EVALUATION OF TDR MULTI-WIRE PROBE IN THE DETERMINATION OF THE DRIP IRRIGATION WETTING FRONT

The adequate estimation of the wetted front dimensions is fundamental to define the number and location of emitters in drip irrigated plants. Measurements of these dimensions are usually made using open trenches under the drip positions. Another method used is to monitor the soil water content variation along the soil profile with sensors. This works studies the use of TDR probes (Time Domain Reflectometry) with electrical impedance discontinuities to determine the wetting front in drip irrigation. It was analyzed multi-wire probes performances with two constructive materials: brass and stainless steel. The developed probe has 4 rods with 0.675 m of length and was divided in 4 segments. The tests were conducted in a 200 L bucket, where the dynamic of water process was monitored during 48 h, after a drip application of 5 mm of water. The experiment was realized with Red Oxisol soil type with an average bulk density of 1.200 kg/m³. The results showed the viability to estimate the wetting front using TDR equipment coupled the brass multi-wire probes with electrical impedance discontinuities.

SOUZA, C. F.; MATSURA, E. E.; TESTEZLAF, R.  
UNICAMP/Feagri – Departamento de Água e Solo
Brazil