Table 2.
Soil N stocks and vegetation N stocks for pastoral systems in sub‐Saharan Africa (SSA).
| Ecosystem compartments | Stock | References |
|---|---|---|
| Soil N stock (0–100 cm) in open areas (Mg N/ha) | 4.9 ± 4.0 | calculated from Leenaars (2013) |
| Soil N stocks underneath trees (Mg N/ha) | 9.8 ± 8.0† | Bernhard‐Reversat (1982) |
| Total soil N stocks (Mg N/ha) | 5.3 ± 4.3 | – |
| Grass biomass (kg/ha) | 2,980‡ | Wang et al. (2012) |
| Grass N content (% DM) | 0.53§ | Knox et al. (2011) |
| Total Grass N stock (kg N/ha) | 12.6¶ | – |
| Tree N stocks (kg N/(ha of canopy cover)) | 301.7 ± 35.6# | Bernhard‐Reversat and Poupon (1980) |
| Tree N stock (kg N/ha) | 27.0 ± 3.2|| | – |
| Total N vegetation stock (grass + trees) (kg N/ha) | 39.6 ± 3.2 | – |
| Total N stock (soil + vegetation) (Mg N/ha) | 5.4 ± 4.4 | – |
Values are mean ± SD. DM, dry mass.
†
Calculated assuming soil N stock doubles in the area underneath the trees to be applied in 9% (900 ha) canopy cover calculated from satellite imagery.
‡
Value for grazed pasture in a Namibian savanna.
§
Value from grass samples in a South African savanna.
¶
Value calculated for 80% cover (i.e., 8,000 ha) calculated from satellite imagery.
#
Mean value from 12 Senegalia senegal samples in a Sahelian savanna.
||
Calculated for 9% canopy cover (i.e., 900 ha) calculated from satellite imagery.