Morpho-physical and Nutrient Properties of Soils in the Plantation Forest of Northwest Samar State University, San Jorge Campus (NwSSU-SJC), San Jorge Samar, Philippines

Understanding soil characteristics in plantation forests established on marginal lands is essential for evaluating productivity and ecological recovery. This study characterized the morpho-physical and nutrient properties of soils in the plantation forest of Northwest Samar State University-San Jorge Campus.

Four representative soil profiles along a slope gradient (summit, upper slope, middle slope, footslope) were examined through 1 m × 1 m soil pits. Morphological and physical properties were described following FAO guidelines. Horizon samples were analyzed for pH, organic matter (OM), total nitrogen (TN), available phosphorus (P) and exchangeable potassium (K).

Soils derived from shale exhibited varying development influenced by topography and vegetation. Summit and footslope profiles were moderately to well developed (Ah-Bw-BC or Ah-AB-Cr), while upper slope soils showed moderate development. Textures were predominantly clayey with moderate bulk density (1.30-1.45 g cm^-3) and porosity (45-51 %). Soils were moderately acidic (pH 5.0-6.2), with moderate surface OM (2.42-2.98%) and TN (0.15-0.24%), but low available P (1.83-2.24 mg kg^-1). Exchangeable K was relatively high in surface horizons (190-407 mg kg^-1). Nutrient concentrations declined with depth. Results indicate that plantation vegetation enhances organic inputs and structural development, promoting gradual soil recovery despite inherent acidity and low phosphorus. Continuous monitoring and nutrient-efficient enrichment planting are recommended to sustain long-term soil fertility and ecological resilience.