Looking back, you could see it coming when the California Air Resources Board took action --- in January 2004— and banned the burning of residential waste. Now the clock moves forward to a deadline for doing the same to agricultural waste burning, defined as “the intentional use of fire for vegetation management in areas such as agricultural fields and orchards…removing orchard trees and vineyard prunings.”

Limited in the San Joaquin Valley since 2003 with burning now allowed by permit and only on Permissive Burn Days, the deadline is approaching when even that option will disappear and ag burning in the Valley will be prohibited by January 2025.

“The San Joaquin Valley Air Pollution Control District has reduced agricultural burning with 2025 being a key target date to meet federal clean air standards,” according to CARB Chair Liane Randolph.

Brent Holtz, who pioneered the concept of whole orchard recycling, thinks it’s about time his concept was implemented. “We’re in a good position with the tree nut industry relative to alternatives to open field burning, especially so since incentives of some $600 per acre were offered to growers to consider whole orchard recycling versus burning. That incentivized a lot of growers to try WOR,” said Holtz, UCCE farm advisor, who has been grinding up and recycling old trees long before he earned a plant pathology doctoral degree from UC Berkeley. “Plus, I’ve heard those incentives are going to increase and that prompts more interest.

“For the last hundred years or so our agricultural practices have generally depleted the soil, taken its organic matter out of the ground, so anything that can be done to bring that back is good practice. We’re now putting organic matter back into the land, building up soil carbon, and in the process, increasing water-holding capacity and soil fertility.”

According to statistics from the San Joaquin Air Pollution Control District, over the last five years, more than 500 growers have begun using whole orchard recycling in the Valley and have to-date recycled more than 26,000 acres, diverting some 750,000 tons of wood from being burned.

‘A pretty good situation’

That’s good, and getting better, said Holtz. “Among tree nut growers, especially almond and walnut growers, we’re in a pretty good situation because we’ve been shredding prunings and recycling for years. There are some hold-outs though in the vineyards where they have a lot of wire trellising and metal stakes and are least likely to recycle because it’s easier to push the vines and wire into a big pile and burn it off.”

Acknowledging that “almonds are the gorilla in the living room” because there are 1 ½ million acres of almond orchards and on any given year about 10-15% are pulled out and need to be disposed of, Holtz said: “Most of our acreage is in younger trees, but there’s probably about 500,000 acres of older almond orchards that are 20 years or older. And ten percent of that figure represents some 50,000 acres of removed trees that need to get burned or recycled.”

Admitting a bias in favor of whole orchard recycling over other technologies such as air curtain burners, he summarizes: “I can’t think of a lot of reasons for people not to recycle their orchards as our trial research has shown a resultant increase in yield with new research showing increased water-holding capacity and higher soil fertility. And if growers who are environmentalists can ultimately get some sort of carbon credit for putting carbon back into the ground, that might promote an even bigger win-win situation.”