Kenneth Oraiz* and Victor B. Asio
The widespread occurrence of marginal uplands is a serious agricultural and ecological problem in the Philippines. The study evaluated the morphological and physico-chemical properties of soils in the marginal upland of Sta. Rita, Samar. Three soil profiles located at different physiographic positions were examined and sampled. Findings revealed that the marginal upland soils were derived from mudstone. They were characterized by an Ap-Bt-BC horizon sequence and they were clayey with moderate to high porosity and water holding capacity values. The soils were friable in their surface horizons when moist, but plastic and sticky when wet. The soils had pH(water) values ranging from 5.20 to 6.86, indicating that soil acidity was not yet a serious problem in these soils. The soils had moderate soil organic matter contents in their surface horizons but low amounts in subsurface horizons. Total N and available P of the soils were low and a problem for crop production. However, the soils had moderate to high exchangeable bases and cation exchange capacity values. In terms of degree of soil development, the marginal upland soils was observed to be mature as reflected by their horizonation, particularly by the presence of an argillic horizon (B horizon with high clay accumulation). But they still had high base saturation, suggestingthat they were not yet highly leached andthus, were classified asTypic Hapludalfs or Haplic Luvisols.
Keywords: marginal upland soils, mudstone, soil characteristics, Alfisols, Luvisols