Table 3.
Mean nitrogen density (Mg ha−1 of N) and total nitrogen stocks (Mg of N) by LULC class at the watershed scale
| LULC/LUCa | Descriptive statistic | |||
|---|---|---|---|---|
| Range of nitrogen density (Mg ha−1 N) | Mean nitrogen density (Mg ha−1N) (SE) | Total nitrogen stocks (Mg N) (SE) | ||
| Min | Max | |||
| Forest land | 740.37 ± 0.021 | |||
| Riparian forest and woodland | 0.170 | 0.285 | 0.212 (0.014) | 72.41 ± 0.014 |
| Savannah Woodland | 0.045 | 0.160 | 0.096 (0.005) | 530.79 ± 0.005 |
| Shrub Savannah | 0.008 | 0.064 | 0.032 (0.001) | 137.16 ± 0.001 |
| Grassland | 0.825 ± 0.0006 | |||
| Savannah grassland | 0.0001 | 0.0178 | 0.0085 (0.0068) | 0.825 ± 0.0.0006 |
| Cropland | 62.57 ± 0.0006 | |||
| Cropland and Fallow | 0.00018 | 0.0252 | 0.0077 (0.0067) | 62.57 ± 0.0006 |
| Settlements | 5.20 ± 0.002 | |||
| Settlements | 0.0017 | 0.0201 | 0.0106 (0.0021) | 5.20 ± 0.002 |
| Agroforestry | 1.53 ± 0.022 | |||
| Cashew plantation | 0.017 | 0.340 | 0.0741 (0.022) | 1.53 ± 0.022 |
| Plantation | 5.01 ± 0323 | |||
| Eucalyptus grandis | 0.012 | 1.091 | 0.321 (0.088) | 4.42 ± 0.088 |
| Tectona grandis | 0.058 | 0.418 | 0.291 (0.115) | 0.26 ± 0.115 |
| Azadirachta indica | 0.114 | 0.425 | 0.317 (0.101) | 0.23 ± 0.101 |
| Gmelina arborea | 0.024 | 0.079 | 0.058 (0.017) | 0.10 ± 0.017 |
The age of plantations and agroforestry system varied from 5 to 45 years which explained the large standard error (SE) and the large variance relative to the mean obtained from their plots data. The area of each LULC class was provided in the Table 1