Abstract:
The present investigation was carried out in order to assess the soil development o f a
human impacted site located near Kamburupitiya in the Matara district. The site
previously under cinnamon cultivation was severely affected by the Nilwala Ganga Flood
Protection Scheme in 1987. The soil has been cut down to the bed rock and removed from
the site in order to construct dams. Representative soil samples (from 0-15 cm depth) were
drawn randomly from the disturbed site and analyzed for pH, EC, bulk density, N, P, K
and organic matter contents using standard methods. A neighboring site with the same
soil type was used as the reference in order to compare the disturbed and undisturbed
soils. Results revealed that the average bulk density, pH and EC o f the disturbed soil were
1.25 g/cm3, 5.35 and 36.25 p mhos/cm respectively. Whereas the corresponding values for
the undisturbed soil were 0.87 g/cm3, 5.23 and 56.2 p mhos/cm. The values o f major
nutrients (N, P and K) were 0.0088 %, 10.5 and 72.66 mg/kg for the disturbed soil and
0.095 %, 44 and 82.8 mg/kg for the undisturbed soil. The average organic matter contents „
o f the disturbed and the undisturbed soil were 0.24 and 1.09 % respectively. The
observation made during the study revealed that the soil surface had been totally exposed
due to severe erosion and therefore, the major reason for the significantly lower values of
nutrients (organic matter, N, P and K) recorded in disturbed soil would be removal o f the
bulk o f nutritive soil byerosion. Furthermore, the present findings indicate that even 18
years after the disturbance the development o f soil was quite poor and thus it may take
some considerable period o f time to improve the soil for crop production.
