Diversity - Intensity of Cover Crop Systems: Managing Weed Seed Bank - Soil Health

Diversity - Intensity of Cover Crop Systems: Managing Weed Seed Bank - Soil Health

Summary

This project aims to look at two related issues on low-input and organic small-scale diversified vegetable farms: recurrent and ubiquitous weed problems, and the need for long term soil improvement. Cover crop species and the frequency, timing, and depth of soil disturbance can affect soil quality and contribute to weed management by imposing stresses at multiple points in weed life cycles. Different cover cropping strategies are being investigated with simultaneous goals being the depletion of the weed seed bank and the maintenance or improvement in soil health. Cover cropping practices that can address these issues are critical to sustain production without herbicides, and are needed if reliance on cultivation is to be reduced or eliminated.

Objectives/Performance Targets

• ∑ Experiment Station and on-farm research will yield a decision-aid matrix including weed species or functional groups, timing and intensity of disturbances, and diversity of cover crops deployed; management strategies will be identified based on their ability to reduce the germinable portion of the weed seed bank while maintaining or improving soil health.
  ∑ Fifteen farmers will implement intensified/diversified cover cropping strategies on particular fields to reduce the seed bank of problematic weed species.

Accomplishments/Milestones

The main research component of this grant is a field study at the University of Maine Rogers Farm which was established in 2001 to compare the following four vegetable/cover cropping systems: (1) Conventional system is a conventionally-managed 2-year rotation of broccoli and winter squash; (2) Beach Hill system an organic, “land limited” system, also a 2-year rotation of broccoli and winter squash, but with winter cover crops (e.g. rye/hairy vetch) planted following harvest of the cash crops; (3) New Leaf system an organic, 4-year rotation of broccoli, winter squash, cereal/red clover, red clover sod; and (4) Nordell system an organic, 4-year rotation of broccoli, cover crop/summer fallow/cover crop, winter squash, cover crop/summer fallow/cover crop.
In separate satellite trials three varieties of brassicas and an oat control were planted as green manures in the year preceding early or “new” potatoes to test the biofumicant properties of incorporated brassicas. Tuber quality, yield and weed pressure will be measured in next year’s potato crop. This trial was replicated at five sites throughout Maine, including two university experiment stations and three mixed vegetable farms.
Outreach efforts were expended this past field season with project participants giving a total of 16 presentations at which approximately 400 people attended (See Appendix 1). These presentations covered many aspects of cover cropping, weed control and soil quality. Trials demonstrating different cover-cropping strategies were also planted at three sites including; the University of Maine’s Rogers Farm in Old Town and Highmoor farm in Monmouth, and at the Maine Organic Farmers and Gardeners Association’s Common Ground Fair site in Unity. These cover crop trials were used alone or in conjunction with the experimental plots as visual aids in many of the presentations.

Collaborators: