Reduction in Chemical Use at UC Botanical Garden

AKA Compost Tea Program at UC Botanical Garden

Project Leads: Chris Carmichal, Anthony Garza, Paul Licht

UC Botanical Garden LogoSponsor: UC Botanical Garden

TGIF Grant: $15,000

Project Theme: Habitat Restoration

Project Location

2010 Application Submission

Application Metrics

Status: Complete

Project Description: This project reduces chemical use in the UC Botanical Garden through a comprehensive Integrated Pest Management (IPM) Program that utilizes organic methods, including the production and use of compost tea in garden beds and on the lawn.

Goals: Establish a compost tea brewing and application system. Continue to investigate and use organic fertility regimes and pest control through the use of beneficial insects. Publicize the organic methods to campus and the general population through garden education programs. Provide a working model for the reduction of horticultural chemicals on campus and in the larger community. Reduce and ultimately eliminate most chemicals, particularly fungicides and synthetic fertilizers, and therefore prevent toxic runoff from entering the Strawberry Creek watershed. Host staff from Ganna Walska Lotusland Garden to train UC Botanical Garden staff on compost tea brewing. Contribute to the 2009 Campus Sustainability Plan's goal of "purchasing environmentally friendly products, minimizing use of toxic substances, and handling waste responsibly."

TGIF Blog Posts about UCBG

2011 Project Poster


TGIF Coordinator Katherine Walsh interviews Project Leader and UCBG's Supervisor of Horticulture & Grounds, Anthony Garza October 2010
(K) Where did you get the idea for a compost tea system?
(A) We have known about compost tea for several years and were interested, but certainly the biggest factors in pushing us along would be the working example at Lotusland Estate Garden in Montecito, CA, along with the funding provided by the TGIF Grant Program. We have slowly but gradually been moving to an Integrated Pest Management (IPM) System for quite awhile now, but more recently with disease problems and nutrient deficiencies in the garden, we have become more aware of our need for a more focused and intentional IPM System that incorporates organic principles, one being the compost tea system.

(K) Could you give a common description of how the compost tea system works?
(A) There are two primary functions of compost tea, but first a brief description of what this is: compost tea is essentially the aerated bag-brewing of a high quality thermal compost and/or vermicompost material. Additions to this mix may include humic acid, fish hydrolysate, and cold-processes sea kelp. A commercial brewer uses a suspended bag of this material that is aerated with a pump for 24 hours, and in our case, in a 100 gallon polyethylene tank. At the end of the "brewing", the resulting liquid is decanted into some type of spray system to be applied to plant foliage and/or to the soil. This "tea" is sprayed on foliage primarily as protections against foliar pathogens- in most cases, fungi. The additional ingredients mentioned (besides compost) are taken up somewhat by foliage, but can also be used as a soil drench to act as a more deliberate fertilizer and soil biology activator.

(K) Where will you use the system?
(A) We have some target collections that seem to have more disease incidence, and interestingly, more fertilizer requirements. At the moment, the two collections in this category that will receive tea applications are the Asian Collection and the Garden of Old Roses. However, we hope to use it in several other areas that need disease suppression, fertilization, or biological rejuvenation of the soil.

(K) What are some of the environmental benefits?
(A) One of the most apparent and immediate environmental benefits is the reduction or elimination of the use of synthetic materials such as fungicides and fertilizers onsite. Both of these materials can have adverse environmental impacts and also have the potentials to find their way into the watershed. Over time, with this system in place, the importation of heavy-input materials (ie. synthetic chemicals and fuel uses to deliver them) can be reduced or eliminated. Most importantly, by using compost tea and other organic materials, the soil health and biology can be restored and enhanced. With this comes a plethora of benefits including, but not limited to: the utilization by plants of organic nutrients, perhaps always present in the soil but not available without the correct soil biology in place; chemical balance and structural cohesion in the soils themselves thus allowing all types of beneficial soil organisms to flourish; improved soil, plant, and micro and macro animal health; and the improvement of water quality due to healthy soil's high quality nature as a biological filter.

(K) When can visitors see the compost tea system?
(A) Once the system is up and running (which TGIF will announce) 9am-5pm, seven days a week, except major holidays.

(K) Is there anything else our readers might find interesting?
(A) These systems are available in smaller sizes so that homeowners and others can actually take advantage of this type of bio-technology. With the smaller systems, depending on where they are used, one may have to buy the commercial compost instead of composting onsite. The quality of compost is of utmost importance to ensure a safe liquid end-product.

2010-2011 Accomplishments
UC Botanical Garden has been developing an Integrated Pest Management System over the last several years with the goal of switching UCBG to organic horticultural practices. From 2010-2011, UCBG made significant strides in reaching its goal by establishing a compost tea system.

  • In fall 2010, UCBG invited staff members from Ganna Walska Lotusland garden in Santa Barbara to visit and consult for UCBG on the compost tea system. The public workshop led by Lotusland was attended by the public, UCBG, Campus Grounds, and Blake Estate Gardens staff.
  • Garden staff and students in IB 112, Horticultural Methods, also received training in composting, vermi-composting, and tea production from staff at Liquid Biotech.
  • UCBG purchased a 100 gallon compost tea brewing unit, spray application equipment, and a vermi-compost unit. The vermi-compost unit was used to produce high-grade thermal compost (in itself, a new plus in for the garden) which then was brewed to create the compost tea.
  • As a result of the grant, UCBG did not purchase chemical fertilizers or fungicides during the spring growing season, and has moved toward an entirely organic fertility regimen.
  • From January through June, UCBG made 12 applications of compost tea in eight different collections in the Garden: Garden of Old Roses, Arid House, Southern Africa, New World Desert, Mexico/Central America, Australasia, Entry Plaza, and California.

2010-2011 Year End Report

UCBG continues to train students in IB 112, Horticultural Methods in compost tea production and application and organic plant health methods. UCBG will also continue to experiment with small tests of compost tea applications on other collections, such as the Garden of Old Roses, a traditionally chemically intensive area. UCBG received a 2011 CACS grant to hire a Compost Tea Intern and a 2012 TGIF Grant to hire a Green Garden Intern.

compost tea process

Mission Statement

The Green Initiative Fund (TGIF) provides funding for projects that reduce UC Berkeley's negative impact on the environment and make UC Berkeley more sustainable. TGIF will allocate funds to projects that promote sustainable modes of transportation, increase energy and water efficiency, restore habitat, promote environmental and food justice, and reduce the amount of waste created by UC Berkeley. Portions of the fund also support education and behavior change initiatives, student aid (via return to aid), and internships. TGIF is supported by student fees and administered through a student-majority committee and a program coordinator.