Organic matter
Organic matter is the soil’s reserve and buffer, not the name of a microbial product.
Also called: organic matter, organic carbon, OM
- Organic matter is the soil’s reserve and buffer.
- It is not the name of a microbial product.
- Do not mix percent with grams per kilogram.
- Pale dusty soil that loses fertiliser after rain is thin.
- Residue return is year-by-year work.
- Fresh manure against the root burns.
How it appears on the sheet
Organic matter or organic carbon. g/kg versus % — 1.2% is not 1.2 g/kg.
A sketch. Do not fertilise from the picture alone.Common units
Often g/kg; some labs use %.
Soil:water ratio · Organic carbon and organic matter are not the same cell. Read the column name.
How to read the number
Organic matter is the soil’s savings, not a microbe bag. Residue return is slow work.
Sandy soils hold less. Fresh manure against the root burns. Rates live in the organic-matter guide.
Thresholds only, not a prescription. Rates live in the field guide. This page does not hand you a bag count.
| Cell | Low | Mid | High |
|---|---|---|---|
| Topsoil OM (sketch) | Pale, dusty, fertiliser vanishes | Clods then crumbles | Dark savings — still read salt and pH |
Regional classes differ. This table is a comparison, not a prescription.
What it looks like in the field
A pale, dusty handful that will not clod, and fertiliser that vanishes after rain, often means thin organic matter.
Don’t do this
- Don’t mix carbon with matter.
- Don’t expect a microbe bag to rebuild a field in one season.
- Don’t bury fresh manure on the root.