Environmental Engineering Reference
In-Depth Information
Table 15.2 Nitrogen, phosphorus, and potassium contents of the leaves of the four
indigenous trees
Nutrient
Faidhebia
Diospyrum
Vitellaria
content
albida
mespiliformis
paradoxa
Parkia biglobosa
Total nitrogen %
2.85
1.45
1.75
1.70
Total phosphorus %
0.60
0.45
0.55
0.44
Potassium (mg/kg)
1,152.0
1,132.0
688.0
635.0
N/P ratio
4.75
3.22
3.20
3.95
properties in between tree canopies and the open grassland for both soil types
were largest in
D. mespiliformis
, followed by
P. biglobosa
,
F. albida
, and
V. paradoxa
in that order.
Soil chemical properties under tree canopies and in open grassland
Comparison of chemical properties of soils under tree canopies and under
open grasslands was initially done for each indigenous tree under luvisol and
gleysol separately. In all cases, all chemical properties except C:N ratio were
higher under tree canopies than in open grassland. When the data were put
together to provide an overall comparison under luvisol (Table 15.3) and
gleysol (Table 15.4), soil pH values under all trees for both soil types showed
that the soils were weakly acidic (pH 5-6). Soil pH values under tree canopies
were significantly higher than in the open grassland in luvisol (Table 15.3), but
not significant in the gleysol (Table 15.4). Soil organic matter and total nitro-
gen content under tree canopies were significantly higher than in the open
grassland in both soil types. There was no significant difference in the
carbon:nitrogen (C:N) ratio between the two soil types under tree canopies or
in the open grassland. There was no significant difference in available soil
phosphorus in the gleysol between the tree canopies and the open grassland.
However, the differences were significant in the luvisol. The content of soil
exchangeable cations, calcium, magnesium, potassium, and sodium in both
soil types under the tree canopies was higher than in the open grassland
(Tables 15.3 and 15.4). It was significant for all elements on both soil types
except potassium in gleysol (Table 15.4). The total exchangeable bases content
followed the same trend as the individual cations. It was higher under tree
canopies than in the open grassland, and the difference was significant for all
trees in both soil types. Cation exchange capacities under tree canopies were
higher than in the open grassland for both soil types.
