A few months back, Ohio State University agronomists produced a website article suggesting that no-tillers consider limited tillage. They felt numerous concerns with soil damage, weed control and disease pathogens and insects that survive on crop residue could be remedied with light tillage.
In another area of the world, Australia no-tillers are facing severe weed resistance worries. Among a few growers and educators, there’s the thought that a light tillage pass may be the most cost-effective way of controlling hard-to-kill troublesome weeds.
Australian Weed Concerns
As reported on Australia’s Grain Central website, the country’s no-till acreage peaked around 2005 with 93% of their grain crops being no-tilled. Since then, the Grains Research and Development Corp. estimates the country’s no-till acres have declined. Some 25% of growers used some tillage in 2016, with nearly three-quarters doing it to control weeds.
The move by no-tillers toward limited tillage is a short-term compromise to control problem weeds, says James Hagan. The ag economist at the Queensland Department of Agriculture and Fisheries says growers are not going to revert back to full tillage. Instead, they see it as a one-off tillage step before going back to no-till.
Evaluating Choices
With heavy weed pressures, Hagan says it’s sometimes more cost effective to make an occasional tillage trip than to rely on intensive herbicide applications. In some instances, limited tillage can replace as many as eight herbicide applications a year to clean up intensive weed control concerns.
Research has shown the challenge of relying only on herbicides for controlling wild radish. At first, it was easy to control this weed with low-cost herbicides, but it became a different story when weed numbers dramatically increased and resistance developed.
While a no-till trial in central Queensland showed herbicides gave only minimal control of problem weeds, combining light tillage with herbicides gave 95% control of wild radish and ryegrass.
Fortunately, North American no-tillers haven’t yet had the serious weed and resistance issues that are a major concern in Australia. Unlike the suggestions in the Ohio report, let’s hope we can solve any serious weed concerns without the need for moving back to even limited amounts of tillage. No-till offers too many economic and environmental benefits we don’t want to lose.
