Role of coffee plantation in reducing erosion under coarse textured soil in wet tropical region

Abstract

Water erosion is one phenomenon causing land degradation in a wet area. The research was aimed to evaluate the total of soil erosion under coffee plantations having coarse textured soil in wet tropical regions. This research was taken out on a coffee plantation in Sibarasok, Maninjau having rather to very steep slope and high annual rainfall, with Inceptisol soil order. Soil samples were taken from 6 land units (Coffee-86 y having 0-8%, 25-45%, and >45%, Coffee 5 y-15-25%, Coffee 8 y-25-45%, and forest >45% as control). The samples of soil were prepared and analyzed in the Laboratory of Soil, Department of Soil Science and Land Resource, Andalas University. The actual amount of soil eroded was predicted using the USLE formula. Then, it was compared to the tolerated (Etol) soil erosion. The result showed that the predicted amount of soil eroded was quite low (<10 T/Ha/y), except under coffee having >45% slope. The highest soil eroded in the very steep slope was due to its low SOM content and permeability, with an erosion hazard level of 1.2. Compared to tolerated erosion (Etol), the actual soil erosion predicted was lower than the Etol. The fiber roots of the coffee dominating the top 5 cm of soil surface as well as high SOM content and hydraulic conductivity rate caused the soil on the top to become tightly held avoiding erosion.