Study examines Pie Ranch poultry pasture

A red chicken coop at Pie Ranch in Pescadero is attached to an old artichoke trailer - sort of like a Winnebago for about 120 feathery travelers - so that it can be easily wheeled around the farm.

Every few days, Pie Ranch co-founder Nancy Vail moves the mobile coop to a different strip of fallow farmland for the chicken to use as pasture.

That gives the chickens plenty of ground to scratch, peck and use as a toilet. And that's a good thing, Vail said, because chicken manure is a strong fertilizer, giving the soil a boost of nutrients so it can later grow more produce.

Unlike other ways to fertilize soil, the benefits of having chickens pasture on fallow farmland has been based more on gut feeling than science.

Last week, Kathleen Hilimire, an environmental studies graduate student from the University of California, Santa Cruz, gave a short lecture at Pie Ranch to deliver her findings from the first study of chicken pasturing.

"It's been well-known that chicken manure is an effective plant fertilizer," Hilimire said. "Instead of the farmer applying manure, you have all these animals just running around applying it."

Researching the practice for her doctoral dissertation, Hilimire has been studying the soil quality and food-safety issues associated with chicken fertilizers.

Chicken compost, she notes, contains a tremendous amount of potassium, nitrogen, phosphorus and often calcium. Like any other manure, the droppings also can contain pathogens, so Hilimire strongly recommended the farmers wait about 120 days between applying manure and harvesting crops.

Her study led her to locate about 40 farmers in California who practice free-range chicken pasturing, including Pie Ranch. The Pescadero farm has been rotating chickens on and off different swaths of farmland since it first started in 2005.

During her study at Pie Ranch, Hilimire compared two farm sections growing strawberries, one that had been used for chicken pasturing and another that hadn't. Surprisingly, the chicken pasture didn't do as well, but Vail said that was really because they didn't know how to fine-tune the pasturing into their crop rotation.

"We're still trying to figure this out," she said. "It takes a long time to really get this down ... It's incredible now that there's firm research."