Paper Title
Evaluation of Pedotransfer Functions for Estimating Soil Moisture Constants: A Study on Soils in Dry Zone of Tropical Sri Lanka

Abstract
Soil hydraulic parameters often play a key role in resource planning and management in agriculture and environment. Hence, lack of reliable data on soil hydraulic parameters is one of the major drawbacks in resource planning in tropical countries. Pedotransfer functions (PTF) can play a significant role in filling this data gap. Therefore, this study aimed to evaluate the existing PTF developed for tropical soils to identify the potential use for dry zone soils of Sri Lanka. Twenty two PTF developed by 9 research works were selected to find out the applicability of PTF to predict volumetric water content (VWC) at -10, -33 and -1500 kPa for tropical soils in dry zone Sri Lanka. Further this study aimed to identify the potential predictors to develop PTF for dry zone soils of tropical Sri Lanka. Out of the selected 22 PTF, three PTF developed by Botula et al. (2013) showed better performances compared to other PTF. Sand and bulk density were identified as the probable predictors to predict VWC at -10 and -33 kPa while Clay was identified as a probable predictor to predict VWC at -1500 kPa. Keywords - Pedotransfer functions, Sri Lanka, tropical soils, volumetric water content.