Early supplies of available nitrogen to the seed-row as affected by fertilizer placement
A field experiment was conducted at Star City, (legal location SW6-45-16-W2); Saskatchewan, Canada from May to June 2000, to measure N and P supply rates from fertilizer band to canola seed row. Ion exchange resin membrane probes (PRS™-probes) were used to measure nutrient supply rates in four treatments (80 kg/ha of urea side-band, 80 kg/ha of urea mid-row band, check/no N (side-row)/P side-banded, check/no N (mid-row)/P seed placed. The treatments were arranged in a randomized complete block design with four replications. Two anion and cation exchange resin probes (PRS™-probes) were placed in each plot in the seed-row immediately after seeding and fertilizing. The probes were allowed to remain in the field for 2 days and replaced with another set of probes every 4 days for a total of 14 days until canola emerged. Ammonium-N, nitrate-N and P supply rates were calculated based on the ion accumulated on the probes. Grain and straw yield were measured in each plot. Urea side-row band treatments had significantly higher cumulative available N supply rates than mid-row banded placement. No significant differences were observed in P supply rates. The higher N rates (120 kg N/ha) showed lower grain yield in side banding than mid-row banding treatment possibly due to seedling damage, however the earlier fluxes of N into the seed-row observed with side-banding may be an advantage at lower N rates in N deficient soils.
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