The CS511-L is a galvanic dissolved-oxygen probe that is designed to work in water. As O2 passes through the semipermeable membrane, the oxygen reacts with the electrolyte solution in the probe. As more oxygen becomes available, an electro-chemical process occurs, so that an increase in the mV output is recorded. The source of the oxygen can be through the air, water, or a liquid slurry. Soil is not very homogeneous, so the dissolved oxygen is not able to move freely.