Estimating the total soil organic carbon capturing potential of agriculture in Israel to inform country-wide carbon policy

Carbon capturing using modified agricultural practices appears to be a prominent strategy for climate mitigation, because the accrual of soil organic carbon (SOC) and its maintenance also provide many agronomic advantages. Previous studies have estimated the global SOC capturing potential as the gap between the mineral-associated organic carbon (MAOC) capacity—considered the upper limit for long-term SOC accrual—and current MAOC stocks, providing promising results. State-level estimates of SOC capturing potential using this methodology can better inform policy on how to maximize C capturing. Here we aimed at quantifying the current potential for SOC capturing in agricultural soils in Israel. Gridded geographical information on soil texture and land use was compiled for an area of 390,000 ha, encompassing field crops (180,000 ha), orchards (90,000 ha) and rangeland (110,000 ha). A bulk density-texture function was derived from published literature; and the typical capacitance for MAOC of the soils in Israel was estimated at a value of 48 g C kg^-1 silt+clay based on samples of the organic-rich top-soils in planted forest sites. The MAOC capacity to a depth of 20 cm in all the agricultural soils of Israel was estimated at a total of 25.1 Mt C (92 Mt CO₂-eq). Field crops were associated with the highest capacity followed by rangeland and orchards. In the field crops, the regions with the highest capacity were the Northern Valleys where clay-rich soils are abundant and the semi-arid Negev region, where the expansive agricultural land area compensates for the abundance of sandy soils. Sporadic information published from trials on field crops in the Northern Valleys and the Negev show that current SOC there only amounted to 41% and 30% of the estimated MAOC capacity for those sites (respectively). While the low SOC filling in the semi-arid Negev might carry promise for a large capturing potential, it also raises questions whether the hot climate does not further limit SOC to values below the MAOC capacitance. For orchards, scant data exists regarding current SOC levels. However, we propose that the possibility of storing SOC in deeper soil layers in orchards might offer substantial carbon storage potential at the national scale, a topic still requiring investigation. Overall, despite the uncertainty involved in this work, our study provides a foundational framework for policymakers to develop carbon management strategies in Israel, while highlighting knowledge gaps to guide future research.