Global Distribution of Plant-Extractable Water Capacity of Soil

8.6 cm is the global average plant-extractable water capacity of soil, excluding Greenland, Antarctica, and bare soil areas. This dataset provides a global estimate at a 0.5 x 0.5 degree grid resolution, derived from FAO/Unesco soil maps, climate-based organic matter estimates, and vegetation rooting depths. The estimates reflect the combined influence of soil texture, organic content, and plant root or profile depth.

Use Cases

• Modeling evapotranspiration demands based on spatially-variable soil water capacity.
• Assessing regional agricultural drought risk using integrated soil texture and root depth data.
• Validating land surface models that assume invariant soil water parameters.
• Studying the global distribution of soil water resources available to vegetation.

Strengths

• Provides a global estimate with a specific reported average of 8.6 cm.
• Integrates multiple authoritative sources: FAO/Unesco soil maps, climate data, and vegetation characteristics.
• Quantifies spatial distribution, stating estimates are less than 5 cm over approximately 30% of vegetated area.

Limitations

• Key metadata conflicts: 'last updated' dates are 1996-12-31 on one platform and 2026-04-10 on another, creating uncertainty about data currency.
• Specific column names and dataset size (rows, file size) are not provided in any source.
• The description notes the root depth parameter, which limits the calculation, is the most influential and uncertain.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Representative soil profiles were created for FAO/Unesco soil units; soil organic matter was estimated from climate data; rooting depths were obtained from a vegetation dataset.

Freshness

Conflicting: 1996-12-31 (nasa_earthdata) and 2026-04-10 (datagov).

Geography

Global (0.5 x 0.5 degree grid), excluding Greenland, Antarctica, and bare soil areas.