soil moisture measuring

Let's Go!

I am considering measuring the soil moisture for my garden using the vegetronics sensor. It appears this gives a signal from 0 to 3 volts, depending on the moisture level. Can anyone give me an idea how to program this into the bs2 and then give an output.

Thanks,

Jim

Franklin

Check out RCTIME or use an ADC chip.

Borsodi

I am also using a bs2 stamp to measure soil moisture and light, heat, soil properties. I am trying to interface Vernier test instruments or lego NXT sensors. Have you had any success?

best

al

Tracy Allen

Definitely use an ADC with the Vegetronix sensor, to read its output of 0V–3V. Once the Stamp has the voltage, it can use the curves supplied by Vegetronix for your particular model to convert the voltage to VWC (volumetric water content). They recommend a 10-point interpolation. From there it may be possible to convert VWC to soil suction pressure in kPa, which is a measure of work that plants have to do to extract water. It depends critically on the type of soil, as clay types hold onto their water much tighter than do sandy types.

Ultimately it will come down to observing onset of stress in your plants and the point in voltage, VWC or kPa at which stress occurs. Trigger irrigation before it reaches that point, given other inputs.

With any sensor of this type it is important to keep the sensor itself in intimate contact with the soil it is measuring. Voids significantly skew the measurement.