At a demonstration in Manteca, farm advisor and researcher Dr. Brent Holtz describes his research into the feasibility of chipping and incorporating entire almond orchards using five different pieces of equipment. A horizontal chipper in the background chipped the almond trees on site.
Five pieces of equipment rumbled through an old almond orchard in Manteca recently to demonstrate an alternative process for whole orchard recycling. An excavator uprooted trees, a front-end loader transported the trees to a horizontal chipper, and a spreader and rototiller then spread the chips on the ground and incorporated them into the soil.
The process of spreading and incorporating the chipped trees was demonstrated at a field day held at Tallerico Farms and conducted by San Joaquin County farm advisor Dr. Brent Holtz, who has been studying the feasibility of whole orchard recycling for eight years.
Equipment Comparison
According to Dr. Holtz, the five pieces of equipment could outperform the Iron Wolf, a single, giant machine that pulls, grinds and incorporates the trees in place. The Iron Wolf costs about $1,500 an acre to operate and recycles trees at the rate of 2 acres a day. The five different machines together cost about $1,000 per acre to operate and cover 15 to 20 acres a day. Moreover, the horizontal wood chipper grinds the trees more evenly into finer particles than the IronWolf, which left some sizeable chunks behind. This brings the whole orchard recycling option closer to economic feasibility for growers facing the process of replacing old orchards.
The chipping, spreading and rototiller equipment was operated by Randy Fondse of G&F Agricultural Service in Ripon.
Soil, Tree Effects
A modified spreader and a rototiller spread and incorporate chipped almond trees into a field where the trees once stood.In addition to researching a practical equipment option, Dr. Holtz’s work, funded by the Accelerated Innovation Management program of Almond Board of California, continues to look at the effects of incorporating the biomass of an entire orchard on soil characteristics as well as the growth and productivity of second-generation almond trees planted in the orchard.
According to Holtz, his research results suggest that the trees will do just as well or better in the presence of additional organic matter, which increases water infiltration and water holding capacity. In addition, as the woody material breaks down over time, it releases nutrients, including up to 1,500 pounds of potassium and 800 pounds of nitrogen per acre.
Observing the demonstration was almond grower Matt Visser, of Ripon. “When we took out an orchard 15 years ago and replanted it, I had an intuition that it would be good to incorporate that back into the soil, but that just wasn’t an option back then,” he said. “Whole orchard recycling meant you burned everything, or cut up the trees and sold them for firewood and burned the brush, or you chipped it all up and hauled it away for cogeneration plants.”
Favorable Option
With burning less of an option because of air quality concerns, and cogeneration plants shutting down, incorporating the whole orchard seems like a good direction to take, Visser said. “If you are getting a cumulative yield bump, at $2.50 a pound, and if you get 200 more pounds per acre to pay for incorporation, it sounds like it would pencil out.”
With the support of the Almond Board of California and a generous grant through USDA’s Specialty Crop Block Grant Program, Dr. Holtz and his colleagues will continue to evaluate the short- and long-term impact of whole orchard recycling on the health and growth of second-generation trees planted in the orchard, soil health, the orchard’s carbon footprint and nitrogen dynamics, as well as yield response to periods of reduced irrigation.
