Calibrating Soil Watch 10 Sensor and accuracy of the readings

[pinolec]

Hi,

The math provided for calculating VWC does not need the volume of soil, so the math applies for all types of soil, and the maximum VWC could be assumed at 45%, correct me if I'm wrong.

This is correct.

So also the voltage feeding to the  soil watch also gets varied and also there is a variation in readings we observed,

The issue is within ADC. SoilWatch 10 gives same results regardless of supply voltage.

The easiest solution is to use ADC with a constant reference voltage. Many microcontrollers have the option to use an internal reference voltage. For eg Arduino Uno have an option of internal reference voltage 1.1V but also you can supply external reference voltage. Other microcontrollers / ADC may offer different internal reference voltages and/or option to connect external reference.

Using LDO to run microcontroller is a waste of power. But some LDO's may be used as an external reference voltage for ADC (Turned on for measurement only).

Regards,
Piotr

[aylashiv]

Hi,

what is the Operating Temperature of this Soil watch 10 sensor? As it was not clear in the website.

[pinolec]

Hi,

The operating temperature is 2-45 degree C. Outside this range the sensor may be less accurate and probably its lifespan will shorten. You should not exceed the range of -20 to 80 degree C as this may instantly damage the sensor.

Regards,
Piotr

[aylashiv]

" And use formula where y will be your aproximated VWC:
Code: [Select]
y = 15.5x + 2.58

That way you will have no problem with values over 100% "

Can  i know can we use this math in our programs to find out the VWC of the soil, any updates can you specify.

[pinolec]

Hi,

Yes, you can use it estimate VWC. It is not the most accurate estimation at the very dry or the very wet ends of the range. We don't have better conversion formulas at this time.
See this topic: https://pino-tech.eu/forum/soilwatch-10/sensor-in-hand-21/ it looks like someone is going to make the calibration a lot better.

Regards,
Piotr

[Kalliandra]

Hi Aylashiv,

I suggest to you calibrate the soil with the readings of the sensor. In my topic that pinolec point i use a methodology that i see is very good and accurate.

I work with irrigation management here in Brasil and I'm liking this sensor.

regards,
Gabriel

[aylashiv]

Kalliandra,

Thanks for the reply, I was bit late in replying to the post.

The Issue is, how do I correlate the Soil-moisture of a sample volume with the Field?
My application has a large Hectare farm of 100Ha,  I have to measure the VWC% of that Feild, and evaluate the readings. how shall we calculate the VWC of such a large field?
Any methods, can you share your approach with us like how you have measured the soil VWC from the Soil watch 10 ?

[aylashiv]

Hi,

Yes, you can use it estimate VWC. It is not the most accurate estimation at the very dry or the very wet ends of the range. We don't have better conversion formulas at this time.
See this topic: https://pino-tech.eu/forum/soilwatch-10/sensor-in-hand-21/ it looks like someone is going to make the calibration a lot better.

Regards,
Piotr

Thanks Pinolec for the reply, As you mentioned that water percentage cannot exceed 42.5% in any sample taken, So, 42.5% is the maximum water holding capacity of any type of soil?

And  What is the Volumetric area of influence of this Soil watch 10 sensor? In how much volume we could say that it affects the moisture readings.

[pinolec]

Hi,

Most of the mineral soils will not exceed 42.5% VWC. High clay content soils may exceed this value and we recommend doing s soil-specific calibration. The volume of influence is small we don't know the exact measurement. We know that most influences on the reading have the soil in contact with the sensor.

regards,
Piotr

[aylashiv]

Hi Pinotech,

Can you share the Schematic of the Soil Watch, To understand the Process,Internally, Just for my educational Thesis I need to submit the paper.

[pinolec]

Hi Pinotech,

Can you share the Schematic of the Soil Watch, To understand the Process,Internally, Just for my educational Thesis I need to submit the paper.

Sorry, but we don't share our schematics.