Soil condition (Global Soil Organic Carbon)

Source: FAO Global Soil Organic Carbon Map (GSOCmap) Year: 2019 Category: Physical risks · Enabling services · Soil condition Coverage: Global Format: Raster grid (~1 km) Used in risk analysis: Yes — gates Enabling services

What it shows

This layer maps soil organic carbon, a core indicator of soil condition and fertility. Soil organic carbon underpins the capacity of soils to retain water and nutrients, support plant growth and resist degradation. It matters for nature-related risk because depleted, degraded soils undermine agricultural productivity and the wider services that healthy land provides.

How it is built

The layer is the Global Soil Organic Carbon Map (GSOCmap), the first global soil organic carbon map produced through a participatory process led by member countries under the Intergovernmental Technical Panel on Soils and the Global Soil Partnership Secretariat. Countries agreed a shared methodology, prepared national maps using modern tools, and the Global Soil Partnership then gathered and harmonised these into a single global product. The measured variable is the stock of organic carbon held in the soil, compiled at fine spatial resolution and accompanied by a technical report describing the methodology.

How to read it

Higher values indicate soils richer in organic carbon, generally signalling healthier, more resilient land. Lower values indicate carbon-depleted soils, which tend to be more vulnerable to erosion, reduced fertility and degradation. Because the layer reflects condition rather than a hazard, low values are the signal of concern for site screening.

Class thresholds

The underlying layer models a physical quantity: soil organic carbon stock, in tonnes per hectare (t/ha) — the mass of organic carbon held in the soil per unit area, from the GSOCmap product. Because this is a condition rather than a hazard, the risk classes run in reverse: low carbon is high risk. The five classes map to the following thresholds:

A site is flagged on the Enabling services dimension when soil organic carbon falls below 50 t/ha (i.e. it reaches the High-risk class or worse) and the entity's "Soil quality regulation" ENCORE pressure is material.

How these thresholds were set. The GSOCmap supplies the underlying carbon stock in t/ha; the five-class split at 30 / 50 / 70 / 90 t/ha is a Darwin in-house classification using fixed round-number cutoffs on that quantity. The breaks are not derived from WWF or any other published soil-condition standard.

Source

Global Soil Organic Carbon Map (GSOCmap), Global Soil Partnership and Intergovernmental Technical Panel on Soils, distributed via SoilWise.

Comparison with the WWF Risk Filter Suite

This maps to the WWF Biodiversity Risk Filter indicator S2_1 Soil Condition and is aligned in concept. WWF builds its soil-condition indicator from SoilGrids 2.0 soil organic carbon (Poggio et al., 2021); Darwin uses the GSOCmap. Both rely on the same variable family — soil organic carbon — so the two are directly comparable, differing mainly in the underlying compilation.

Risk analysis

A site is flagged on a dimension by combining a proximity trigger (this layer) with an activity trigger (the entity's ENCORE pressure/service). Proximity only → Potentially material; proximity and the matching ENCORE pressure/service is material → Very material; neither → Not material.

Legend

Symbolised field: Risk category (t/ha average SOC)

Generated from darwin/layers/layer-soil-condition-global-soil-organic-carbon.toml and risk_indicator_pairs.toml (develop).