5. Glossary

Organic carbon stock

Total amount of organic carbon contained in a given volume of soil. Stock size is expressed in kg.m ⁻² or t.ha ⁻¹ at a given depth.

Primary production

Formation of organic matter from mineral matter using energy. It takes place mainly by photosynthesis and is expressed in mass of carbon per unit time.

Root exudates

Organic matter released through plant roots. Can consist of dead cells, macromolecules, or small molecules. Root exudates make up a significant fraction of net primary production (5–30%).

Plant litter

All decomposing plant detritus. There is aerial litter (leaves, stems)...