Once upon a time, it wasn’t hard to get rid of almond hulls and shells, according to UC advisor Dani Lightle.
“It wasn’t really a pressing need. There was a home for some of this stuff. Hullers could make a small amount of money that they could pass on to the growers, or it could cover the cost of getting rid of everything,” she said.
Lightle said that now hullers are in a position where they may need to charge growers to get rid of hulls and shells--thus her new research along with UC colleagues to find new uses for hulls and shells.
“There’s a fair amount of research going on into future uses of hull and shell,” Lightle told growers, presenting her research at a recent conference. “Something we can do right now that’s fairly straightforward is put it back out in the orchard and recycle it back down that way.”
Her team tried the experiment at three sites in Butte and Merced counties.“By the time we got to harvest, there was basically nothing (uncomposted) left. There were no harvest issues,” Lightle told growers.
The team’s research was meant to find out whether traditional beliefs are correct that reapplying hulls and shells could be harmful to trees.
So far, there’s scant evidence that shows harm.
There were no differences in kernel sizes during harvest after incorporating hulls and shells, and while there were some yield differences at the Butte location, those coincided with separate issues of bacteria blast and brown rot.The results of the work are that negative impacts appear unlikely, and long-term application of reincorporated hulls and shells may have a bigger benefit for soil health and nutrient uptake.
One other big question is about the costs of trucking hulls and shells, Lightle said.
If a huller/sheller has trucks going to and from the field, it’s possible the trip could be “free” because it would replace a truck returning to the orchard empty.
In that case, there could be a significant total benefit, if the hulls and shells also displace organic matter with food safety risks.
“The economics are not really well played out at this point, but consistently that’s what I hear, the trucking costs, the trucking costs,” Lightle said. “Transportation is going to be a big factor into whether or how this is adopted.”
