Suitability of legume cover crop-winter wheat intercrops on the semi-arid Canadian Prairies

Abstract

. 2010. Suitability of legume cover crop-winter wheat intercrops on the semiarid Canadian prairies. Can. J. Plant Sci. 90: 479Á488. Farmers on the Canadian prairies are interested in including legume cover crops in their cropping systems to reduce fertilizer inputs and improve farm sustainability. A field study was conducted to determine the merits of establishing alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.) or Austrian winter pea (Pisum sativum L.) cover crops in fall or in spring with winter wheat (Triticum aestivum L.). Springplanted legumes emerged well within the winter wheat crop, but their growth was limited under these semi-arid conditions. Fall-planted red clover had low plant densities following winter in two of three experiments and fall-planted winter pea reduced winter wheat yield by 23 to 37% compared with the no cover crop control. In contrast, fall-planted alfalfa exhibited good winterhardiness, provided some weed suppression without reducing winter wheat yield, caused only a slight reduction in soil water content, and contributed an extra 18 to 20 kg ha(1 of available soil N at the time of seeding the following spring crop. Additionally, fall-planted alfalfa increased the yield of succeeding canola (Brassica napus L.) in unfertilized plots in two of three experiments. Further research is warranted to better understand the agronomic and economic benefits of alfalfa-winter wheat intercrops under a wider range of environmental conditions.Key words: Cover crops, intercropping, relay crops, soil nitrogen, soil conservation Blackshaw, R. E., Molnar, L. J. et Moyer, J. R. 2010. Utilite´d'une culture intercalaire de ble´d'hiver double´e d'une cultureabri de le´gumineuse dans la zone mi-aride des Prairies canadiennes. Can. J. Plant Sci. 90: 479Á488. Les agriculteurs des Prairies canadiennes aimeraient inclure des cultures-abris de le´gumineuses a`leurs syste`mes de production afin de diminuer la quantite´d'engrais qu'ils utilisent et de rehausser la durabilite´de leur exploitation. Les auteurs ont effectue´une e´tude sur le terrain en vue de de´terminer l'utilite´d'une culture-abri de luzerne (Medicago sativa L.), de tre`fle rouge (Trifolium pratense L.) ou de pois d'hiver autrichien (Pisum sativum L.) seme´e a`l'automne ou au printemps avec du ble´d'hiver (Triticum aestivum L.). Les le´gumineuses seme´es au printemps le`vent bien dans le ble´d'hiver, mais les conditions mi-arides en freinent la croissance. Dans deux essais sur trois, le tre`fle rouge seme´a`l'automne a donne´un peuplement de faible densite´apre`s l'hiver, alors que le pois d'hiver plante´a`l'automne a re´duit le rendement du ble´d'hiver de 23 a`37 %, comparativement a`la parcelle te´moin, sans culture-abri. En revanche, la luzerne seme´e a`l'automne re´siste bien a`l'hiver, concourt a`la suppression de quelques mauvaises herbes sans pour autant re´duire le rendement du ble´d'hiver, n'entraıˆne qu'une le´ge`re baisse de la teneur en eau du sol et ajoute 18 a`20 kg de N disponible par hectare au sol aux semis, le print...

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…Yield benefits to the subsequent crop were observed in all studies in treatments where legumes established and grew successfully. Blackshaw et al (2010) also observed weed suppression by the alfalfa cover crop.…”

“…In Alberta, red clover, alfalfa, and winter pea (Pisum sativum L.) were established successfully with winter cereals in both fall and spring plantings (Blackshaw et al 2010). In all these studies, biomass production by cover crops varied widely, ranging from near 0 to over 4000 kg ha (1 .…”

“…Studies in Manitoba and Alberta have reported reduced soil moisture following productive cover crops Kahimba et al 2008;Blackshaw et al 2010). Soil water depletion by the cover crop can be a detriment in dry climates and a benefit in wet climates.…”

The Sustainability of Organic Grain Production on the Canadian Prairies—A Review

“…There have been a number of integrated weed management studies in south-central Alberta incorporating cover crops, underseeding and green manures [35][36][37][38][39]. While all of these studies included some form of chemical management in the protocol, all related their work to potential for organic systems.…”

“…The authors suggest that some of the weed suppression effect of sweetclover may have been due to allelopathic compounds. Alfalfa, red clover, or Austrian winter pea were grown as spring or winter planted cover crops in dryland systems of the western Prairies [37]. Spring planted legumes exhibited limited growth, and there were some problems associated with winter kill, crop yield suppression and/or weed control, with all cover crops except alfalfa.…”