Note: If your sensor does not give you usable readings even after it has been buried for a week or so, you may need to adjust it. To adjust this sensor, you can change the value of the resistor. When you have some chart data so you can see the behavior of the sensor, you will be able to see if it is drifting nicely in the middle somewhere, or if it is peaking out (hitting the top or bottom of the graph - which means you are loosing data). By changing the value of the resistor, you can adjust the operating range for this sensor so that all your data shows up in the middle of the graph somewhere.