The increase of fertigation techniques has not been followed by researches that generate available information to guide a correct fertigation management. The time-domain reflectometry allows the simultaneously monitoring of soil water content (theta) and bulk electrical conductivity (CEa). Literature presents various models which relate TDR readings of theta and CEa to soil solution electrical conductivity (CEw). Nevertheless, many researches demonstrate the need for evaluation and calibration of these models under different soil conditions. In this work, six mathematical models were evaluated in order to establish the relationship among theta, CEa e CEw. Laboratory experiments were carried out using two soil materials, by means of applying five electrical conductivities combined with five soil water contents in PVC columns. The models allowed a reasonable relationship among theta, CEa e CEw with better performance of de RHOADES et al. (1976) e de VOGELER et al. (1996) models for the soils 1 and 2, respectively.
TDR; mathematical models; fertigation management
