Date of Award

Summer 8-2018

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Eric Gallandt

Second Committee Member

Ellen Mallory

Third Committee Member

Gregory Porter

Abstract

Weeds remain the foremost production challenge for organic small grain growers in the Northeastern United States. Instead of sowing crops in narrow, single-line rows, band-sowing with inter-band hoeing is a cropping strategy that could provide superior weed control. In theory, band-sowing suppresses weeds in the intra-band zone by improving the spatial arrangement of the crop from that of typical rows to a more uniform pattern within the planted bands, maximizing interspecific and reducing intraspecific competition. Weeds in the inter-band zone are controlled by cultivating with aggressive sweeps; tine harrowing can target weeds in the intra- and inter-band zones.

Chapter one addresses field experiments performed in Maine and Vermont in 2016 and 2017 to evaluate band-sowing for its ability to control weeds and enhance yields in spring barley (Hordeum vulgare L. ‘Newdale’). Five treatments were compared: the region’s standard practice for growing organic cereals, narrow-row high density planting, wide-row planting with inter-row hoeing, band-sowing without inter-band hoeing, and band-sowing with inter-band hoeing. Mustard (Sinapsis alba L. ‘Ida Gold’) was sown uniformly throughout the experiment as a surrogate weed. Band-sowing with inter-band hoeing reduced surrogate weed density on average by 48% from the standard practice, however, the effect on weed biomass was inconsistent. Suboptimal timing of hoeing, and adverse weather conditions may have contributed to the lack of consistent treatment effects. Optimization of band-sowing is likely possible, and it is recommended that band-sowing be further investigated prior to advocating its use to organic cereal growers.

Chapter two addresses field experiments performed in Maine in 2016 and 2017 that compared two treatments: band-sowing with inter-row hoeing, and the region’s standard practice. Treatment effects on weeds and yield were evaluated in multiple grain crops: spring wheat (Triticum aestivum L. ‘Glenn’), oat (Avena sativa L. ‘Colt’), field pea (Pisum sativum L. ‘Jetset’), and flax (Linum usitatissimum L. ‘Prairie Thunder’). Band-sowing improved weed control from the standard practice, however, crops with greater competitive ability (wheat and oat) performed superior to less competitive crops (field pea and flax). Throughout, yields were unaffected by treatment, exceptions being: band-sowing increased oat yield by 6%, and decreased field pea yield by 35% in separate years.

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