Influence of pedological characteristics and land-use types on soil erodibility and surface runoff in Pared sub-watershed, Alcala, Cagayan, Philippines

The study determined the influence of pedological characteristics and land use types on soil erodibility and surface runoff in Pared sub-watershed in Alcala, Cagayan. It specifically characterized the pedological features and major land-use types in the arca and established variability of soil erodibility and surface runoff relative to the land-use types which included corn field (CF), rice field (RF), forest land (FL), and grassland (GL). Water (aggregate stability) and wind (erodible fraction, dust emission potential and soil erodibility) erosion indicators were assessed through the dry sieving method. The relationships of soil properties and soil erosion indicators were identified. The potential surface runoff was also determined in each land-use type using the generated hydraulic functions from the soils in the area and through a model produced from Vensim software. The on-site cost of soil erosion was estimated using the replacement cost approach. The pedological features (morphological and physico-chemical properties) of cach of the land-use types indicated that these sites were prone to soil erosion. Based on soil erosion indicators, FL was the most resistant to erosion. Soil structure, soil texture and organic matter (OM) were also noted to directly influence soil erosion indicators such as aggregate stability index (ASI), and soil erodibility (K). The highest erosion rate (51.04 t/ha/year), however, was noted in RF. In general, the erosion rate regardless of land-use types reached 33.11 to 51.04 t/ha/year which was way above the tolerable soil loss of 3 to 10 t/ha/year. Moreover, the highest potential surface runoff (7.33 mm) was noted in GL, which was also higher than the usual documented runoff of 5.0 mm. The cost of replacing nutrient losses in PhP/ha/year due to erosion amounted to 50,347.93 for CF. 15,260.85 for RF, 50,888.68 for FL, and 13,399.08 for GL. The results of the study can be used by farmers, local government units, and other stakeholders to set priority locations for erosion control measures to prevent vast flooding similar to what happened in Alcala, Cagayan in 2019.