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Early supplies of available nitrogen to the seed-row of a canola crop as affected by fertilizer placement

Thavarajah, D., J.J. Schoenau, J.R. Bettany, G. Hultgreen, P. Qian, S.S. Mahli and R. Lemke. 2003. J. Plant Nutr. 26: 683-690


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 a canola crop. Ion exchange resin membrane probes (PRS™) 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™) 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.

Key Words

canola, N fertilization, ion-exchange membrane, mid-row band, nitrogen supply rate, PRS™-probes,side-row band