Table 1 Different methods of soil carbon determination used in referred authors
Methods* | Number of observations | Percentage proportion (%) |
|---|---|---|
Ex-situ methods: | ||
 1. Walkley and Black Method  (Wet oxidation or combustion) | 21 | 58.2% |
 2. Dry combustion method: CN analyser | 9 | 25% |
 3. Dry combustion: weight-loss-on-ignition | 2 | 5.6% |
In-situ methods (in combination with Ex-situ methods): | ||
 4. Isotope ratio mass spectrometer | 1 | 2.8% |
 5. Dry combustion coupled Infra-red spectroscopy  Isotope mass spectrometer | 2 | 5.6% |
 6. Walkley and Black Method coupled  Reflectance spectrometer | 1 | 2.8% |
Total | 36 | 100 |