A few corrections for the technical crowd:
This technology hasn't existed since the 1800's. It is derived from a technology called Surface Renewal that measures the turbulent transport of mass and energy from the planetary surface to the atmosphere. The concepts behind Surface Renewal were first developed in the 1930s by chemical engineers. These chemical engineers developed a model to describe the movement of gases into liquid media by fluid volumes interacting with the air-liquid interface. In the 1990s, UC Davis researchers adapted the Surface Renewal concept to the planetary surface-to-atmosphere interface. Recent improvements in the technology enable Tule to measure the amount of water vapor carried away from crop field by wind eddies.
Our technology was validated for accuracy against the gold standard research tools used in academia, lysimetry and eddy covariance.
What truly makes our technology exciting is that we can tell farmers the optimal amount of water to apply to maximize plant growth (yield) and plant stress (quality). Studies have shown that getting irrigation right can radically change yield and quality. Before our technology, farmers have never had the feedback to optimize irrigation. This is analogous to NewRelic locating the bottlenecks in your server performance. You can't optimize until you can measure.
edit:
As requested, here are links to the technology:
An easy to read summary is here:
http://edu-tuletechnologies-com.s3.amazonaws.com/Tule_Surfac...
The original academic paper is here: