Avaliação de um TDR para determinação do conteúdo de água do solo.

Abstract

Of the several techniques used for the determination of the humidity of the soil, the technique of the time domain reflectometry(TDR) it is waking up plenty of interest, because it presents desirable characteristics, as the measure in real time and the possibility of automated readings. On the other hand, besides the high cost of the equipments, this method still presents calibration need. With the objective of evaluating the behavior of an equipment of TDR, using the tensiometer as reference method, an experiment was led, with the collection of values of the humidity of the soil and of the respective reading of TDR with three probes placed to three different depths tends a tensiometer for each probe, in a profile of located soil in vegetation house in the campus of UFCG in Campina Grande/PB. The tensiometer came as method of quite efficient reference for the measurements, because your methodology is very established and your operation doesn't influence nor it is influenced by TDR. The comparison curves showed great variability among the depths, for the answer pattern, expressed for the angular coefficient of the straight line and R and the percentile deviation. The fittings made starting from the data obtained by layer they exhibited dispersion of the values mainly in Monday and third layer as display the comparison equations. The results of this work come to complement other studies reported in the literature, showing that the application of this model of TDR is practically unviable without one foresaw calibration for each soil type, because the variations of the answer of very big healthy TDR.