Symbiosis in cover crop

Cover cropping serves multiple functions in agroecosystem sustainability at the UBC farm and the Orchard Garden. They provide habitat and forage for beneficial insects and soil organisms, and increase overall plant diversity. They can also be habitat and forage for migratory birds improving ecosystem diversity. Cover crops provide organic matter and nutrients to the soil, protect soil from erosion, stablizes soil, and suppress weeds once established.

The UBC Farm and the Orchard Garden utilize a diverse legume-grass cover crop program. Grass and cereal grains, including annual ryegrass, spring barley, winter rye, winter wheat and buckwheat are intercropped with legumes like fava bean, hairy vetch, field pea, crimson clover, and white clover (Johnson, A. et al). Many of these cover crop species form symbiosis with soil organisms such as the rhizobium bacteria and arbuscular mycorrhizae fungi.

Benefits

The inherently low nutrient holding capacity of UBC farm soil initiates further investigation into optimizing nutrient flow. The symbiotic relationships of various cover crop species with Rhizobium and Arbuscular Mycorrhizal Fungi (AMF) serve to optimize nutrient uptake and store vegetative biomass. Cover crop residues incorporated into the surface soil and act as green manure and mulch for the subsequent cash crop. For our purposes here, we will focus on the symbiotic relationship developed through inoculation of legume species with Rhizobium  to enhance nitrogen fixation and provide extra nitrogen to the system in situ as well as through decomposition and mineralization of plant residues. We will also investigate the Mycorrhizal associations with cover crops at the UBC farm and Orchard Garden, indicating enhanced nutrient cycling.

Goal

This project aims to confirm the presence of Rhizobium and Arbuscular Mycorrhizal Fungi (AMF) associations with the cover crops at UBC farm and the Orchard Garden. From our assessment we may offer suggestions to the farm and garden management teams for ways to improve this valuable symbiotic relationship.

Objectives

At the UBC farm and the Orchard Garden