Impact of Rate and Timing of Nitrogen Application on Seed Yield, Quality and Nitrogen Economy of Canola in Eastern Canada.

Nitrogen (N) is the most costly input in canola (Brassica napus L.) production in addition its potential negative environmental impact.  As a newly introduced crop, implementing efficient N management strategies is a prerequisite for promoting canola as a viable cash crop in eastern Canada.  A field experiment was conducted for three years on the Central Experimental Farm in Ottawa, Ontario, Canada to (1) assess the impacts of different rates of preplant and sidedress N applications on seed yield, oil and protein concentrations, and (2) determine the N use economy of canola with different indices - agronomic N use efficiency (aNUE), N uptake efficiency (NupE), N utilization efficiency (NutE) and N harvest index (NHI).  Our data show that while canola seed yields increased with increasing the amounts of N application,  all sidedressed N applications produced relatively higher yields than the equivalent preplant N application. Increasing N rates increased seed protein concentrations, but often slightly suppressed the oil concentrations.  The aNUE and NutE decreased as the amounts of N increased for all the N treatments. Sidedress N resulted in higher aNUE, NupE and higher NutE than comparative preplant N applications.  These results indicate that under humid eastern Canadian conditions, sidedress N application would be beneficial for canola production through improving the efficiency of fertilizer N use, and optimizing the seed yield and quality while sustaining the environment.

^* Corresponding Author’s Email: baoluo.ma@agr.gc.ca