The indicator represents the stocks of soil organic carbon (Corg) or the content of soil organic matter (SOM) in agricultural land soils to a depth of 30 cm. The indicator displays:

• Average Corg content measured in soil samples at representative locations in the considered land uses of agricultural land.
• Average Corg stocks in soil (modeled values) in the considered land uses of agricultural land.

Both indicators consider selected agricultural land uses according to the RABA classification (MKGP 2022): arable land, vineyard, intensive orchard, extensive or grassland orchard, permanent grassland, marsh meadow, land undergoing afforestation, trees and shrubs.

Measured Corg content at representative locations and the estimation of Corg stocks in agricultural land are ultimate indicators of sustainable agricultural soil use, ensuring/maintaining fertility, and contribution of agriculture to the climate change mitigation

The content of soil organic matter (SOM) is the ultimate indicator of both agricultural and ecosystem soil quality. Soil fertility, crop yields and the success of agricultural production and husbandry are directly linked to the content of SOM. This important parameter is the carrier of the soil's ability to provide essential soil ecosystem services (SES) – services that soils perform in the environment. SES provide benefits to humans, animals, and other segments of the environment. Key environmental SES include soils as a carbon sink, thereby mitigating CO₂ in the atmosphere; filtration, purification, and enrichment of water, thereby supplying groundwater with drinking water; retention and degradation of pollutants; retention, binding, release and cycling of macro and micro-nutrients; support for soil biodiversity and the abundance of soil biota.

Sustainable agricultural production and the contribution of agriculture to environmental protection and climate change mitigation are expressed through care for appropriate, and where possible, increased levels of SOM in the upper soil horizons.

The results of soil sampling and research in Slovenia confirm suitable or, in comparison to some other European countries, increased levels of SOM in agricultural lands. The average content of organic carbon in soils (Corg) in agricultural soils is highest in the upper soil horizons at depths of 0–10 cm (3–7%) and decreases with depth. At a depth of 20 to 30 cm, Corg content ranges from 2 to 3%. The highest Corg stocks in soils are in areas with trees and shrubs (DG), while the lowest are in vineyards (VI).

The average Corg stocks in the treated agricultural lands (KZ) to a depth of 30 cm was 92.9 t/ha, with the highest in the soils of marsh meadows – 197.0 t/ha. In soils with extensive use, including extensive orchards (ES), permanent grasslands (TR), land undergoing afforestation (ZR), and KZ overgrown with trees and shrubs (DG), Corg stocks ranged from 92.2 to 109.4 t/ha. Corg stocks in vineyard soils (VI), intensive orchards (IS), and arable lands (NJ) ranged from 60.0 to 92.7 t/ha.

Nevertheless, researchers believe it is still possible to increase SOM content in certain areas of Slovenia (e.g., Drava-Ptuj Field, Mura Plain, Vipava Valley) and certain land uses (e. g. vineyards, arable lands, intensive orchards).

Conventional treatment of KZ (e.g., intensive cultivation, deep plowing, and the use of only mineral fertilizers) increases greenhouse gas emissions from the soil (CO₂).

Conservation (i.e., reduced, or minimal) soil treatment and/or increased organic matter input into the soil leads to greater Corg accumulation in the soil and consequently reduces the amount of CO₂ in the atmosphere, contributing to medium and long-term climate change mitigation.

Efforts are being made to ensure that Common Agricultural Policy measures are directed toward promoting sustainable agricultural practices, better environmental protection, and a greater contribution of agriculture to climate change mitigation.