No-till and minimum-till systems both have their advantages and drawbacks, especially when it comes to managing weeds, disease and insects in next season’s crop.
Let’s start by looking at the advantages of no-till systems. Right off the bat, they’re great for soil and moisture conservation — particularly when you’re working on lighter, sandier soils.
Growers that are direct seeding also save fuel because fewer passes are needed. Because you’re not working up and distributing soil, there’s less risk of spreading around weed seed, which may lead to fewer flushing weeds.
When we look at managing diseases, such as clubroot, no-till systems help minimize the spread of disease spores in the soil profile. You’re also not actively moving contaminated soil within or between fields.
Some drawbacks of no-till systems include potentially higher level of root disease such as common seedling root rots in cooler soil temperatures. Insects like striped and crucifer flea beetles can pose a greater threat by laying undetected in leftover straw and stubble and then feeding on canola seedlings that are slower growing in cooler, straw-covered soils.
One advantage of minimum-till systems is that you blacken the soil, which warms it up and allows you to seed sooner. Working up the top of the soil profile can provide better germination performance and faster-growing seedlings.
Keep in mind, though, that warmer soils provide weeds with a better environment to germinate. Insects also tend to gravitate to warmer soils, especially when weeds and crops are actively growing.
From a disease management standpoint, a minimum-till system lets you break down disease inoculum that can build up on heavy straw and impact next season’s crop.
Working up soil in the fall can also help with dispersing straw and creating a better seed bed for next spring. But with drier soils in the fall, the risk of spreading clubroot spores by dust is higher. That’s why any tillage of known clubroot fields (and areas where you don’t yet have clubroot) should be performed in the spring.