Changes in Soil Chemical and Physical Properties of Andisols under Oil Palm Small holder in the West Pasaman District of West Sumatra

Monitoring the productivity and sustainability of oil palm plantations is very important to anticipate the possibly land degradation occurs. The objective of this research was to comprehend the influence of oil palm plant age on the change on soil chemical and physical properties in small oil palm plantation in West Pasaman district of West Sumatra. Field research was conducted from May to July 2016 by using survey method under 3 different plant ages (5-10, 10-15, and >15 years old) in 3 areas (Kinali, Pasaman, and Koto Balingka sub-district). The variables of this study consisted of soil chemical properties: SOM, CEC, pH, total N, available-P, exchangeable base cations (K, Ca, Mg and Na-exch.); physical properties: bulk density, plant available water and water content at pF 2.54 and pF 4.2. Soil quality value calculations obtained with least squares linear regression for three different ages of oil palm plants, did not show significant effect on soil quality of Andisols under small oil palm plantation in West Pasaman district. Our findings suggested that there was no effect of oil palm ages on soil quality of Andisols, however other researches in soil biology and biochemical properties are still needed to obtain a comprehensive result.