12 Like Us on Facebook: BetterFarmingON Better Farming | June/July 2024 If you can’t beat them, crowd them out! That’s the wisdom from a new meta-analysis on the effect of narrow rows in corn and soybeans on weed control. The study, authored by a multi-state team of researchers led by University of Nebraska weed scientist Dr. Amit Jhala and graduate student Mandeep Singh, examined 35 studies from 12 states between 1961 and 2018. The researchers came to a pretty clear conclusion: Narrow rows (less than 30 inches wide) suppressed weed density, size (biomass), and weed seed production, and bumped yields up, but only in soybeans. “Overall, results suggest that narrow row spacing can potentially be used as an integrated weed management tool in combination with herbicides in soybeans for the management of herbicide-resistant weeds,” the researchers concluded. Soybeans canopy faster The study’s results are largely focused on soybeans, which accounted for nearly 80 per cent of the studies the researchers examined. In narrow rows, soybeans canopy faster, stealing precious sunlight from their weedy interlopers between the rows. So, while it’s not terribly surprising that the practice would suppress weeds overall, the numbers the researchers uncovered were eye-opening. Within narrow-row soybean fields, on average, the density of weed populations thinned out by up to 42 per cent, and weed size (or biomass) shrank up to 71 per cent. Weed seed production also fell by 45 per cent on average. Fields with multiple applications of herbicides and 7.5-inch rows showed the most statistically significant drops in weed seed production, the researchers noted. Soybean yield also fared well in narrow rows, with the researchers finding an average increase of 12 per cent across the studies they examined. Narrow rows can also help buy time in the spring to manage emerged weeds. Past research has found that the “critical time for weed control,” meaning the time when weeds can be removed before they affect yield, comes earlier in wide-row bean fields around the V1 growth stage. In contrast, in narrow-row fields, farmers had until the V2 to V3 growth stage to control weeds with herbicide passes before the yield loss became permanent. Narrow rows pair well with other integrated weed management tactics, such as cover crop residue. Fewer solid conclusions could be drawn for corn, in large part because the researchers found only six studies that examined the effect of narrow row spacing in corn fields. The difference between row spacing in those selected corn studies was also less pronounced than in the soybean studies, where row space options ranged from 30 inches to as low as 7.5 inches. As a result, meaningful differences in light interception between the smaller range of corn row spacing likely wasn’t observed, the researchers noted. BF Research NARROW ROWS ARE A WEED-CONTROL WIN Research finds benefits to decreasing soybean row width. By Emily Unglesbee, GROW (Getting Rid of Weeds) Narrow-row soybean fields saw the density of weed populations thinned out by 42 per cent. Emily Croft photo … the top producers across Ontario for just PENNIES per adult reader! Paul.Nolan@Farms.com ADVERTISERS REACH ...
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