The slow turnover of soil organic carbon (SOC) in drylands has led to the proposition that these ecosystems can serve as significant carbon sinks to mitigate greenhouse gas emissions. This study aims to provide a quantitative assessment of the carbon sequestration potential of soils in dryland Israel.
We integrated data from a climate gradient study of SOC in forested and non-forested rangelands across Israel with geospatial information on land use and soil texture in the Negev Desert. To enhance understanding and estimate carbon storage capacity, we partitioned SOC into mineral-associated organic carbon (MAOC) and particulate organic carbon (POC).
Along the climate gradient, SOC increased nearly monotonically with precipitation. In the drier areas, MAOC comprised over 90% of SOC, but as SOC increased MAOC appeared to approach saturation, so that POC became an increasingly larger component of total SOC. The MAOC capacitance, based on topsoil samples (0–2 cm), was estimated at 48 g C kg⁻¹ silt+clay—comparable to global estimates. Applying this value to the Negev’s agricultural lands yielded an estimated MAOC capacitance of 19.5 Mt CO₂-equivalent, mostly in field crops. This represents about 25% of Israel’s annual emissions, suggesting that storing carbon as MAOC offers limited mitigation potential. Moreover, the negligible POC levels even in forested dryland sites suggest that strategies relying on POC accumulation may also have limited potential in these ecosystems. Together, these findings underscore the need for novel strategies to reach substantial carbon capturing in dryland soils.
