ONTARIO GRAIN FARMER AGRONOMY 36 been updated. “What we learned in terms of the double cropping results is that even though we have more heat units in terms of the soybean recommended variety, we actually lowered the number because those are the varieties that are yielding the best.” The figures from the 2025 test plots at the Elora Research Station indicated double-cropping is possible, albeit under ideal conditions and with the necessary adjustments in maturity group (Table 2). Row widths had less of an impact; however, seeding rate was key. Bohner determined the traditional numbers – 250,000 seeds per acre – aren’t sufficient for a location like Elora and should be increased to 263,000. “This is the real learning curve for people in the shorter heat unit areas,” he noted. “If you're going to try this, don't use an adapted variety – don’t use a variety that's even one maturity group less. The only thing you have to work on is finishing that variety, and the only hope you've got is a super short-day bean.” THE S EFFECT For years, sulphur has been the “major micronutrient”, often challenged by the absence of a reliable soil test. But Bohner discussed trial results from 2025 and a seven-year study on spring broadcast of nitrogen (21 lbs/ac actual) and sulphur (24 lbs/ac actual) from 2019 to 2025. In total, they have 49 site years, some from Pioneer Hi-Bred and Maizex Seeds, as well as OMAFA, University of Guelph and Ontario Soil and Crop Improvement Association (OSCIA). On its own, the data from nitrogen were disappointing, and the average response to 100 lbs/ ac of ammonium sulphate was 3 bu./ac. What Bohner found exciting was that 22 per cent of the trials were significant and taking an average yield response from those, there was a 10.3 bu./ac, gain, meaning fields short on sulphur could benefit greatly. Sandy, low-organic matter fields, early-planted with heavy crop residue, no sulphur applied the previous year and soil test below 5 mg/L CaCl extractable sulphur indicated a benefit. Yet the surprising secret was the presence of soybean cyst nematode (SCN). “Where there’s significant SCN, we’re seeing a better response to sulphur,” he said. “There is some scientific evidence now that SCN has a real impact on the amount of available sulphur and even more importantly, that if you have a lot of SCN, the bean needs more sulphur. There may be a reason why there’s a correlation to SCN.” • continued from page 35
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