Orchard recycling improves climate change adaptation and mitigation potential of almond production systems

increase tree endurance and yield resiliency potential in response to water shortages. These increases in yields coupled with reduced water stress make it an advantageous practice in semi-arid climates such as the Central Valley of California, where deficit irrigation is common pre-harvest and water scarcity is an increasingly serious challenge for growers. Conclusion Despite added complexities and costs, we show that in situ biomass recycling holds great potential to sequester C in soils while improving yields and other ecosystem services that con- tribute to productivity and input use efficiency. Potential improvements in soil quality further highlight the beneficial implications of WOR for orchard adaptation to future climate varia- tion and the potential of healthy soils to build resilience to irrigation supply shortages in almond orchards. The broad ecosystem services offered by orchard recycling make it a valu- able alternative over the conventional methodology of in-field whole tree burning or hauling the tree biomass to the co-generation plants in California and elsewhere. Interdisciplinary evaluation of this practice regarding pest and disease potential and overall C footprint has shown no other major limitations [6], and overall C footprint assessments and best manage- ment practices are under development to realize the potential of this practice in a dynamic agricultural landscape. Supporting information S1 Fig. Almond kernel yield from 2014 to 2017 (a) as well as the cumulative kernel yields (b) at the Kearney site. Bars are standard error. (TIF)

S1 File. Spreadsheet data. (XLSX) S1 Table. Accumulation of mineral nutrients in the almond leaves as influenced by the irri- gation and soil treatments. (DOCX) S2 Table. Photosynthetically Active Radiation (PAR), as well as yield per unit PAR inter- cepted, and canopy temperature in different soil and irrigation treatments. (DOCX) Acknowledgments We thank Dr. Bruce Lampinen and Mr. Samuel Metcalf for PAR measurements in this trial. We also thank the University of California’s Informatics and GIS Statewide Program for aerial thermal imaging of the orchard and data processing. This study would have been impossible without the cooperation of Chuck Boldwyn and Dale Pattigan and the contributions of the University of California Kearney Research and Extension Center. We appreciate the Burchell Nursery for providing the almond varieties at their cost for planting. This project was funded by the Specialty Crop Block Grant Program of the California Department of Food and Agricul- ture and the Almond Board of California. Author Contributions Conceptualization: Brent A. Holtz, Ame´lie C. M. Gaudin. Data curation: Emad Jahanzad, Cameron A. Zuber, Sean Hogan. PLOS ONE Whole orchard recycling PLOS ONE | https://doi.org/10.1371/journal.pone.0229588 March 27, 2020 18 / 22