Soil Water Content Estimation using Pedotransfer Functions in Drylands of Sumbawa Regency

Abstract The research aims to estimate soil moisture content using pedotransfer functions in drylands of Sumbawa Regency from March to July 2019. The research method used is descriptive-comparative design against the soils’ physical properties in three different locations. Soil sampling is conducted through undisturbed soil sampling using sample rings for soil analysis and file input assembly and simulation using the Soil, Plant, Atmosphere, Water Field and Pond Hydrology Model (SPAW) program of Version 6.02.75. The soil sample analysis for soil physical properties is conducted at the Soil Physics Laboratory of Soil Department, Faculty of Agriculture, Brawijaya University, Malang. The analysis results indicate that soil moisture characteristic values using PTFs method with minimum parameter inputs that include soil texture (sand and clay) and organic matter could be implemented in drylands. There are differences in the available moisture content between measurement at the laboratory and simulation. The available moisture values from the field result measured at the laboratory are far smaller than those of the simulation results. The values indicate a variation of 0.31-0.47 cm3/cm3(KL) and 0.05-0.32 cm3/cm3(TLP), AWC (0.11-0.17 cm3/cm3), and hydraulic conductivity (soil permeability) (0.19-6.45mm/hr) for all locations.