Center for Regenerative Agriculture and Resilient Systems

Orchard Recycling Shows Great Promise for Climate Change Adaptation and Crop Security for California Almond Growers

by Sheryl Karas M.A., CRARS staff

almond orchard

In the Almond orchards around Chico and elsewhere in California, it has been a common practice to burn old trees that are no longer producing well in order to make room for new ones. But now one of the most important challenges facing agriculture is to increase sustainable food production in a changing climate while simultaneously reducing the greenhouse gas emissions that contribute to it. Some people have proposed that old trees be ground up or chipped and added to the topsoil prior to replanting in a process called whole-orchard recycling in order to stop adding to greenhouse gasses through burning. But it's hard for growers to choose to make this change without proof that it will be worth the time, money, and effort.

Interestingly, a number of factors have recently come together that may make whole-orchard recycling more attractive. High almond prices and the increased frequency of drought have encouraged orchard turnover more often in recent years. At the same time, new air quality regulations in California and the high cost of burning permits makes this expensive. Some farmers have been sending their trees to biomass power generation plants to be recycled to avoid these costs, but since 2015 falling gas prices have forced closures of many of these plants. That means many growers are searching for alternatives, and the just published results of a study led by the University of California on whole-orchard recycling (WOR) has come just on time. The study shows that not only could WOR be a great solution for addressing climate change but also, eventually, for the grower’s bottom line.

Researchers compared the soil health and productivity of an almond orchard using WOR versus burning their old orchard biomass nine years after implementation. They also conducted tests to monitor shifts in tree water status and resilience. They found that WOR led to higher crop yields (about 15% higher) and substantial improvement in soil functioning, including nutrient content, aggregation, porosity, and water retention. The practice sequestered significantly higher levels of carbon in the soil, increased irrigation water efficiency by 20%, and improved soil and tree water status under stress. While there were some added costs created by using this method in the short-term, researchers concluded that the higher yields and other benefits offered a promising strategy for long term improvement in soil health and reduced risk of crop failure due to climate-related stress. There is also the potential for offsetting costs or even increasing profits through grants for carbon-farming(opens in new window) and carbon farm credits(opens in new window).

 The amount of carbon sequestered in the soil in this study amounted to approximately 2 metric tons per acre. Because California currently grows about 1,530,000 acres of almonds (PDF), that represents an enormous potential for carbon sequestration with just this one crop alone if all growers were to adopt this method (3,060,000 metric tons per year). The Almond Board of California(opens in new window) estimates that  thirty to forty thousand acres of old almond orchards will need to be removed each year over the next decade.

Researchers were enthusiastic about the multiple benefits provided by whole-orchard recycling in their study. They further reported that interdisciplinary evaluation regarding pest and disease potential and overall C footprint showed no major drawbacks. They concluded that WOR should be considered a climate smart practice for California irrigated almond systems. Read the full report here.(opens in new window)