| Fertility attributes | Sites with sedimentary parent materials | % Lim. | Sites with volcanic parent materials | % Lim. | |||||||||||
| Mondoni | Essoasso | Kumbe | Illoani | Dieka | Mafanja | Likomba | Boa | Meme | Bakingili | Debundscha | Mbonge | Bota | |||
| pH | − | − | + | + | − | − | − | − | + | 33.3 | − | − | − | − | 0.0 |
| OC (%) | − | − | − | + | − | + | − | − | + | 33.3 | − | − | − | − | 0.0 |
| CEC (meq/100g) | − | − | + | + | + | + | + | + | + | 77.8 | + | − | − | − | 25.0 |
| BS (%) | − | + | − | + | − | + | − | − | − | 33.3 | + | + | − | − | 50.0 |
| Mg: K ratio | − | − | + | − | − | + | − | − | + | 33.3 | − | − | − | + | 25.0 |
| K mole fraction | + | + | + | + | + | + | + | + | + | 100.0 | + | + | + | + | 100.0 |