To get my plot Moisture I am doing the following:
1). Get The Soil Sensor Tool
2). Move To first location
a). This is the first set/group of plants nearest Home (0,0,0).
b). I picked a point in the middle of a group of 4 plants.
3). Move Absolute - Just Z - lowered until soil sensor is in dirt to just below the gold plated sensors.
4). Wait 3 seconds
5). Read sensor
6). Move Absolute - 200mm up on Z only
7). Move Absolute - +10mm on X & Y
8). Back down and read again
9). Back up
10). Move Absolute - -20 on X & Y
11). Back down and read again
12). On to next location & repeat
I picked locations every meter to give me and overall view.