So far, using autonomous robots to make soil measurements is...

So far, using autonomous robots to make soil measurements is somewhat futuristic. In general, robotics for scouting still has many limitations, including providing them with enough power to operate efficiently for long periods. However, hypothetically, you could mount one of these recently developed sensors onto a robot and if smart enough, the robot could even decide by itself how far away to make the next measurement based on geo-statistical field data.