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Fluid Journal : Fluid Journal 1999-2001
Spring 2000 NBPT in increasing UAN rate levels that can be side-banded with canola • Compare seedling damage and yield response to side-banded UAN at varying rates, with and without NBPT • Determine optimal UAN rates, with and without NBPT, that can be applied on contrasting soil textures. Mother nature strikes The spring of 1999 was extremely challenging. Excess rainfall throughout May and early June made seeding difficult. Our fine sandy loam site was seeded in May and the clay loam site in June. High spring rainfall caused sulfate to leach from the soil, creating a sulfur deficiency during early stages of canola growth. We broadcast 15 lbs/A of S as calcium sulfate to correct the deficiency. A July 5 hailstorm caused plant damage during early stage growth on the clay loam site. They recovered reasonably well. Harvest was also delayed due to wet, cold conditions. Seedling emergence Clay loam w/o NBPT. Significant stand reduction occurred with increasing UAN rates (Figures 1 and 2). Patterns of response were similar at two to four weeks after seeding. Stand reduction was evident at 80 lbs/A of N and increased with increasing fertilizer rate. Clay loam with NBPT. Application of NBPT reduced damage and maintained stand density at levels similar to the control, although there was a tendency to reducing stand density by increasing UAN rates at the four-week stage (Figures 1 and 2). This may reflect toxicity occurring in older seedlings as the inhibitor broke down over time. Fine sandy loam. There was no significant decrease in stand density when UAN was applied at increasing rates, with or without NBPT (Figures 3 and 4). High rainfall after seeding apparently reduced the toxicity of the N fertilizer, eliminating seedling damage. Biomass yield Clay loam. Biomass yield at flowering increased linearly with UAN applications to approximately 120-160 lbs/A of N on the clay loam soil. Fine sandy loam. N management did 200 180 160 140 120 100 80 60 40 Figure 1. Effect of N rate and NBPT on stand density at two weeks in a clay loam soil, Grant, et al., Manitoba, 1999. Stand Density (plants/yd2) 0 40 80 120 160 200 Nitrogen Rate (lbs/A) UAN UAN+UI 200 180 160 140 120 100 80 60 40 Figure 2. Effect of N rate and NBPT on stand density at four weeks in a clay loam soil, Grant, et al., Manitoba, 1999. Stand Density (plants/yd2) 0 40 80 120 160 200 Nitrogen Rate (lbs/A) UAN UAN+UI
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