Development of pedotransfer functions to predict water-stable aggregates in heated and unheated soils

A b s t r a c t.The wildfire temperature can affect many soil properties, such as aggregate stability.The water stable aggregate (WSA) is a soil property not typically considered in soil analysis, so pedotransfer functions are an alternative for estimating it.This study provides a series of pedotransfer functions as models to predict the effect of heating on WSA using basic soil data.Soil samples were collected from 22 different sites and analyzed in the laboratory before and after being heated at 100 and 300°C.These temperatures represent low-and medium-severity wildfires.Bulk density, organic matter (OM), sand, silt, and clay contents, and pH were used to estimate WSA for unheated and heated soils.The results showed no significant differences in WSA between unheated soils and those heated at 100°C but a significant decrease at 300°C.WSA correlated significantly with OM content and pH in unheated soils and 100°C heated soils (p<0.01),but not at 300°C.A non-linear model was developed to predict WSA in unheated soils, and two additional models were developed for heated soils.Finally, at 300°C, the organic matter, clay content, and water-stable aggregates decreased significantly while pH increased.