IMPROVING SOIL MOISTURE RETENTION IN HAZELNUT ORCHARDS THROUGH THE USE OF NATIVE COVER CROPS AND CONVENTIONAL MECHANICAL TREATMENTS
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Date
2020-12
Authors
MARISSA, LANE-MASSEE
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
The purpose of this study is to understand how hazelnut orchards in the Willamette Valley,
Oregon retain soil moisture throughout the spring and summer months, and how orchard floor treatments
can be used to improve soil moisture retention in vruious ages of hazelnut orchards. The two orchru·d floor
treatments studied looked at how the conventional mechanical processes of flailing and scraping impact
soil moisture retention, and how the use of native cover crops can be used as a way to increase soil
moisture retention. The mechanical methods of treatment include inigation, flailing, scraping, and many
hruvesting processes, and the vegetation treatment methods includes seeding mixes of native and
agricultural cover crops. The methods of data collection in the study consist of soil moisture monitoring
and vegetation community analysis. The results dete1mined in this study conclude that both mechanical
and vegetative treatments have a wide vru·iety of impact on soil moisture retention in hazelnut orchards in
the Willamette Valley. Results vruy dependant on orchru·d canopy cover, orchru·d age, and vegetative
community composition. Canopy cover had the lru·gest impact on soil moisture retention and flower
development in vegetative communities. Orchards with less canopy cover saw a greater po1t ion of native
cover smvive to matmity and/or produce seeds, but retained less soil moisture than orchru·ds with more
canopy cover. These orchards saw a greater smvival rate of all native seed mixes, especially the growth
and flowe1ing of the annual communities. Orchards with more canopy cover did not see lru·ge po1tions of
smviving vegetation, but retained soil moisture more than orchards with canopy openings. In these
orchards, most annuals did not smvive, but the perennial communities saw successful rates of
smvivorship from sunlight competition and repeated mechanical disturbance. Overall, the vegetative
communities that were composed of native plants, combined with less invasive mechanical treatments,
retained the highest amount of soil moisture throughout the study pe1iod. The moisture retention rate in
these plots averaged a 3-5% increase compru·ed to those plots in which vegetation was non-native or
non-seeded, or the scraping mechanical treatment. This study has the great possibility to impact how
many hazelnut frumers prepare their orchard floors for hruvest, how agricultural systems in the
Willamette Valley can reintroduce impo1tant ecosystem se1vices like biodiversity, wildlife habitat, and
soil moisture retention, and increase the potential to alleviate the impacts of anthropogenic climate change
on agricultural crops like hazelnuts.
Description
19 pages