Non-Peer ReviewedA growth chamber experiment was conducted in columns to determine the availability of soil nitrogen at various depths to canola and wheat plants. Seven treatments under wet and dry watering regimes were imposed: 0-15, 15-30, 30-45, and 45-60 cm layers enriched with 15 ug g-1 (30 kg ha-1) of N and 0-30, 15-45, and 30-60 cm layers enriched with 7.5 ug g-1 (30 kg ha-1) of N (both rates as NH4NO3). Non significant differences in plant, seed, and straw mass values were observed among treatments in the irrigated wheat and canola experiments. Also, no trend in soil NO3 removal was established for the soil layers sampled at harvest for these experiments. Variability within the treatments and/or lack of nitrogen response may have masked slight yield differences imposed by the N treatments. This variability may have been imposed from differences in the amount of leachate from the columns in the irrigated experiments. The dryland wheat experiment showed significant plant and seed mass responses to N enrichment treatments. The dryland canola experiment showed significant seed yield increases to the N enrichment amendments. In both the dryland wheat and canola experiments, soil NO3 levels were very low in the 0-30 cm soil layer. This was attributed to plant removal of N from the upper soil horizons. Less variability in plant, seed, and straw mass values was observed in the dryland experiments because no leachate was collected from the soil columns
