Implementation of Land Rehabilitation to Reduce Soil Erosion and Surface Runoff by Sengon (Falcataria oluccana) and Jabon (Antocephalus cadamba) Plantation

Abstract

Land productivity and stability can be reduced due to damaged watershed systems and increased surface runoff and erosion in soil. Unsustainable land management is one of the factors affecting land degradation, most of the decreased quality of the land is caused by soil erosion. Implementations of land rehabilitation and soil conservation especially to prevent the soil from erosion rates in some degraded land. The aim of this study was to determine the amount of surface runoff and erosion which potentially occurred on the vegetatively rehabilitated land by sengon and jabon plantation. The study was established on open land in the Education Forest of Forestry Faculty, Mulawarman University, Samarinda, East Kalimantan. The erosion measuring plots (EMP) were prepared at open land with the presence of sengon and jabon at different slope classes. Two plots with the size of 10 m x 4 m were made for each combination used. At the lowest part of the EMP, a paralon pipe was then installed to channel surface runoff and eroded soil into the storage drum. Hydro-orological parameters, including rainfall, surface runoff (only water mass measured), potential erosion rate (A), erosion hazard class (EHC), erosion hazard level (EHL), and depth of soil solum, were observed. The amount of surface runoff at the land planted with sengon and jabon showed different values regarding the slope classes and plant age. At the slope classes of rather steep, the surface runoff was lower than that of steep even at both 1 year and 2 years of planting age. The potential erosion that occurred in the area planted with sengon in the slope class of rather steep and steep at plant age was still lower than 15 ton ha-1year-1, indicating that the erosion hazard level was low. A similar condition was found at land planted with jabon at rather steep. On the other hand, land planted with jabon in steep slope classes both 1 year and 2 years showed potential erosion > 15 ton ha-1year-1 (EHL was low). This study suggested that sengon and jabon could be potentially utilized to reduce runoff rates and eroded soil mass for water and soil conservation in the future.