High costs of fertilizer in western Canada have generated interest in alternative N sources. Legumes produce N through fixation, and may increase soil residual and mineralizable N, thus reducing the need for fertilizer N in subsequent crops. Hybrid canola (Brassica napus L.) has a high N requirement for optimum yield, but knowledge of rotational effects of legumes on canola is limited. The objective was to determine the effects of legume and non-legume preceding crops on yield and quality of canola grown the following year and malting barley (Hordeum vulgare L.) grown after canola. Field pea (Pisum sativum L.), lentil (Lens culinaris Medik.), faba bean (Vicia faba L.), canola, and wheat (Triticum aestivum L.) harvested for grain, and faba bean grown as a green manure were direct-seeded at seven locations in 2009. Canola was seeded in 2010 and barley in 2011, with fertilizer N applied at 0, 30, 60, 90, and 120 kg ha -1 . On average, all legumes, except faba bean for seed, produced higher canola and barley yields than when wheat was the preceding crop. Faba bean green manure produced the highest yields, while canola on canola produced the lowest canola yield. The legumes had little negative effect on canola oil or barley protein concentration. Yields of both crops increased with increasing N rate, but canola oil concentration decreased, and barley protein increased. The results indicate that growing legumes for seed before hybrid canola can improve canola and subsequent barley yield without negatively affecting canola oil or malting barley protein.

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M. 2009. Crop response to current and previous season applications of phosphorus as affected by crop sequence and tillage. Can. J. Plant Sci. 89: 49Á66. Field studies were conducted over a 4-yr period at two locations in western Manitoba, Canada, to evaluate the effect of phosphorus (P) fertilizer management on crop growth as affected by tillage system through a 2-yr cropping sequence. In the first phase of the cropping sequence, canola (Brassica napus L.), a non-mycorrhizal crop, and spring wheat (Triticum aestivum L.), a mycorrhizal crop, were grown under conventional (CT) and reduced (RT) systems, with 0, 11 and 22 kg P ha(1 applied as monoammonium phosphate (MAP). In the second phase of the sequence, flax (Linum usitatissimum L.) was seeded following the spring wheat or canola, with application of 0 or 11 kg P ha(1 as MAP. Phosphorus application increased the early-season biomass, P concentration, and P accumulation of canola and wheat and the seed yield of canola. Tillage system had no consistent effects on growth, P concentration or uptake, or seed yields of canola or wheat, nor were P by tillage system interactions observed. Early-season biomass production and seed yields of flax were relatively unaffected by P fertilization whether applied in the same season as flax or in the previous season, although early-season P concentration and P accumulation were increased when P fertilizer was applied to the flax. Of the factors evaluated in this study, preceding crop had the greatest influence on flax growth with flax establishment, early-season biomass, and P accumulation, and seed yield all being significantly greater when flax was seeded after wheat than after canola. Plant Sci. 89: 49Á66. Pendant quatre ans, les auteurs ont proce´de´a`des e´tudes sur le terrain, a`deux endroits de l'ouest du Manitoba, au Canada, afin d'e´valuer l'incidence des pratiques de gestion des engrais phosphate´s (P) sur la croissance de la culture, selon la me´thode de travail du sol dans le cadre d'un assolement de deux ans. Dans le premier volet de l'assolement, ils ont fait pousser du canola (Brassica napus L.), une culture sans mycorhizes, et du ble´de printemps (Triticum aestivum L.), une culture avec mycorhizes, apre`s travail classique (CT) ou travail re´duit (RT) du sol et application de 0, de 11 ou de 22 kg de P par hectare sous forme de phosphate d'ammonium diacide (MAP). Lors de la deuxie`me phase de la rotation, ils ont ensemence´du lin (Linum usitatissimum L.) apre`s le ble´ou le canola, avec application de 0 ou de 11 kg de P par hectare sous forme de MAP. L'application de phosphore accroıˆt la biomasse en de´but de saison, la concentration de P, l'accumulation de P par le canola et le ble´, et le rendement grainier du canola. La me´thode de travail du sol n'a aucun effet cohe´rent sur la croissance, la concentration de P, l'absorption de P ni le rendement grainier du canola ou du ble´; il n'existe non plus aucune interaction entre les applications d'engrais et le type de travail du sol. La production de biomasse au de...