Yield and Weed Suppression of Crop Mixtures in Organic and Conventional Systems of the Western Canadian Prairie

Abstract

To investigate intercropping as a management strategy to increase crop productivity and weed suppression in organic systems, spring wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), canola (Brassica napus L.) and fi eld pea (Pisum sativum L.) monocultures were compared with two-, three-, and four-crop intercrops containing wheat at two organic and one conventional site in 2006 and 2007, central Alberta, Canada. We measured crop and weed biomass, grain yield, and crop competitiveness against weeds from a replacement design in a completely randomized block experiment. Pea and canola monocrops on organic sites yielded the least of all crop treatments. Conventional crop treatments generally yielded higher than organic treatments. Few land equivalent ratios (LERs) on organic sites were signifi cantly >1.0. Some wheat intercrops without barley showed overyielding (LER > 1.0) potential. Most of the signifi cant LERs were from three-and four-crop intercrops. More than 50% of the intercrops on organic sites signifi cantly suppressed weeds (based on relative weed biomass) and most of these intercrops had barley in the mixture. Barley as a sole crop and in intercrops suppressed weeds better than all other intercrops and sole crops. Th e wheatcanola intercrop exhibited the best weed suppression of the two-crop intercrops on organic and conventional sites. Th e crop densities used in this study may have contributed to the extremely low pea and canola monocrop yields as well as low LERs. Due to this, our fi ndings should be regarded as showing trends and potential from intercrops only. We therefore recommend further studies to establish ideal densities for the intercrops used.

Effects of Cutting Phenology (Non-dormant Versus Dormant) on Early Growth Performance of Three Willow Clones Grown Under Different Weed Treatments and Planting Dates

“…This is likely due to the declining carbohydrate reserves of nondormant cuttings later in the season. However, as WSA and WT are simple proportions between biomass of crop (in our case willow) and weed (in our case spring barley) grown in mixtures and in monocultures [25,26], levels of WSA and WT also may be influenced by other factors than direct cropweed interactions. Influence of organisms from other tropic ) from non-dormant and dormant willow cuttings grown with and without weeds planted at five different dates.…”

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

“…There is limited documented research work on grain intercropping in the NGP and the results of this research are inconsistent. Overyielding and greater yield stability have been observed in some crop combinations and under some conditions, but not in others (Carr et al 1995(Carr et al , 2004Szumigalski and van Acker 2005;Kaut et al 2008;Pridham and Entz 2008;Hummel et al 2009;Nelson et al 2012).…”

“…In spite of a lack of clear evidence for increased yield, many studies report other benefits such as weed suppression (Carr et al 1995;Szumigalski and van Acker 2005;Pridham and Entz 2008;Nelson et al 2012), lower levels of plant disease (Vilich-Meller 1992;Jensen et al 2005;Pridham and Entz 2008;Hummel et al 2009), enhanced nutrient cycling (Szumigalski and van Acker 2006), and enhanced seed quality (Hummel et al 2009). Positive effects of intercropping on insect populations have not been observed in research from the prairie region (Weiss et al 1994;Butts et al 2003;Hummel et al 2009).…”

Weed Control in Maize with Gliricidia Intercropping

“…Several studies have shown that intercropping reduces wealth, infestation, density and growth of weeds in relation to monocropping (Ibeawuchi et al, 2005;Agegnehu et al, 2008;Nelson et al, 2012). In some of these studies, intercropping has provided economic benefit and weed control (Agegnehu et al, 2008).…”

“…In some of these studies, intercropping has provided economic benefit and weed control (Agegnehu et al, 2008). In others, there was a reduction of the infestation, but there was no benefit of intercropping in relation to monocropping (Nelson et al, 2012). Ibeawuchi et al (2005) have found that the most productive intercroppings were the ones that least controlled weeds and vice versa.…”