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Abstract

Agroecosystems are one of the most heavily managed ecosystems that provide essential services
for human well being. Intense management of agroecosystems has led to global degradation of
soil and reduced biodiversity, two of the major challenges faced by agriculture today. Soil, the
foundation of an agroecosystem, forms the base for cropping systems and how it is managed
matters. My research focused on investigating how two ecologically-based soil management
techniques, cover cropping (using a species mixture of Cichorium intybus, Raphanus sativus,
Medicago sativa, Trifolium pratense, and a monoculture of Lolium multiflorum) and agromineral
amendment application (using Spanish River Carbonatite – SRC), affect both biotic and abiotic
variables such as soil nutrients, plant growth, and plant and soil invertebrate community
composition over time. My study included control greenhouse trials and trials in an operational
vineyard. In greenhouse trials, SRC was found to be especially effective for growth of
leguminous species, M. sativa and T. pratense while forb species, R. sativus and C. intybus,
tended to grow better in synthetic fertilizer. Residual effects on a second period of growth were
minimal. This suggests that, depending on species used, cover crops when combined with SRC
may be able to support an operational system in a similar way to when synthetic inputs are used.
Trials were also conducted in an operational vineyard. While the added complexity of a field
setting did not significantly affect any of the measured variables between amendment treatments,
cover crop type mattered with significantly higher vegetation-index diversity and total
abundance values found in cover crop mixture plots than in monoculture. Annual weather and
farm management practises were most likely the main driver of the variation found in soil
invertebrate community diversity. An additional experiment aimed to determine whether
Amaranthus hybridus, a known allelopathic plant species present in the vineyard, affects the
same cover crop species germination and growth using an A. hybridus tea extract treatment in
controlled conditions. Here, A. hybridus was found to inhibit germination and growth of M.
sativa and T. pratense yet stimulate growth in R. sativus and L. multiflorum. Careful
consideration should be given to which weeds can be found in an agroecosystem and how they
may influence management outcomes. Long-term investigations are needed to truly understand
how to best manage the various components found in an agroecosystem.