Workers load vermicompost onto a truckbed at La Norteñita orchards.
La Norteñita has developed a composting operation to produce vermicompost for its 5,000 acres of orchards. Precomposted field lot manure is mixed with culled apples, other organic matter, and worms, and spread in windrows in layers of four inches at a time. The apples provide sugar to stimulate reproduction of the worms, employees explained.
The worms lay eggs in the mixture, which are incubated in the moist, warm environment. The temperature of the compost is between 20 to 25°C (68° to 77° F), and the moisture level is 82 percent. It can take up to 11 months for the compost to be ready to apply to the orchard, at which point the moisture level is reduced to 50 percent.
The vermicompost is applied at a rate of 10 to 20 kilos (22 to 44 pounds) per tree, or 5 tons per hectare, to bearing trees.
Benefits
The company perceives three types of benefits from the compost—physical, biological, and chemical. It physically breaks down clay in the soil and binds the sand particles, and the root zone stays moist longer so that irrigation is not needed so frequently.
Chemically, it supplies nutrients, such as nitrogen, phosphorus, potassium, and zinc, as well as humic and fulvic acid that help prevent diseases. And biologically, it provides microorganisms that make the nutrients more available to the tree.
IPM
La Norteñita uses integrated pest management practices and raises predator mites (Typhlodromus occidentalis) on bean plants in greenhouses for release in the orchards for mite control. Mating disruption is used for codling moth control, supplemented by the granulosis virus, with one trap per hectare for monitoring the pest.
Pesticides used include Success (spinosad), Esteem (pyriproxifen), and Intrepid (methoxyfenozide), and Thiodan (endosulfan) for the woolly apple aphid. The company has no organic orchards.
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