3.3 Soil chemical quality indicators
Total Kjeldahl Nitrogen (g/kg) showed a statistically significant
difference between sites, where the nitrogen content was higher in the
CG sites than in the OG sites. Both Total Carbon and Total Nitrogen (%)
were higher in the CG sites, but no significant difference was found
(Table I). Available ammonium showed relevant differences among sites,
where the CG sites showed lower values than in the OG area. On the other
hand, nitrate was not significantly different. Total phosphorus (mg/kg)
was significantly different between sites, showing higher CG values than
the OG condition, mostly because of differences in the inorganic P
content. Organic P (mg/kg) was higher in the CG sites, but no
statistically significant difference was found. However, the organic P
fraction was significantly larger under canopy across grazing
conditions. Available Olsen P (mg/kg) was consistently lower in the CG
site than in the OG site.
On the other hand, mineralizable N was higher in the CG sites than in
the OG sites, but no statistically significant. Similarly, mean POXC/C
showed no statistically significant difference between conditions, but
it was significantly greater under the tree canopy condition. Soil pH
(H2O) showed a significant statistical difference
between conditions, where the pH values in the CG were less acidic than
in the OG site. The overall mean soil CEC was significantly different,
where the CG sites’ values were consistently higher than in the OG
sites. All exchangeable bases were markedly higher in the CG condition,
except for sodium that was higher under the OG condition.