DETERMINATION OF SOIL INFILTRATION RATES ON MALETE SOIL USING THREE EXISTING INFILTRATION MODELS.

Abstract The determination of soil infiltration rates is essential for effective water management, irrigation planning, and erosion control in agricultural systems. This study assessed the infiltration characteristics of Malete soils using three existing infiltration models: Horton, Philip, and Kostiakov. Field infiltration data were collected and analyzed to evaluate model performance across different soil textures. Results showed that the Horton model effectively described infiltration behavior in loamy soils, capturing the rapid initial infiltration rate and gradual decline to a moderate steady-state rate. The observed initial infiltration rate for loam was 82.5 mm/hr, decreasing to a steady rate of 12.3 mm/hr, with a coefficient of determination (R² = 0.91) and root mean square error (RMSE = 2.8 mm/hr). In contrast, the Philip model provided the best fit for clay soils, where high initial sorptivity (S = 18.6 mm·hr⁻¹/²) was followed by a very low long-term infiltration rate (0.9 mm/hr). The model achieved a higher accuracy with R² = 0.95 and a lower RMSE (1.7 mm/hr) compared to Horton’s performance on the same soil type (R² = 0.83; RMSE = 4.5 mm/hr). This reflects the slow permeability and higher susceptibility to runoff in fine-textured soils. The Kostiakov model gave useful empirical predictions of cumulative infiltration across soil types, complementing the mechanistic approaches of the other two models. The comparative evaluation highlights the influence of soil texture on infiltration dynamics and demonstrates that infiltration models can serve as valuable tools for designing site-specific irrigation systems in Malete. The findings have significant implications for water management, emphasizing the need for irrigation practices that align with the infiltration capacity of each soil type to reduce water losses, minimize erosion risk, and improve water-use efficiency. Overall, the study provides a scientific basis for sustainable irrigation scheduling and soil conservation strategies in Malete, contributing to improved agricultural productivity and environmental protection in the region.