Variable N fertility management of canola at the field scale, based on analysis of yield maps and spatial and statistical variability of soil test N and P

Response of canola yield to fertilizer has often been attributed to variability of terrain attributes such as catchment area. Research was conducted with producer’s field-scale equipment in Alberta, Saskatchewan and Manitoba during 2014 and 2015. Seven fields were seeded to canola in 2014, and nine in 2015. Randomized fertilizer treatments (0, 50, 100 and 150% of soil test recommendations for N) with 4 replicates were located in low, average and high producing zones based on analysis of 3 to 5 years of yield maps. Canola yield in 2014 and 2015 generally increased with fertilizer N in analyses of all fields combined for 2014, and varied between low, average and high zones, though these trends were not significant and there was considerable variability between fields. The variability of canola yield due to terrain attributes was assessed in relation to management zones based on historical yield and fertilizer management. Terrain attributes such as channel network base, modified catchment area and catchment slope accounted for variability in canola yield, but these relationships were not consistent for all farms. Analysis and variable management will require analysis of terrain attributes for each field to adequately assess variables which influence fertilizer response.