In 2010, Dirkse took part in the launch of ABC’s first sustainability education modules on irrigation and nutrient management. This self-assessment program also covers energy efficiency and air quality. It enables growers to compare their current farming practices with a set of best practices that make practical and economic sense in terms of sustainability, profitability and the environment.

Whether water, nutrients, fungicides, insecticides or other materials, La Mancha Orchards’ sustainability program is based on using a production input only when and in the amount needed.

“For example, we don’t apply a chemical or fertilizer just because it’s always been done,” Dirkse explains. “We have to have a good reason to use it. If it’s really needed to solve a specific problem, we’ll put it on. But, we don’t use any more than we have to. That saves money and it’s better for the environment.”


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Among his sustainable practices:

• Using water-conserving irrigation systems that apply water only around the tree. He uses a double-line drip system on one ranch, which features more rolling terrain, and micro jets on the other, where the ground is flatter.  Eliminating the use of water between tree rows also limits any weed growth, reducing the time and expense of chemical or mechanical weed control. To improve water use efficiency, Dirkse irrigates his orchards based on readings from soil moisture meters, which he’s installed at the rate of one every 50 acres, and ET rates.

• Shredding tree prunings instead of burning them. Doing this over a number of years has prevented the release of tons of carbon into the atmosphere and improved the soil by returning organic matter and nutrients to the ground, Dirkse reports.

• Growing an annual cover crop, such as native grasses, between the tree rows. Also, he’s trying to incorporate more bee forage, like mustard. This vegetation increases water absorption by the soil, while controlling erosion and dust. During the growing season he mows this vegetation as needed. Meanwhile, he uses a combination of pre-emergent and burn-down herbicides to keep the orchard floor under the trees clean to minimize debris at harvest when picking up and processing the nuts.

• Enhancing habitat in the orchard to attract insects, birds and other animals that feed on crop pests. A natural alternative to pesticides, these practices include providing nesting boxes for barn owls that help control gophers.