Enhancing the Competitive Ability of Organic Oat (Avena sativa L.) Cropping Systems

D. I. D. S. Benaragama and S. J. Shirtliffe

Abstract
Effective weed management strategies are limited in organic oat cultivations as herbicide use is prohibited. Enhancing the crop competitive ability by integrating both cultural and mechanical weed control methods is a key strategy in managing weeds in such instances. Yet the relative efficacy of different strategies and their interactions when combined is not well known.

The objectives of this research were, to develop a competitive organic oat cropping system integrating both cultural and mechanical weed control techniques. Four cultural practices, two oat genotypes, CDC Baler (competitive) and Ronald (less competitive), two planting densities (250, 500 plants m^-2), two row spacings (11.5, 23 cm), and post-emergence weed harrowing were factorialy applied to two organically managed oat fields in 2008 and 2009 in Saskatoon, Saskatchewan.

The results indicated that doubling the seeding rates significantly (P < 0.05) increased the grain yield by 10.7% and reduced the weed biomass (P < 0.001) by 41%. The competitive oat genotype CDC Baler was more weed suppressive (P < 0.05) than Ronald. Post-emergence harrowing increased (P < 0.01) the grain yield by 13% compared to the non harrowed control. On the other hand, harrowing reduced (P < 0.001) the weed density on 3 of the 4 site years tested. Importantly there were no interactions identified except for weed biomass where harrowing on high crop density planting were the most effective (P = 0.07).

The results clearly indicated that increasing crop density and post-emergence weed harrowing was the most effective strategy in weed control. This highlights the importance of integrating both cultural and mechanical weed management practices over the use of individual practices to manage weeds in organic cropping systems.


Source
Proceedings of the Joint Conference of the Canadian Society of Soil Science and the Canadian Society of Agronomy, Beyond Organics session. Saskatoon, Saskatchewan. 20-24 June 2010.


Author Locations and Affiliations
Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK


Posted July 2010