Whole Orchard Recycling Could Improve Soil Fertility
New Technology Isn’t Cheap
No grower has actually purchased a Slasher yet, no doubt because of the relative newness of the technology and its expense. The one demonstrated in Chowchilla is the newest model, the IronWolf Slasher 700B. Purchased new it costs about $1.3 million, says Howe.
However, if growers already have a heavy-duty bulldozer, they can mount the Slasher unit. Sold separately, the IronWolf Slasher costs between $450,000 and $500,000.
Holtz estimates running the Slasher could cost about $1,500 per acre, compared to about $1,000 per acre for a tub grinder. Holtz notes that if someone were to purchase the Slasher and provide a service to growers, the expense would be lowered some.
Tree size is another factor to consider. The Slasher grinds trees in place, which, as mentioned, concentrates the spread of the chips into a 10-foot strip. That means when grinding larger trees, such as the 25- to 35-year-old almond trees in the Chowchilla trial, a large amount of biomass will be left in one place.
Such large trees, which Howe estimated had an average diameter of about 27 inches, take a fair amount of time to chew up. He said he could do about two acres a day. He could double the speed, tackling four acres a day, if the trees were more like 22 inches.
Howe says he’s encouraged by Holtz’s results, which show the Slasher is the only unit that can go down below the surface of the soil and take care of tree roots. Without the availability of cogeneration facilities, growers who used to get paid so much per pound for wood pulp are going to have to essentially pay so much per pound.
Holtz says his 2008 trial established some excellent groundwork, but the current trials, once complete, should provide even more insight.
“We’re forming a research team to look at this all in depth,” Holtz says.
Howe is confident the Slasher will be the best option for growers who are interested in replanting older orchards with newer varieties on far more high-yielding production systems.
“Bigger growers are looking into the future and they’re getting ahead of it,” he says. “They know they have to replace their trees, and there’s going to be a change in the way people manage crops based on when [orchards should be replanted].” ●