The Central Valley of California produces 80% of the world’s almonds, achieving higher yields than any other growing region. However, this success comes at a cost: like many other Central Valley crop fields, almond orchards have low biodiversity, high pesticide and fertilizer use, leaching and salinity issues, substantial water demands, and problematic air emissions. Since 2009, the Almond Board of California has implemented a sustainability program to encourage growers to reduce their impacts. In this context, individual almond growers must make complex and sometimes difficult tradeoffs between long-term sustainability and short-term viability.
Over the past decade, researchers have developed a new tool for sustainable soil and biomass management in almond orchards: whole-orchard recycling (chipping the old trees and returning the wood chips directly to the soil, instead of burning the trees in the field or sending the chips to a biomass power plant). The ecological and agronomic efficacy of whole-orchard recycling has been demonstrated in field trials; however, grower adoption rates are still in the low single digits. We conducted a series of surveys, interviews, and field visits to understand the tradeoffs that growers consider when choosing whether to adopt this practice.
Results/Conclusions
We surveyed 181 growers, crop advisors, and other almond professionals about their perceptions of whole-orchard recycling (WOR). WOR has been shown to increase soil carbon, microaggregates, infiltration rate, microbial activity, and water-use efficiency while eliminating the need to burn woody biomass. Our survey respondents were aware of these benefits, but most (78.5%) had not tried the practice. They cited two primary obstacles: cost (WOR costs an additional $125-$810/acre) and concerns about disease transmission from old wood. Other concerns included difficulty with orchard floor management and nitrogen immobilization due to high carbon input.
Our 30 follow-up interviews showed that growers who had actually done WOR found these problems manageable – especially with financial incentives to offset the cost. However, the question of disease remains an obstacle for which there is little data to allay the concerns of skeptical growers. Theory suggests minimal risk, but growers are hesitant to start a 25-year investment in a new orchard with possible disease problems. Growers also want to see long-term analyses that demonstrate economic advantages of WOR (and complimentary practices, such as cover cropping and fallowing between orchard plantings). Applying research effort to these practical questions can enhance almond growers’ confidence in meeting their sustainability goals.