| Value | Category |
|---|---|
| 1 | Erosion |
| 2 | Continuous cultivation |
| 3 | Overgazing |
| 4 | Absence of crop rotation |
| 5 | No idea |
| 6 | Others |
| 7 | Continous application of fertilizer |
| 8 | Never use manure |
| 9 | Planted eucalyptus tree around the land |
| 10 | Change of climate/shortage of rain |
| 11 | Never use fertilizer |
| 99 | Don't know |