Early Supplies of Available Nitrogen to Seed?Row of a Canola Crop as Affected by Fertilizer Placement

A field experiment was conducted at Star City (legal location SW6-45-16-W2); Saskatchewan, Canada from May 2000 to June 2000, to measure nitrogen (N) and phosphorus (P) supply rates from fertilizer bands to the seed-row of canola crop. Ion exchange resin membrane probes (PRS(TM)) were used to measure N and P supply rates in four treatments [80 kg N ha(-1) of urea as side-row band, 80 kg N ha(-1) of urea as mid-row band, check/no N (side-row)/P side-row, check/no N (mid-row)/seed placed P]. The treatments were arranged in a randomized complete block design with four replications. Two anion and cation exchange resin probes (PRS(TM)) 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. Urea side-row band treatments (fertilizer N 2.5 cm to side of every seed-row) had significantly higher cumulative available N supply rates than mid-row band placement in which fertilizer N was placed 10 cm from the seed-row in between every second seed-row. No significant differences were observed in P supply rates. The higher N rates (120 kg N ha(-1)) resulted in lower grain yield in side-row banding than mid-row banding possibly due to seedling damage. However, the earlier fluxes of N into the seed-row observed with side-row banding may be an advantage at lower N rates in N deficient soils.