Crop Rotations For Soil-Building And Weed Control: The First 12 Years Of Glenlea

Martin Entz, University of Manitoba, Winnipeg MB

The Glenlea project represents a paradigm shift, from product to process research. It was initiated in 1992 near Winnipeg, MB and has run through 3 cycles of its 4 year rotations. Rotations include a grain system, a green manure system and a forage system, and share flax as the year 4 test crop. Each rotation is run under organic conditions, conventional conditions, and also in systems with either herbicide but no fertilizer or fertilizer but no herbicide.

In the first two cycles, flax yields in organic forage were near to those in conventional systems. Yields could be maintained by appropriate rotations. By the third cycle, weeds, especially wild mustard, in the organic forage had increased such that an additional measure, delayed seeding, was necessary to retain high yields. Flax profitability in the organic forage with late seeding near tripled that of conventional flax.

The Glenlea rotation study has been a home for many additional projects. Biodiversity, as indicated by carabid beetles, was highest in the organic grain rotations. Nutrient levels were followed. With the right rotation, organic systems could build nitrogen, but phosphorous levels were depleting, especially in the organic forage rotation. Micronutrients were higher in organic systems, and mycorrhizal colonization of flax was higher. In terms of environment, the organic system used approximately 40% of the energy, and produced 40% of the carbon emissions of the conventional system.

The Glenlea project continues, with increased emphasis on plant diversity, weed management, and nitrogen and phosphorous fertility.

Contact Info:
Martin Entz, Department of Plant Science, University of Manitoba Winnipeg, Manitoba, R3T 2N2 CANADA
email: m_entz@umanitoba.ca