Characteristics of soils derived from ultramafic rocks in Homonhon Island, Philippines

photo0091Miguel Francisco B. Abulencia and Faustino P. Villamayor, 2013 *( 


The prevalence of mining activities in Homonhon Island, Philippines has affected the soil resources and the agricultural livelihood of the people in the island. Thus, this study aims to determine the physical and chemical properties of the soils and recommend suitable tree species for revegetating the area.

Five pits representing specific positions in the hillslope (i.e., summit, shoulder, backslope, footslope, and toeslope) were selected and representative soil samples from each horizon of the pit were collected for analyses following standard procedures.

Soils have pH values ranging from 5.5 – 6.8 and low potential CEC values of <34 cmol(+)/kg with the presence of kandic horizon in all soils except for the backslope which has cambic horizon. Moreover, soils generally have decreasing organic matter content and available P with increasing depth. All the soils except for the backslope are classified as Kandiudults while the backslope qualified as a Dystrudept.

Acid-tolerant species such as Piliostigma malabaricum is suitable in the area. Morover, no-tillage and or contour hedgerow can be applied in the hillslope so as to minimize soil erosion. Addition of organic materials through green manuring is beneficial as it does not only promote aggregation but also serve as a source for nutrients.

keywords: ultramafic rocks, mining activities, Piliostigma malabarcium