Composting goes scientific to get the best blend for specific
crops
By Jen Penkethman Special to the Dispatch
Gilroy – From high on a hill just off Pacheco Pass Highway in Gilroy, a new product, made from discarded food and organic waste of Gilroy’s citizens, churns in a big tumbler. One man’s dirt is another man’s gold, and according to Robert Reed, growers will be clamoring for this new, phosphate-enhanced compost.
“The new blending process has growers very excited,” said Reed, a spokesman for South Valley Organics, which operates just outside of Gilroy.
The blend includes rock phosphate, an essential element for fertile soil. Think of the little white rocks that come with your household potted plant – this is rock phosphate, but undigested, and unusable for plants in pebble form. South Valley Organics, with the help of Bob Shaffer, an agronomist (soil expert), have developed a new method which blends the phosphate into the soil so that plants can sip the nutrients directly through the root.
“A lot of places on hillsides in northern California are deficient in phosphate,” said Shaffer. “For some farms, this compost is really crucial.”
The phosphate used comes from a mine in Florida, but the base – the black soot-like dirt that makes up the bulk of the compost – could come from your own kitchen trash bin. South Valley Organics receives 200 tons of organic waste every day, and has to refine all the tree clippings and pizza boxes into a product that will help plants grow.
At the site on Hecker Pass Highway just outside Gilroy – which has the general smell of vegetables left in the fridge too long – huge mounds of rich dirt are tumbled and churned, watered, and aerated. Inside the mounds of dirt, microscopic organisms digest the various elements into a fine black powder, and in the process generate temperatures that can top 131 degrees.
The product that results is called Four Course Compost, and it can be used by anyone from professional farmers, to landscape companies, to a backyard gardener. Interested customers can order the compost from Home Depot or Orchard Supply in Gilroy, in a process that is essentially circular and sustainable.
“It’s a closed circuit,” said Timothy Daleiden, who oversees operations at the Gilroy facility. “People dump the food or organic material into the trash, the trash gets taken out here, we process it, and they can buy it back to grow plants.”
South Valley Organics, which is part of South Valley Disposal & Recycling, sprang into being after legislation was passed in the early 1990s which mandated that waste could no longer be dumped entirely in landfills. Part of the hill in Gilroy used to sort compost is a landfill, and tires still dot the landscape, but Daleiden says the facility is not accepting any more general waste – it’s all “green waste” now.
Although compost has been available for several years, the refinements it’s going through now – adding phosphate, calcium carbonate, gypsum’ and other nutrients – is a major change, because now a grower can match the needs of the farm to the product.
Sarah’s Vineyard, on Hecker Pass, bought and uses the Four Course Compost because, as proprietor Tim Slater said, “They were able to give us an analysis of the critical minerals we needed, and it was easy to know what to buy.”
NorCal Waste Systems, located in San Francisco, is the largest employee-owned company in the solid waste industry. The waste company works with a number of sites, including the one on Pacheco Pass, to blend the right kind of compost for each grower. The Gilroy facility processes 20,000 tons of organic waste every year, of which about 15,000 can be seen towering atop the hillside at any given time.
Gilroy is one of the major vendors of this product, which is also made at facilities near Vacaville and north of Sacramento. This time of year, the window between summer and the winter rains, is the best season for growing and selling compost. Daleiden said he already anticipates a boom in the business in the years to come.
