AbstractsBiology & Animal Science

Nitrogen fertilization and nutrition of canola in eastern Canada

by Bineeta Gurung




Institution: McGill University
Department: Department of Plant Science
Degree: MS
Year: 2015
Keywords: Agriculture - Soil Science
Record ID: 2059222
Full text PDF: http://digitool.library.mcgill.ca/thesisfile130638.pdf


Abstract

Canola (B. napus) is an ideal feedstock for biodiesel production due to its high oil and low saturated fatty acid concentration. In recent years, there is a growing interest to expand canola production in Eastern Canada. Canola producers in this region lack fertilization guidelines and need appropriate N fertilizer recommendations to achieve high yields and N fertilizer use efficiency. Nitrogen (N) is a limiting nutrient in canola and plays a determinant role in improving oilseed yield and quality. The objective of this study was to evaluate the status of canola N in relation to soil N mineralization and nitrification and microbial biomass N (MBN) at three sites in Eastern Canada. Experimental sites were located in Ste. Anne-de-Bellevue (Quebec), St. Augustin-de-Desmaures (Quebec) and Ottawa (Ontario). During 2012, the experiment was designed as a randomized complete block with four pre-plant N fertilizer treatments (0, 50, 100 and 150 kg N ha-1 from urea), replicated four times. Canola biomass and N concentration were assessed at four growth stages namely rosette, 20% flowering, 80% pod formation and 90% maturity. Soil N pools (NH4, NO3, MBN, net N mineralization rate and net nitrification rates) were also determined at stages. Canola N concentration was greater with 100 kg N ha-1 than at 0 kg N ha-1 at the rosette stage (P<0.001) in Ste. Anne-de-Bellevue and flowering stage (P<0.005) in St. Augustin-de-Desmaures, but by maturity there was no difference among N fertilizer treatments. Net N mineralization and nitrification rates as well as MBN concentration varied significantly (P<0.001) with canola growth stage, but this was not affected by N fertilization, suggesting that the soil N supply was derived from decomposition of organic residues by the activity of a relatively stable microbial population. At the end of the growing season, the NO3 concentration was elevated in plots that received 150 kg N ha-1 indicating that canola did not utilize all of the N in the soil and so did not benefit from fertilization. This residual soil NO3 represents economic inefficiency and pose environmental risk. Future research on seed yield and harvest index (HI) under the climatic conditions of Eastern Canada will contribute to the development of a precise N fertilization guideline. Le canola (B. napus) est une matière première idéale pour la production de biodiesel en raison de sa teneur élevée en huile et sa concentration faible en acides gras saturés. Au cours des dernières années, il y a un intérêt croissant pour accroître sa production dans l'Est du Canada. Cependant, les producteurs de canola dans cette région n'ont pas encore de formulations d'application d'engrais azotés et il est nécessaire d'avoir des recommandations appropriées pour atteindre des rendements élevés et l'efficience de l'utilisation de l'azote. L'azote (N) constitue un facteur limitant pour le canola et l'élément nutritif déterminant pour améliorer les rendements et la qualité des oléagineux. L'objectif de cette étude est d'évaluer le statut de N dans le…