What needs to be clarified
Check which carbon form the laboratory measured, whether carbonate carbon was accounted for and whether conversion to organic matter is justified for these soil samples and method.
Materials to prepare
- Soil samples with recorded sampling depths and locations
- Carbon determination report describing pretreatment
- Liming records and organic matter calculation with its conversion factor
What to compare
Establish whether total or organic carbon was measured and how inorganic carbon was determined or removed. Review dry-mass reporting, controls and the conversion factor. Compare depths and sample composition, separating carbonate contribution and calculation limitations; total carbon growth is not automatically humus growth.
Possible outcome of the analysis
A verification table may show carbon forms and conversions, identify unsupported assumptions and propose further analysis where the original method did not reliably separate the organic fraction.
Limits of the conclusions
One indicator establishes neither fertility, persistent carbon accumulation nor a liming effect. Findings concern the samples and cannot confirm stock changes without bulk-density and depth data.