Effect of slope position on physico-chemical properties of eroded soil

The research work was conducted on eroded soil (Missa Series) in Samarbagh, District Lower Dir to determine the effect of slope position on soil physico-chemical properties. Soil samples were collected from top-slope, mid-slope and bottom slope positions at horizon-A, B and C. Results showed a significant difference among the physico-chemical properties of top, mid and bottom slope soils. Bulk density of the top-slope (1.51 g cm-3) was the highest followed by mid (1.39 g cm-3) and bottom slopes (1.32 g cm-3). Conversely, electrical conductivity EC-2.47 dS m-1), phosphorus (3.40 mg kg-1), Potassium (118.8 mg kg-1), Organic matter content (1.52 %), clay content (20.39 %) and silt content (49.17%) were the highest at bottom slope followed by mid and top-slopes, respectively. Soil A, B and C horizons were also significantly (p<0.05) different in their physico-chemical properties. Mean values showed that horizon Ap had the highest bulk density (1.43 g cm-3) and lower electrical conductivity (1.74 dS m-1), phosphorus (2.29 mg kg-1), potassium (84.86 mg kg-1), organic matter (1.08%), clay (12.83%) and silt content (40.49%) than both the B and C horizons. The deterioration in physico-chemical properties of top slope as compared to mid and bottom slopes and that of Ap horizon as compared to B and C horizons were presumed to be due to past soil erosion effect that removed the finer soil particles including soil organic matter and other plant nutrients. This study concluded that increasing extent of erosion due to slope effect can further deteriorate soil properties. The control of such damaging effects would require soil conservation strategies such as proper land levelling, afforestation, terracing and inclusion of restorative crops in cropping systems on these lands.