Thursday 18 December 2014

Sustainable Urban Agriculture: Research and Outreach

Permaculture Research Institute of Saskatchewan (PRI SK) in collaboration with the Garden Patch and Let’s Talk Science: an EcoFriendly Sask Action Grant 

Permaculture Research Institute of Saskatchewan, in collaboration with the Garden Patch - Saskatoon Food Bank and Learning Centre and Let’s Talk Science, received a $500 EcoFriendly Sask Action Grant to combine youth education and outreach, waste reduction and urban agricultural research using vermicompost, vermicompost extract and commercial mycorrhizal inoculation.

The following information is based on a report prepared by Michelle Hubbard, with editorial assistance from Joanne Blythe and Brit McDonald.

1. To educate the community in general, and youth in particular, on vermicomposting and the potential of vermicompost and/or vermicompost extract in urban agriculture and gardening.

2. To make productive use of food waste generated by the Saskatoon Food Bank and Learning Centre through the production of vermicompost.

3. To evaluate the potential utility of commercially available mycorrhizae (Myke Pro) and vermicompost extract in sustainable urban agriculture in terms of plant performance and yield.

Six large and four small vermicomposting bins were started at the Saskatoon Food Bank and Learning Centre. Unfortunately, concerns about smell forced the number of bins to be reduced and restricted to Brit’s office.

Two grade 4/5 classes (Brunskill School and Nehiyawewin-Cree Language and Culture Program, Confederation Park Community School) toured the Food Bank and learned about vermicomposting. Each class took bins back with them to care for in their classrooms.

A field trial was conducted at the Garden Patch to assess the impact of vermicompost extract, mycorrhizae and both treatments together, to improve performance of a pumpkin, corn, and bean “three sisters” cropping system.

Healthy, intact soils are living systems containing a diverse array of microorganisms, including bacteria, mycorrhizal fungi, other fungi and invertebrate animals, such as worms. Soil organisms interact with each other and with plants contributing to soil and plant health. By adding mycorrhizae inoculant and compost extract, participants hoped to restore soil health and gain an increased understanding of the myriad of life right under our feet. Healthy soil is teaming with life, and regenerating soil benefits the environment.

Mycorrhizae are fungi which form symbiotic (mutually beneficial) relationships with the majority of land plants, including most vegetables and agricultural crops. Mycorrhizal fungi cannot complete their life cycle without compatible plants. These fungi colonize (grow within and out from) the roots of plants. The plants carry out photosynthesis, converting energy from sunlight to sugars. The sugars produced are shared with the fungi. In return, mycorrhizae provide numerous benefits to the plants such as increased root surface area, improved plant phosphorous nutrition, and drought tolerance. 

Compost extract is a liquid extracted from high-quality compost over a period of several hours. It contains the beneficial microbes (bacteria and fungi) from the compost. These microbes can enhance soil health, reduce the risk of plant disease, and promote plant growth. Extraction is done by submerging compost in highly aerated water. The resulting solution is strained to remove larger particles and is then diluted and applied to the surface of the soil.

In contrast, compost tea is made by growing a selection of microbes from high-quality compost in a sugar-rich solution under aerobic (highly aerated) conditions. Unlike compost extract, compost tea must be applied to soil within roughly two hours, before anaerobic growth begins.

Plant traits, such as leaf diameter and/or height and yield were recorded in order to measure the effectiveness of the different treatments. Neither mycorrhizal inoculation, application of vermicompost extract, nor both treatments in combination led to improvement in corn, bean or pumpkin growth or yield in terms of any of the traits measured as compared to the untreated control. Most plant parameters were unchanged by any of the treatments.

Various factors, including pre-existing soil quality and planting locations, may explain the results. Participants felt that they might have been able to increase the reliability of results if more volunteer hours had been available for measuring additional soil factors and taking repeated measurements.

The beans grew very large, likely suffocating the corn. Potentially, selecting alternative varieties, starting the corn from seed (to avoid transplanting stress) and/or planting the beans later could have ameliorated this problem.

Vermicompost outreach was done by Michelle Hubbard, Brit MacDonald, Maria Brown (LTS), Mark McLaughlin (PRI SK) and other LTS volunteers.

Bedding corn was grown by Janna Perry.

Field work was carried out by Michelle Hubbard, Janna Perry, Brit MacDonald, Joanne Blythe, Jim Wood and Concepcion Ponce with weeding by other Garden Patch volunteers.

The full report is available upon request.