Cereal cover crops for weed suppression in a summer fallow-wheat cropping sequence

Abstract

S. M. 2000. Cereal cover crops for weed suppression in a summer fallow-wheat cropping sequence. Can. J. Plant Sci. 80: 441-449. Cropping systems in western Canada that include summer fallow can leave the soil exposed to erosion and require frequent weed control treatments. Cover crops have been used for soil conservation and to suppress weed growth. Experiments were conducted under rain-fed conditions at Lethbridge, Alberta to determine the effect of short-term fall rye (Secale cereale L.), winter wheat (Triticum aestivum L.) and annual rye cover crops in the fallow year on weed growth and subsequent wheat yield. Under favorable weather conditions fall rye was as effective as post-harvest plus early spring tillage or herbicides in spring weed control. Winter wheat and fall rye residues, after growth was terminated in June, reduced weed biomass in September by 50% compared to no cover crop in 1993 but had little effect on weeds in 1995. Fall-seeded cover crops reduced the density of dandelion (Taraxacum officinale Weber in Wiggers) and Canada thistle [Cirsium arvense (L.) Scop.] but increased the density of downy brome (Bromus tectorum L.), wild buckwheat (Polygonum convolvulus L.), and thyme-leaved spurge (Euphorbia serpyllifolia Pers.) in the following fall or spring. Wheat yields after fall rye and no cover crop were similar but yields after spring-seeded annual rye were less than after no cover crop. Spring-seeded annual rye did not adequately compete with weeds. Cover crops, unlike the no cover crop treatment, always left sufficient plant residue to protect the soil from erosion until the following wheat crop was seeded. ) et du seigle de printemps comme couvre-sol temporaire dans la sole de jachère sur la croissance des mauvaises herbes et sur les rendements subséquents du blé. Quand les conditions météorologiques sont favorables, le seigle d'automne était aussi efficace pour la maîtrise des mauvaises herbes printanières que les binages post-récolte plus les façons culturales ou l'emploi des herbicides en début de printemps. Le blé d'hiver et les restes de seigle d'automne laissés après l'interruption de la croissance en juin causaient une diminution de 50 % de la biomasse adventice en septembre par rapport aux traitements sans culture couvre-sol, mais en 1995 leur effet sur les mauvaises herbes était faible. Les couvre-sol semés en automne diminuaient la densité d'infestation du pissenlit (Taraxacum officinale Weber in Wiggers) et du chardon des champs [Cirsium arvense (L.) Scop.], mais ils provoquaient l'accroissement de la densité du brome des toits (Bromus tectorum L.), de la renouée liseron (Polygonum convolvulus L.) et de l'euphorbe à feuilles de serpolets (Euphorbia serpyllifolia Pers.) l'automne ou le printemps suivant. Le rendement du blé obtenu suivant une culture de seigle d'automne était le même qu'après une jachère nue, mais après une culture de seigle de printemps il était inférieur. Le seigle semé au printemps ne parvenait pas à soutenir la concurrence des mauvaises herbes. À la différence de...

Short-term nitrogen mineralization from warm-season cover crops in organic farming systems

“…Therefore, farming systems with long, warm growing seasons and/or dry conditions may benefit the most from utilizing warm-season cover crops which can tolerate and even thrive in these environments. In the U.S., these areas include the sub-tropical Southern region, the Great Plains drylands, and the Southwestern low desert (Creamer and Baldwin 2000;Moyer et al 2000;Wang et al 2008).…”

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

“…Fall rye (Secale cereale L.) is known to have allelopathic effects on certain weed species but not on large-seeded crop seeds such as edible beans (Phaseolus vulgaris L.; Flood and Entz 2009). In Alberta, a short-duration fall rye cover crop during the fallow phase of rotation suppressed weeds and offered soil protection, while maintaining subsequent crop yields (Moyer et al 2000). Killed mulch systems for field scale cropping using a crimper-roller are under investigation in various locations in North America (e.g., Davis 2010;Mischler et al 2010;Vaisman et al 2011).…”

Interactions between allelochemicals and the microbial community affect weed suppression following cover crop residue incorporation into soil

“…Cover crops can suppress weeds through resource and light competition (Liebman and Dyck 1993;Teasdale 1996), disruption of weed life cycles (Moyer et al 2000), physical suppression by cover crop residues (Moore et al 1994), and release of phytotoxic chemicals associated with cover crop residues (Kruidhof et al 2009;Samedani et al 2013;Teasdale et al 2012). These cover crop residueassociated allelochemicals can suppress weed seed germination (Seigler 1996), seedling establishment (Singh et al 2003;Weston 1996), and weed growth rates (Mirsky et al 2011;Wardle 1995).…”