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

Abstract

There is an urgent need to develop climate smart agroecosystems capable of mitigating climate change and adapting to its effects. In California, high commodity prices and increased frequency of drought have encouraged orchard turnover, providing an opportunity to recycle tree biomass in situ prior to replanting an orchard. Whole orchard recycling (WOR) has potential as a carbon (C) negative cultural practice to build soil C storage, soil health, and orchard productivity. We tested the potential of this practice for long term C sequestration and hypothesized that associated co-benefits to soil health will enhance sustainability and resiliency of almond orchards to water-deficit conditions. We measured soil health metrics and productivity of an almond orchard following grinding and incorporation of woody biomass vs. burning of old orchard biomass 9 years after implementation. We also conducted a deficit irrigation trial with control and deficit irrigation (-20%) treatments to quantify shifts in tree water status and resilience. Biomass recycling led to higher yields and substantial improvement in soil functioning, including nutrient content, aggregation, porosity, and water retention. This practice also sequestered significantly higher levels of C in the topsoil (+5 t ha -1 ) compared to burning. We measured a 20% increase in irrigation water use efficiency and improved soil and tree water status under stress, suggesting that in situ biomass recycling can be considered as a climate smart practice in California irrigated almond systems.

Nutrient dynamics from surface‐applied organic matter amendments on no‐till orchard soil

“…OMA use has been shown to reduce tree water stress and increase soil water‐holding capacity. (Jahanzad et al, 2020; Lepsch et al, 2019; Walsh et al, 1996). In contrast, in a study comparing irrigated and non‐irrigated crops, manure did not alter the water‐holding capacity of three different soils (Wu et al, 2003).…”

Effects of whole‐orchard recycling on nitrate leaching potential in almond production systems

“…This is likely attributed to an increase in microbial biomass C, associated with the substantial input of orchard biomass, and the stoichiometric necessity of assimilating additional N to balance the C/N ratio requirements of biomolecule synthesis. This is supported by a well-documented positive correlation between soil microbial biomass C and MBN across studies (Geisseler et al, 2010;Jahanzad et al, 2020). Thus, the increase in sustained soil microbial growth of the +biomass treatment and immobilization potential is likely associated with the additional energy and nutrients of incorporated orchard biomass within the topsoil (Bonanomi et al, 2011;Throckmorton et al, 2012).…”

“…At the main plot level, two biomass management treatments were established: a whole-orchard recycling treatment (+biomass), where the woody biomass was incorporated within the top 15 cm of soil in the tree row prior to planting by using land clearing equipment (Ironwolf 700B Slasher), which produced variable sizes of woody biomass ranging from ∼5 to 30 cm and a control treatment (−biomass), where trees were uprooted, burnt, and ashes reincorporated to the surface soil. Details of the trial design, establishment, and management can be found in Jahanzad et al (2020). At the short-term experiment (Lincoln), soil treatments were established in 2017 after termination of a 20-yr-old Westerner plum (Prunus salicina Lind) orchard in a complete randomized design with four replications.…”

A review of the global climate change impacts, adaptation, and sustainable mitigation measures

“…Adaptation and mitigation are the crucial factors to address the response to CC (Jahanzad et al 2020 ). Researchers define mitigation on climate changes, and on the other hand, adaptation directly impacts climate changes like floods.…”

“…Researchers define mitigation on climate changes, and on the other hand, adaptation directly impacts climate changes like floods. To some extent, mitigation reduces or moderates greenhouse gas emission, and it becomes a critical issue both economically and environmentally (Botzen et al 2021 ; Jahanzad et al 2020 ; Kongsager 2018 ; Smit et al 2000 ; Vale et al 2021 ; Usman et al 2021 ; Verheyen 2005 ).…”