It is the classification used by the INTA soil survey map, taken from the United States Department of Agriculture system. It organizes the land into eight classes according to how much its agricultural use limits: class I is land that can be worked without further care and class VIII has no agricultural aptitude of any kind.
It does not measure how much a specific crop yields. Measure what can be done with the paddock in a sustained manner: if it can tolerate continuous agriculture, if it only tolerates occasional agriculture, or if it spends its life in grazing. That's why it's the first number someone who buys looks at.
The eight classes
| Class | What this means |
|---|---|
| Yo | Suitable for agriculture without major limitations |
| II | Suitable for agriculture with slight limitations |
| III | Suitable for agriculture with moderate limitations |
| IV | Occasional agriculture; severe limitations |
| V | Livestock aptitude; not suitable for continuous farming |
| VI | Livestock aptitude; not suitable for continuous farming |
| VII | Limited or forest grazing only |
| VIII | Without agricultural aptitude |
On the map the scale has six steps and not eight: with eight shades of the same green the light end does not reach the minimum contrast against the satellite image. The pairs that share real use are grouped together—V and VI are the two ranchers, VII and VIII are marginal—and the legend says so explicitly, so that the grouping is not hidden.
The letters that accompany the number
A class almost never comes alone: it is written "IIIw" or "VI cs". The letters are the limitations, that is, the reason why that land is not class I.
| Letter | Limiting |
|---|---|
| and | Erosion risk |
| w | Excess water |
| yes | Limitations of soil |
| c | Climatic limitations |
The distinction matters when purchasing: a class III due to excess water can be corrected with drainage and systematization, and a class III due to limitations of soil itself, cannot. It is the difference between an investment and a roof.