Reduction in Chemical Use at the UNIVERSITY OF CALIFORNIA BOTANICAL GARDEN{compost tea program} Anthony Garza, Supervisor of Horticultue and Grounds, UCBG Chris Carmichael, Associate Director of Collections and Horticulture, UCBG
Tea brewer
Tea brewer aeration in process.
Thermal compost pile.
Commercial vermi-compost bin.
Background
The UC Botanical Garden (UCBG) occupies a 34 acre site in Strawberry Canyon and houses one of the country’s most extensive plant collections. Over the past several years UCBG staff has been working to formulate a comprehensive Integrated Pest Management (IPM) Program including a switch to organic horticultural practices. Chemical use at the UCBG has always been low relative to standard agricultural and lawn maintenance practices, in part due to the diversity of its collections. We have always believed that the UCBG’s location in the Strawberry Creek watershed places a focused responsibility on scrupulous chemical management within the Canyon.
Theory
The goal of this project was to reduce chemical use in the UCBG through the introduction of an Integrated Pest Management (IPM) Program utilizing organic methods that have proven highly successful at other botanical gardens in California. The focus of this project is to establish a compost tea brewing and application program. The use of a compost tea system builds soil health, acts as fertilizer and provides beneficial microorganisms that suppress or eliminate pathogenic fungal problems.
Process
The first phase of our project involved training in organic fertility regimens in general and the use of compost tea in particular. To ensure best practice methodology we invited a staff member from Ganna Walska Lotusland garden in Santa Barbara to visit and consult. Lotusland has been a pioneer in compost tea application and reports excellent results. During the visit we hosted a public workshop for the campus community, attended by UCBG staff and students, as well as staff from Campus Grounds and the Blake Estate Gardens. The second phase of the project involved the production and application of compost tea. We purchased a 100 gallon compost tea brewing unit and the associated spray application equipment. To produce the tea we obtained a vermi-compost unit (aka worm farm or bin) and began producing our own high-grade thermal compost. Products from these two sources, as well as purchased organic nutrients have been used in compost tea production and application. Garden staff and students in IB 112 (Horticultural Methods) received training in composting, vermi-composting, and tea production from staff at Liquid Biotech out of Watsonville, CA.
Outcome
The program is fully up and running and we are applying compost tea, including specialty brews targeted at certain pathogenic fungi and as fertilizer for particular plants. As a result of this program we have purchased no chemical fertilizers and fungicides this growing season, and have moved significantly closer toward implementing entirly organic pest management and fertilization regimen.
Staff and student compost training.
Worms in action.
Electric sprayer unit with tea tanks.
Final application in the field.