Avaliação da umidade do solo por meio da técnica da tdr sob influência de diferentes concentrações de hidrogel.

Abstract

Soil moisture can be measured by some techniques. Among of them, the TDR (Time Domain Reflectometry) usually shows good results. Hydrogels can modify soil properties, contributing to improve soil water storage capacity, that is why they are been used on the last years on agriculture. However, recent studies showed that soil properties can affected TDR readings. Four substract composed by sand and different concentrations of hydrogel were mounted to evaluated its effects on readings of TDR. To compare TDR readings with substract moisture (q), it was gravimetrically measure. The results of moisture readings were submitted on statistical analysis. Could be observed that different concentration of hydrogel caused little influence on the readings of moisture using TDR. The models that related q with dielectric constant (Ka) showed high values of determination coefficient (r2 > 0.993), for all concentrations. Statistical analysis of fitted models parameters show significant differences among them. But, in practical view point we can accept that these differences are little enough to be negligible in relation to TDR reading variations. These variations are caused by some variables like: probe characteristics, substract-rods contact and others that affect TDR reading.