Abstract:
Calotropis procera is a wild species that is drought-resistant and plays a number of
economic and ecological uses. The species is important in soil fertility improvement,
pollution control by monitoring sulphur dioxide emissions in the air and suitable indicator
of exhausted soil. This study was undertaken in drylands of South Eastern Kenyato
evaluate the species‟ soil ecology and ability to bioaccumulate heavy metalsThe objectives
of the research were to determine the soil chemical and physical properties for survival of
C. procera and to determine the ability of C. procera in phytoextraction of heavy metals
from the soil. To understand the soil chemical and physical properties for growth of C.
procera, two sites namely a farmland and a natural stand of C. procera were used. In the
two sites, soil samples were collected and analysed for soil pH, total N, P, K and bulk
density. C. procera tissues (leaves) were harvested and analyzed for total N, P, K, OC, Zn,
Mn, Cu and Fe. One-way ANOVA was applied to assess the significance of variations in
the soil chemical properties (pH, total N, P and K), Plant tissue data (total N, P, K, OC, Zn,
Cu and Fe), C. procera provenances and spacing variables in relation to the field plots.
Pearson simple linear correlation coefficient (r) was calculated for assessing the type of
relationship between the study site and the natural stand of C. procera in relation to the
soil chemical properties. There were no significant differences in subplots soil chemical
properties. Correlation analysis showed a strong positive spatial relationship (Pearson,
P<0.01, rs = 0.734) in soil chemical properties between the artificial and the natural stand
of C. procera. Further, there were no significant differences (p<0.05) in soil pH as well as
in bioaccumulation of heavy metals in both the artificial and natural stands of C. procera.
However, Pearson correlation analysis showed a very strong relationship (Pearson, P<0.01,
rs = 0.966) in terms of pytoextraction/phytoaccumulation of heavy metals (Zn, Mn, Cu and
Fe) between the artificial and natural stands of C. procera. The study concluded that C.
procera can grow in a wide range of soil pH levels and the species has the ability to
bioaccumulate heavy metals in its leafy tissues. The study recommends use of C. procera
as a remediator of soils contaminated with heavy metals (Zn, Mn, Cu and Fe).