• Exploring Diversified Vineyard Ecological Soil Management Strategies: Impacts of cover cropping, Spanish River Carbonatite, and smooth pigweed (Amaranthus hybridus) interactions on an agroecosystem

      VanVolkenburg, Heather; Department of Biological Sciences
      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.