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

macroaggregates and physically protected intra-aggregate SOC [51,52]. However, without any sustained C inputs, the C benefits of this practice might decrease over time, especially if smaller fast degrading woodchips are incorporated. Given the potential of this practice for C seques- tration, holistic assessments of C turnover and the C footprint of WOR including emissions from added machinery is essential to more accurately predict the mitigation potential of this practice. Biomass recycling improves soil health metrics In addition to contributing to achieving the long-term objective of limiting the global tempera- ture increase, these changes in soil C were also crucial to improve soil fertility and functioning as a living ecosystem. Large additions of C as woody residues resulted in a higher soil health index and biological activity as represented by significant increases in microbial biomass, potential activity of soil enzymes, and microbial respiration. Decomposition of woody biomass releases substantial amounts of C into soil, where it is subsequently used to fuel microbial metabolism and cell production [53]. CB, an enzyme involved in cellulose hydrolysis, is essen- tial in woody biomass decomposition. BG is a key member of the cellulase class of enzymes and completes the final step during cellulose hydrolysis by converting cellobiose to glucose [54]. Additions of woody biomass, composed of about 40% cellulose by weight, increased CB and BG potential activity under WOR. We found the same significant trend in the potential

Fig 4. Effect of Grind and Burn treatments on (a) Cellulase (CB); (b) β -glucosidase (BG); (c) β-N-acetylglucosaminidase; (NAG), and (d) Leucine Aminopeptidase (LAP) enzyme activities. (�) indicate significant differences at P �0.05. https://doi.org/10.1371/journal.pone.0229588.g004 PLOS ONE Whole orchard recycling PLOS ONE | https://doi.org/10.1371/journal.pone.0229588 March 27, 2020 13 / 22