Reducing Runoff and Erosion to Improve the Strength of Soil Derived from Pumice Tuff in Patamuan, West Sumatra, Indonesia.

Erosion and landslides that occur in volcanic areas of Indonesia are crucial problems that cannot be overcome completely. This study was designed to determine the ability of different plant types to reduce water runoff and soil erosion and improve soil physical properties. Soil samples were taken from landslideprone areas in Patamuan, West Sumatra. Plots created from steel plates of 1.5 x 0.5 x 0.3 m in dimension and set at 22° angle, were placed in the greenhouse and a rain simulator was used to irrigate the plots. The experiment was a completely randomised design with three replications. The plant types were Tithonia shrub, vetiver, king grass and Napier grass. Results showed that runoff and soil erosion were reduced from 93 to 74 liter/m2, and from 1.03 to 0.17 kg/m2, respectively. Planting Tithonia decreased runoff while Napier grass reduced soil erosion. Soil moisture content at field capacity increased from 14% to 20%, and macropores from 31% to 41%; however there was a decrease in micropores from 17.5% to 14%. King grass increased root density (RD) and root area ratio (RAR), but reduced the relative soil particle detachment rate (RSD). King grass and vetiver had a positive impact on reducing both runoff and soil erosion. [ABSTRACT FROM AUTHOR]