Almond Board of California is currently funding research on how best to recycle almond trees’ various coproducts – hulls, shells and woody material in an impactful way.
Through this research, California almond growers are learning about the potential of new ways to deal with tree material resulting from the removal of old orchards other than traditional cogeneration burning. While sending the woody material to cogeneration converts the wood to electricity, returning the wood back to the soil would return the nutrients and energy back to the soil ecosystem.
One concept getting closer attention is whole orchard recycling – grinding up entire almond orchards at the end of their mature life and incorporating the trees’ material into the soil, thus returning nutrients, improving the soil quality, and further sequestering the carbon contained in the wood chips.
An almond Life Cycle Assessment (LCA) study released last year by University of California, Davis showed that almond trees accumulate and store significant amounts of carbon during the average 25 year lifespan of an orchard. If the woody material is incorporated into the soil at the end of the orchard’s life, that carbon in the wood is only gradually released by soil microbes, extending the carbon sequestration. Thus, orchard recycling has the potential to contribute to reducing the carbon footprint of producing almonds.1
The potential benefits of the whole orchard recycling approach has led Almond Board of California to grant an expert team led by Dr. Brent Holtz, University of California (UC) Cooperative Extension, $145,000 to explore its feasibility.
With the grant, UC and USDA researchers will explore the following areas at multiple research sites in the Central Valley:
- Assess the costs, benefits, and overall management implications of recycling almond orchards back into the soil for almond production in California, including its ability to increase soil organic matter, fertility, water infiltration rates and water retention.
- Assess the costs and benefits of different methods of grinding up orchard woody material and incorporating into the soil.
- Expand initial Almond Board-funded research, which found that recycling tree material into the soil prior to replanting benefited the soil over time, to measure the impacts of adding woody material to the soil at new test sites.
- Determine whether whole orchard recycling could reduce net almond orchard greenhouse gas emissions by further sequestering the carbon stored by almond trees.
Whole orchard recycling includes grinding up entire almond orchards at the end of their mature life and incorporating the trees’ material into the soil, thus returning nutrients, improving the soil quality, and further sequestering the carbon contained in the wood chips.
Should this research provide evidence to support a change in almond farming practices, these recycling efforts could have major impacts on air quality, soil health and overall production efficiency, contributing to the greater sustainability of California almonds. Not only that, this approach seeks to mimic the ultimate sustainable system – Mother Nature – by following the lead of forests across the globe which are fueled by fallen logs and their decomposing woody material.
Whole orchard recycling is just one way Almond Board of California is committed to exploring the best use of all almond coproducts. Additional efforts are underway to find new, value-added approaches to use the hulls and shells of the almond fruit, as well as tree material.
1Kendall, A., Marvinney, E., Brodt, S. and Zhu, W. (2015), Life Cycle–based Assessment of Energy Use and Greenhouse Gas Emissions in Almond Production, Part I: Analytical Framework and Baseline Results. Journal of Industrial Ecology, 19: 1008–1018. doi: 10.1111/jiec.12332
