April 22, 2010 | General

Compost, Mulch Connection To San Diego County Agriculture

BioCycle April 2010, Vol. 51, No. 4, p. 24
Factors such as drought, irrigation water restrictions, real estate development, and new rules on runoff are elevating use of locally produced compost and mulches on county farms.
Rich Flammer

SAN Diego County, California has a Mediterranean-like climate ideal for a multitude of crops and livestock. In addition to four distinct microclimates dividing its 4,225 square mile land mass, a wide range of soils and vegetation regions exist. These include, among others, desert, chaparral, woodland, grassland, riparian, montane, marsh, estuary and coastal dune. The region’s variations in weather, geology and biology allow diversity in agriculture and ranching. Over 6,000 farmers occupy 30 different vegetation communities (micro variations in both climate and topography) and produce more than 200 commodities.
What makes San Diego County truly unique is the fact that 92 percent of the farms are family owned, 77 percent of the farmers live on their land, and the median farm size is five acres. In addition to being home to more small family farms than any other county in the U.S. (6,565 – San Diego County Farm Bureau), San Diego leads the nation in number of organic farms (343 – County of San Diego Department of Agriculture, Weights and Measures), and is second in the country in farms with a woman as principal operator. This community of family farmers, many of whom are currently practicing or beginning to convert to sustainable methods, ranks 12th in the U.S. in agricultural commodity output for counties (compared to more than 3,000 surveyed nationwide), bringing $5.1 billion of annual value to the regional economy, and greatly contributing to California’s ability to produce approximately 25 percent of the United States’ table food and 12.8 percent of the nation’s total value of agricultural production.
Nationwide, San Diego County ranks #1 in the production of nursery crops and avocados, #2 in acres of guavas, pomegranates, limes, and macadamias, #3 in honey production and #5 in lemons. There’s little debate that this is an enormously important growing region. Its preservation is both practical to ensure the security of a healthy local food supply and symbolic in terms of fostering the continued existence and rekindling of the family farm, sustainable agriculture and sound resource management. So why is its future so threatened, and what forces are working towards its failure?


Despite the abundance of small farms, San Diego County is less rural than the numbers may indicate. In fact, it is so well developed, more than 2.6 million people reside here, making it the sixth highest urban population among counties in the United States. “There used to be clear divisions between the urban and agricultural areas,” observes Eric Larson, Executive Director of the San Diego County Farm Bureau (SDCFB). “It’s very difficult to tell the difference now.” Development, largely housing tracts of hundreds or thousands of cookie cutter homes and strip malls quickly following suit, has pushed agriculture from fertile coastal regions to inland valleys, and even high up onto slopes. Drive through San Diego County’s scenic Pauma Valley, for example, and avocado orchards can be seen creeping up steep hillsides like a green glacier moving in reverse.
Poor planning and lack of adequate infrastructure has led to loss of millions of acres of indigenous species, open space and contamination of local ground and surface waters, including coastal bays and the Pacific Ocean. And of course, prime farmland is being lost too. Since the mid 1980s, more than 2,500 farms and over 6.2 million acres of agricultural land have been taken in California, and the trend is continuing in San Diego County as development pushes east.
While the battle for suitable land continues, it pales when compared to the fight farmers are facing from a direct consequence of poorly planned overdevelopment. Water. Not only does market demand and expense related to conveying water hundreds of miles translate to its high costs (currently more than $600/acre foot), but even a farmer who can afford the water and land required to produce commodities with the highest dollar value per acre can’t be assured access to all that’s required to adequately irrigate crops.
The combination of high land and water costs in the region pushes farmers into a financial survival mode, many of whom are squeezed into producing whatever yields the greatest potential revenue. This dynamic leads to food crops being replaced by ornamentals, further separating southern Californians (and many Americans too) from their food supply. Exacerbating the issue are an aging population of farmers, whose children and grandchildren opt to sell family land rather than inherit the increasing challenges of farming it, and shortsighted land use regulations that often favor speculative development over preservation of local agriculture.


By far, the cost and availability of water is the single biggest issue facing San Diego County farmers, and indeed, all California growers as well. At one time, water was both cheap and plentiful. Farmers could grow practically anything anywhere in the county, including the desert areas, and still make a profit. But due to severe dry cycles locally, in southern California as well as in the Colorado River Basin, and regulatory restrictions 600 miles away in the Sacramento-San Joaquin River Delta, irrigation water for farmers has been cut. As the majority of San Diego County’s water supply comes from the Colorado River and Sacramento-San Joaquin Delta, these sources are critical to agriculture.
In early 2009, key reservoirs were down to as little as 35 percent of capacity, prompting California Governor Arnold Schwarzenegger to proclaim a statewide drought emergency and seek federal assistance. But quantity of water is just one of the challenges. Getting it from its source to market is another critical issue. California’s water conveyance system was completed in the 1970s, and hasn’t been expanded since, despite a state population that has nearly doubled from just below 20 million then to 38 million in 2009.
As a result of these irrigation hurdles, and spiked by a slumping economy, hundreds of growers statewide have been forced to let hundreds of thousands of acres lie fallow. Others have been able to hang on, but face yet another obstacle related to a water challenge from the opposite end of the field. The Federal Clean Water Act and the California Porter-Cologne Act make it illegal for any irrigation or storm water to carry pollutants off the farm site. Best Management Practices (BMPs) must be implemented to comply, and runoff testing will become mandatory for all county farms. This is already taking place in a number of areas statewide, but will go into effect in 2011 in San Diego County.
To promote the use of curbside-generated yard trimmings, the California Integrated Waste Management Board (now CalRecycle) funded 13 demonstration projects between 1994 and 2002 that focused on agricultural or soil erosion issues. The studies revealed positive results, and compost and mulch-based BMPs for erosion control, storm water management, and watershed protection have since been recognized by CalRecycle as well as the US EPA, University of California Division of Agriculture and Natural Resources, California Department of Transportation (Caltrans), and County of San Diego Watershed Protection Program, among others.
All owners of agricultural operations – both large and small – will be required to either file a Notice of Intent directly with the Regional Water Quality Control Board (RWQCB) by January 1, 2011, or enroll in a monitoring group by December 31, 2010. Operators who don’t want to report directly to the RWQCB have the option of enrolling in the SDCFB’s San Diego Regional Irrigated Lands Group (SDRILG). The enrollment fee is $200/acre (capped at $1,000). This option is cost-effective for farmers, and simplifies reporting.
The SDCFB Board of Directors recently decided to incorporate the SDRILG as a 501(c)(3) nonprofit corporation as not all members will be participating in the group and the work is primarily educational. Once water quality data is gathered, farmers will be educated on ways to reduce the pollutants detected. After the enrollment period has closed, the SDRILG will begin collecting more detailed information about the participating farms, and hire an engineering firm to provide the technical assistance needed to comply with the water monitoring regulations. This program will facilitate compliance for farmers, who must meet the broad regulatory requirement to “implement management measures or best management practices to minimize or eliminate the discharge of pollutants.”


When polling San Diego County farmers about use of compost and mulch, Larson found growers not already using these products had an increased interest in their potential to reduce irrigation requirements as well as comply with runoff rules. Both of these water issues are relatively new to the San Diego County farm community, as are using compost and mulch. Local farmers expressed both optimism and concern with regard to incorporating them into their regime. Many wanted to use fewer chemicals for disease and weed control, listing increasing fertilizer and pesticide costs, health risks associated with working with these products, runoff regulations and pesticide drift as reasons. Other farmers remain uneducated about these products’ potential, and expressed concerns that include difficulty applying mulch on steep slopes and increased overhead costs related to transportation and application.
The Farm Bureau and local composting community are working to educate these growers, and are focusing on the following advantages of mulching, using compost to amend soil, or composting on farm:
• Diversification of a farm’s revenue stream from composting as a means to offset profit margin losses due to increasing land and water costs. A local 100-acre dairy farm has chosen this route and is composting its manure as well as collecting tipping fees for yard trimmings.
• Utilization of composted soil amendment to increase the water holding capacity of soil.
• Mulching to reduce soil surface heat and excessive evaporation (local farmers interviewed agreed it helps them keep a stable water content in the soil) and soil surface moisture loss (with savings of 20 percent and greater reported).
• Mulching to aid retention of rainwater. When San Diego does get rain, a paltry 9-inch average annually, farmers desperately need to keep it.
• Amending soil with compost and mulching to mitigate runoff. The Farm Bureau promotes the University of California Cooperative Extension’s compost and mulch best management practices to members for this purpose.
• Prevention of soil erosion. This is particularly important to comply with runoff rules and help farmers maintain topsoil when growing on hilly landscapes prominent in San Diego County.
• Disease and weed control. A 1997 University of California study completed on mulches in citrus and avocado plantings found a dramatic reduction in the number and variety of weeds, particularly broadleafs. In addition to a substantial labor savings for the farmer, weeds no longer competed for moisture with crops, and inoculant potential from Phytophthora cinnamomi – a soil-borne pathogen that infects woody plants causing root rot and cankering in avocadoes and citrus – was substantially reduced. A number of citrus growers in the county use mulch for this reason.


As challenges increase for San Diego County farms, the SDCFB has ramped up its efforts to lobby for more balanced land use and water regulations, preserving county agriculture, and promoting more economically and environmentally sustainable farming, including use of composts and mulches to meet the expanding challenges of regional land and water issues. The SDCFB promotes three Business Supporting members of its organization that provide organics to farmers, and is working on an attempt to get the county to ease restrictions on on-farm composting.
Farm Bureau representatives meet regularly with the Regional Water Quality Control Board to develop runoff testing protocols for agriculture, give input to the County Water Authority on an agriculture water pricing project currently in process, and will soon be assisting the American Farmland Trust to develop a Purchase of Agricultural Conservation Easements program for the county. The SDCFB is also helping local farmers by opening certified farmers markets.
While the issues local farmers are facing may be too complex for organics alone to solve, certainly composting, mulching and local production and consumption of foods weigh in as enormous factors in the fight to save San Diego County’s agricultural community, food supply and environment. Success here will undoubtedly serve as a model for other growing regions, as sustaining the county’s rich agricultural heritage will require a combination of the most economically and environmentally sensible approaches to organic resource management and farming. With proactive efforts already underway by the Farm Bureau and the local agricultural and resource management communities, there remains a strong potential for success.

Rich Flammer of Hidden Resources, Inc. ( is a Contributing Editor to BioCycle.
Sidebar p. 26

SAN Diego County growers interested in reducing irrigation demands and practicing more sustainable farming methods can learn firsthand from the Tierra Miguel Foundation, an 85-acre working organic produce farm located about 50 miles northeast of downtown San Diego in the Pauma Valley. Founded in 1999, Tierra Miguel is a 501(c)(3) charitable organization offering a multitude of educational programs and demonstrations of the value of local, sustainable agricultural practices.
Tierra Miguel not only works with farmers, but with conservation groups, government agencies, schools, children, adults and anyone interested in or who can benefit from sustainable food production. Tierra Miguel’s many offerings include the Farm to School Program, San Diego Grower’s Project, School “Edible Garden” Program and a Biodynamic Farming Course and Community Supported Agriculture (CSA).
In 2003, recognizing that the foundation of sustainable farming is ensuring lands to cultivate are preserved for agriculture, Tierra Miguel was able to secure Historic Federal and State of California grants totaling $1.91 million “to preserve in perpetuity the agricultural productive capacity and open space character of the property.” Most of the grant monies came from a fee title grant, however, and had to be returned to the agencies at the close of escrow. Then in 2007, the Pauma Band of Mission Indians purchased the land and provided Tierra Miguel a long-term lease and donated $350,000 to the farm as well as an educational/working grant in the sum of $300,000 over ten years.
Two of the farm’s most important programs to preserve and enhance San Diego County agriculture are its Green Waste Composting Demonstration and Soil Conservation Program. While Tierra Miguel has been composting since its inception, the demonstration project was designed as a training tool and model for other San Diego County growers to follow. “We provide ongoing training for farmers wanting to compost,” says Milijan Krecu, farm manager. The farm has both scheduled workshops and ad-hoc training. “If a farmer calls and wants to learn about composting, I’ll invite them over,” adds Krecu. Tierra Miguel has an open house on the first Saturday of each month, when most of the smaller growers visit to learn the myriad sustainable methods, including composting, which the farm practices in its own production.
Tierra Miguel composts straw and manure from a local dairy, yard trimmings from landscapers, and residuals and spoilage from its own crops and produce in open windrows. Finished compost is used by Krecu and his staff to teach and demonstrate utilizing compost-amended soil and organic mulches for disease and moisture management, transitioning to becoming an organic farm, and diversifying revenue streams and developing alternative marketing strategies through compost and mulch production and sales.
Tierra Miguel collaborates with San Diego County and the USDA-NRCS to educate local farmers on the benefits of compost and mulch for erosion control, reduced water use, disease and insect control and improved soil fertility. It’s also working with University of California Cooperative Extension on a research program investigating the benefits of mulch as a means to increase water savings and crop yields in avocado orchards, studying the effects of mulch on irrigation design, moisture retention and evaporative loss.

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