — their roots are better than some other cover crops at pushing through root restricting layers, explains Lawley.
“We often think about this big radish root…but it’s not that part of the radish root that’s doing the really hard work of alleviating soil compaction,” she points out. “It’s the fine root hairs that are actually the mechanism or the means that plants use to alleviate soil compaction.”
And it’s when those roots decompose that they leave behind channels to help subsequent crops grow through the root-restricting layer and improve water infiltration from on the soil surface, explains Lawley, as long as those pathways aren’t disturbed by intensive tillage. A well-aggregated soil is also better at withstanding traffic on top of it, she notes.
As part of a soil compaction workshop co-hosted by the Manitoba Canola Growers in Portage, Man., Lawley discussed the targeted goals when using radishes to address compaction, what this means for tillage practices, considerations when planting another brassica into a canola rotation, and more: