Morphophysical and Nutrient Characteristics of Degraded Soils in Sta. Rita, Samar, Philippines

Abstract

The productivity of degraded soils greatly depends on a good understanding of their characteristics. Hence, the study was conducted to determine the morphological, physical and chemical characteristics of degraded soils in Sta. Rita, Samar, Philippines. Four representative soil profiles located in different physiographic positions were examined, characterized and sampled. The examination was conducted using a pit measuring approximately 1-m wide and 1-m depth. Soil samples were collected from each horizon, processed and subjected to field and laboratory analyses. Results showed that the soils were derived from sedimentary rocks (i.e., shale). Well-developed soils were found on the summit and foot slope position (horizon sequence: Ap-Bt-BC-C), while moderately developed soils were obtained in the middle slope position (horizon sequence: Ah-Bt-C). Soils had a clayey texture with moderate bulk density, porosity and water holding capacity. They were friable to firm when moist, but plastic and sticky when wet. The soils were highly acidic (soil pH close to 5.0). They had a moderate amount of organic matter, low total nitrogen (N) and low available phosphorus (P); all of which had decreased amounts with soil depth. Exchangeable bases (calcium, magnesium, potassium and sodium) were high in most soil profiles. Thus, N and P fertilization and organic matter addition are highly recommended to increase the productivity of these degraded soils. Moreover, the soils were classified as Typic Hapludalfs or Haplic Luvisols because of their development degree. They were mature with the presence of an argillic horizon (B horizon with high clay accumulation) and high base saturation.