As some of you know, Frog Hollow will be planting 18 acres of almond trees in 2018! Even though we are skilled at growing other stone fruits (yes, almond is a stone fruit), almonds will require some new techniques, including tree shaking for harvest and post-harvest removal of hulls and shells. Needless to say, we are studying up!
Contrary to popular belief, almonds are not botanically categorized as nuts but as “drupes,” or stone fruits. Nuts are fruits made up of an inedible hard shell and an edible seed (chestnuts, hazelnuts), while drupes have an outer fleshy part surrounding a shell (also called the “stone” or “pit”), with a seed inside. Some obvious drupes are peaches, cherries and plums. However, almonds, walnuts and pecans are also drupes… but instead of eating the outer fleshy parts of these last three, we eat the seeds inside the pits! In the case of almonds, we call the outer fuzzy layer the “hull” and the casing around the almond kernel itself the “shell.” Therefore, after harvest, a grower must go through 2 extra processes, hulling and shelling, in order to reach the edible almond.
To kickstart our self-education about almond growing, I attended the Almond Conference in Sacramento. At the conference, I found learning about almond co-products (hulls and shells) fascinating. Not only can the hulls and shells be used for livestock bedding, feed, biochar and compost substrate, but scientists are looking into many other applications as well. At UC Davis, researchers are developing a “bio solarization” process with almond hulls. This technique uses solar and microbial processes to control soil pests on farms. In an area of high nematode pest pressure, the research suggests that incorporating almond hulls into the soil and covering the area with a tarp can produce a soil environment where anaerobic chemical activity promotes the accumulation of acids toxic to the targeted pest! Wouldn’t it be great to make use of these almond “waste products,” diverting them from landfills and using them as bio-pesticides, thereby avoiding applying harsh chemicals to the soil? Beyond on-farm applications of almond biomass, USDA engineers are also working on incorporating almond shells into biodegradable plastics, creating flower pots, garbage bags and even tires. I am excited to brainstorm how we will use our almond shells and hulls at Frog Hollow!
Author: Rachel Sullivan
Rachel Sullivan is the Farming Assistant, with a focus on soil science, at Frog Hollow Farm. She grew up working in her parents’ bread bakery in Berkeley and went on to study Sustainable Agriculture and Business at Cornell University. Post graduation, she worked at TomKat Ranch Educational Foundation, where she analyzed the carbon sequestration potential and microbial community composition of regeneratively managed rangeland soils. She is excited to help Farmer Al and the teams at Frog Hollow with all sorts of projects- from fertilization planning to wheat product development to soil sampling!