Abstract:
:The study was aimed to investigate soil organic carbon (SOC) and total nitrogen(TN) dynamics among different
land use systems in the Essera district of Dawuro zone, southwestern Ethiopia. Landscape of the district was dominantly
covered with enset (Ensete ventricosum) farming system. For this study, three representative land use types namely, Enset farm,
woody and cultivated lands were considered. For each land uses, a plot of 25x25m size was marked as a sample plot to collect
soil samples in an‘X’ design (from the middle and four corners of the plot). Accordingly, both composite and core sampled
soils were gathered from the five subsequent soil depths (i.e.0-5, 5-10, 10-15, 15-20 and 20-25cm). Consequently, analysis of
variance were conducted by using SAS version 9.2. Moreover, a mean separation for each parameter was made using LSD
(Least Significant Difference) test. The result confirmed that soil organic carbon (SOC), total nitrogen(TN) stock were
significantly influenced by topographic variation, landuse types and soil depth. The highest SOC and TN stocks were observed
in the lower slope position, enset farm land and upper soil depths. Regarding to land use difference, 18.65 and 13.50 t/ha SOC
stock were observed in the enset and cultivated farm land respectively. TN was also highest in the enset farm land as compared
with cultivated and woody land. In contrast, the lowest soil organic carbon stocks were recorded in the upper slope position, in
the cultivated land and lower soil depths. Both SOC and TN stocks were significantly decreased from the upper soil layers to
lower soil depths. Soil physical properties were also significantly influenced by topographic position, land use difference and
soil depths. Soil clay contents were highest in the enset and woody land while lowest in the cultivated land. However, soil bulk
density, soil silt and sand fractions were highest in the cultivated land. Moreover, soil clay content was significantly increased
from upper to lower slope position and vice versa for soil bulk density, soil silt and sand fraction. In conclusion, based on the
confirmed result, it deserves to improve soil fertility management under different land use types and slope categories, so that
soil organic carbon, total nitrogen and soil clay contents could be improved accordingly.
