Enhancing Carbon Sequestration in Mediterranean Agroforestry Systems: A Review

Abstract

The agroforestry systems with a high potential for C sequestration are those degraded by poor management strategies. Studies on changes in soil C status in these ecosystems mostly take into account labile C pools. Labile and stable soil organic matter (SOM) fractions are affected by soil management and land-use changes. Stable C pools are essential to understanding effects of land-use on soil C storage in the long term. The SOM stability is partly enhanced by the interaction of SOM with minerals and its inclusion into soil aggregates. Recalcitrant substances (e.g., lignin and chitin) also contribute to the passive SOM fraction. Macroaggregates mostly reflect the influence of plant roots and coarse intra-aggregate particulate SOM (POM), whereas microaggregates reflect the influence of fine interaggregate POM, clay concentration and humified SOM fraction. Often, POM is more sensitive to soil management changes than total SOM. Glomalin is a recalcitrant protein consisting of chitin produced by mycorrhizal fungi to protect hyphae. Glomalin has implications on C sequestration in agroforestry soils, but further research is needed before any prediction can be made. One challenge is reducing the CO2 emission from roots, and increasing the recalcitrant root C.

Crop diversification effects on soil organic carbon and nitrogen storage and stabilization is mediated by soil management practices in semiarid woody crops

“…Although the agro-environmental benefits of crop diversification, including promising soil carbon sequestration rates and fertility maintenance, have been worldwide reported (Paustian et al, 1997;Abdalla et al, 2014;Tamburini et al, 2020;Carranca et al, 2022) (Yan et al, 2022), there is a need for improving our understanding of the different SOC and nitrogen (N) stabilization mechanisms fostered by inter-cropping and how local environmental and management conditions influence the efficiency of the SOC and N sequestration process (Six et al, 2002;DeGryze et al, 2004), particularly in semiarid regions (Blanco-Canqui and Lal, 2004;Hobley et al, 2018;González-Rosado et al, 2022;Sánchez-Navarro et al, 2023). Therefore, the analysis of the different mechanisms favouring SOC and N storage and stabilization in semiarid soils is a stepping stone to understand how C and N fluxes may be affected by different agricultural management scenarios, and will contribute to identify early warning indicators as well as to design sustainability metrics tailored for these dry regions.…”