Probes Calibration Dr. Jeffrey Walker THE UNIVERSITY OF MELBOURNE Dept. of Civil and Environmental Engineering Daniele Biasioni

Field Calibration (tools and method) HydraProbe equipmentSoil sampling

Hydra values (V/V)% Water content (V/V)% HydraProbe Field calibration ThetaProbe Theta values (mV) Water content (V/V)% Rmse = 9,75 %Rmse = 9,70%

Field calibration per team Hydra values (V/V)% Water content (V/V)% HydraProbe Water content (V/V)% Theta values (mV) ThetaProbe

Field calibration per farm Hydra values (V/V)% Water content (V/V)% HydraProbe Theta values (mV) Water content (V/V)% ThetaProbe

Laboratory Calibration Preliminary preparation of soil sampleAdding water

Laboratory Calibration Putting the samples in oven Theta Probe testing Hydra Probe testing

Laboratory Calibration Weighing of the sample

HydraProbe (farm calibration) HydraProbe (general calibration) Lab calibration T=45º Hydra values (V/V)% Water content (V/V)% Sandy soil farms: Roscommon Cullingral Clayey-soil farms: Stanley Merriwa Park Illogan Midlothian Pembroke Dales Rmse = 8.9% Rmse = 8.2%

Lab calibration T=45º Theta values (mV) Water content (V/V)% ThetaProbe

Hydra values (V/V)% Water content (V/V)% HydraProbe Calibration relationships Sandy Soil Clayey Soil Theta values (mV) Water content (V/V)% ThetaProbe Field calibration trend line

Conclusions Field calibration of the Hydra probe and the Theta probe was unsatisfactory, due to various errors in the sampling procedure HydraProbe is highly sensible to the type of soil ThetaProbe is more stable at extreme values Further work will include the evaluation of the temperature effect on the response of the probes

Common errors in NAFE ’05 and possible improvements for NAFE ‘06 Doing 4 measurements around the cylinder and taking the average value Specific vegetation and soil sampling team different sampling equipment Sticking the probe too far from the soil sample Losing soil in the procedure of pushing it out from the cylinder (clayey soil), or extracting it from the ground (sandy soil) Bad soil sample labelling on plastic bags or/and on HydraProbe Swapping of soil sample ID in the drying procedure SAMPLE PROBE Errors Improvements