capacitive soil moisture sensor v1.2 temperature problem

Other Hardware Sensors
1

I measure soil moisture (v1.2) and even though it rains and rains a lot, the soil moisture keeps falling and falling. I also use DS18B20 to measure soil temperature. It can be seen from the graph that the humidity decreases with temperature and rain has no effect on this. I would expect to get 90% soil moisture when wet. Water stands everywhere.
Can you tell me what might happen to it?

#define pinSoil A7
const int AirValue = 620;
const int WaterValue = 355; 

Soillevel = analogRead(pinSoil);
SoilPercentage = map(Soillevel, AirValue, WaterValue, 0, 100);

meteograph.png
meteograph.png1200×550 14.1 KB

meteograph.png
meteograph.png1200×550 14.1 KB

2

I'm missing a link to the hardware you're actually using.

The AirValue and the WaterValue are two values you have to actually measure and then fill in the values in the sketch. You probably didn't do that so the values may be completely wrong for your hardware.

3

I obtained the values from completely dry soil and completely wet soil. I use arduino nano.

The point is that as soon as the temperature drops significantly in the soil, the humidity also drops even when it is raining outside.

The sensor is always off. Power is low. Only when measuring is power high and I will perform one measurement and again the sensor is power low. I measure every 30 minutes.

4

We still don't know which hardware you're actually using! Provide a link to the datasheet of that sensor!

The point is that as soon as the temperature drops significantly in the soil, the humidity also drops even when it is raining outside.

Depending on the used hardware that may be the standard behavior and you have to compensate for it in code or the sensor doesn't work. As we still have no clue what hardware you're using, we cannot help.

I obtained the values from completely dry soil and completely wet soil. I use arduino nano.

I have some doubts that you get exactly the same values as the example sketch has.