Student Projects in Organic Agriculture

Researchers: Les Eccles, Karen Maitland, Dean Louttit, and E. Ann Clark, Plant Agriculture, University of Guelph

Abstract: Grain yield and weed responses to 4 oat cultivars, each sown at 4 rates of seeding, both drilled and broadcast, were examined in 2002 and 2003 at the Ignatius Jesuit Centre (IJC) near Guelph, ON. The IJC site offered transitional and then certified organic land to support this study. Growth and yield differed greatly between years due to site differences in weed populations and to differences in date of seeding. The 2002 seeding was delayed by 4 weeks, compared to 2003, owing to a late, wet spring. As a result, mean weed biomass was nearly 3X higher in 2002 (1470 vs. 520 kg ha^-1), while oat grain yield was 63% higher in 2003 (3592 vs. 2208 kg ha^-1, respectively). Oat cultivar significantly affected grain yield in both years, with IDA consistently highest and AC Rigodon consistently lowest yielding (means of 3352 vs. 2621 kg ha^-1, respectively), but had no effect on weed biomass. Cultivars did not interact with years, showing wide adaptation for grain yield, regardless of weediness or date of planting. Increasing rate of seeding above the recommended level of 250 plants m^-2 (100 kg seed ha^-1) to 450 plants m^-2 (180 kg seed ha^-1) did not significantly increase yield but reduced weed biomass by an average of 41%. Thus, higher seeding rates may have carry-on advantages in reducing future weed pressure. Drilling seed significantly increased yield and reduced weed biomass in both years, as compared to broadcasting. Broadcast seed did not emerge as quickly or as uniformly due to poor seed distribution/placement, and poor seed to soil contact. A third year of testing is underway in 2004 adding date of seeding as a treatment variable.

Funding Source: OMAF Contract; Organic Advocates; Ontario Work-Study Program; HDRC Summer Career Placement; University Research Assistantship; seed supplied by Cribit Seeds, OntarBio, and Hyland Seeds.