Tule (YC S14) Is a Crop-Hydration Sensor for the Tech-Savvy Farmer | Hacker News Reader

Tule (YC S14) Is a Crop-Hydration Sensor for the Tech-Savvy Farmer

techcrunch.com

29 pointsjefflab10 comments

I'm a cofounder of Tule and happy to answer any questions.

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:

http://myweb.ecu.edu/suh/PawU1995.pdf

That wasn't at all the sort of technique I was expecting. Without knowing otherwise, I'd presumed that you were doing something that directly measured evaporation rate, and that the claim that it was covering a large area instead of a single point was just puffery based on the the hope that air conditions were constant over the whole area. This is much better.

I only glanced at the original paper, but I was lost by the end of the first sentence: "Numerous methods exist for estimating the flux density of scalars." Mathematically, that doesn't make much sense. Does scalar have a different definition in meteorology? Or is this an odd translation from another language?

Obviously I am unaccustomed to the waters of Hacker News. I meant to post this in response to nkurz's question rather than the main thread. See below.

Hi, I'm Tom, the other cofounder at Tule. I developed the recent improvements in Surface Renewal during my PhD work at UC Davis.

Examples of scalars, as the term is used in atmospheric science, are air temperature, water vapor concentration, carbon dioxide concentration, or any other constituent of the atmosphere.

Here is a more formal definition from http://glossary.ametsoc.org/wiki/Scalar:

Any physical quantity with a field that can be described by a single numerical value at each point in space. A scalar quantity is distinguished from a vector quantity by the fact that a scalar quantity possesses only magnitude, whereas a vector quantity possesses both magnitude and direction. Thus, pressure is a scalar quantity and velocity is a vector quantity.

Neat stuff! I don't know much about how your sensor communicates... wifi or cell maybe. But if you happen to be using 915MHz ISM band for anything we make a little $99 MFi accessory for iOS designed for drones you might be interested in playing with. Feel free to ping me.

Neat stuff. It's a sensor that measures actual evapotranspiration in the field, which is essentially how fast the leaves are losing water. This can be very useful in deciding how much irrigation is needed so that the plants are not unduly water stressed. The link to their website in the article turns out to be broken, but it leads to https://www.tuletechnologies.com/.

There were a number of interesting things in their FAQ that weren't mentioned in the article. The main one that jumped out is that contrary to the article, the cost is not $1500 per sensor, but is a $1500 per season subscription, with the use of the sensor being included. That's an interesting model. And I greatly admire that they are being so clear about pricing on their site.

Also from the FAQ:

  How do we know it works?

  We use a recent innovation in atmospheric science from the 
  University of California at Davis to measure Actual ET. 
  This innovation was validated against lysimetry and eddy 
  covariance. From a technical perspective, Tule uses the 
  Surface Renewal method to measure how much water vapor the 
  wind is carrying away from the field. If you’d like a more 
  in depth look at the technology, please let us know.

Yes, I'd like to know. Perhaps some details or links could be posted here?

Thanks for the kind words! Links posted above.

Hi, I'm Tom, the other cofounder at Tule. I developed the recent improvements in Surface Renewal during my PhD work at UC Davis.

Examples of scalars, as the term is used in atmospheric science, are air temperature, water vapor concentration, carbon dioxide concentration, or any other constituent of the atmosphere.

Here is a more formal definition from http://glossary.ametsoc.org/wiki/Scalar:

Any physical quantity with a field that can be described by a single numerical value at each point in space.

A scalar quantity is distinguished from a vector quantity by the fact that a scalar quantity possesses only magnitude, whereas a vector quantity possesses both magnitude and direction. Thus, pressure is a scalar quantity and velocity is a vector quantity.

The soil moisture probe comment in the article is wrong. Several years ago I worked for an agricultural telemetry company, and we resold soil moisture probes that were several meters in length - measuring far more than 'a few cubic inches'. The soil moisture probes were excellent for determining when the plants were finished 'drinking', and you could also use them to determine how far down the roots reached.

It's interesting to see the chickenwire around the probe, too. We had a problem with native parrots who ate everything; our weather stations had rubberised doppler probes... eaten; plastic cable ties... eaten; anything not metal... eaten. Probably not digested, it's just that the birds get bored and try anything...

In the sign up form you list a few crops (Almonds, Grapes, Carrots, Tomatoes, Walnuts). I'm surprised to not see the big dollar US crops on the list (corn, soybean, wheat, cotton). Do the same principals apply to those crops as well?

The technology definitely applies to the big dollar crops (corn, soybean, etc), and we plan to serve those markets someday. We are starting in specialty crops (almonds, grapes, tomatoes, etc) because these customers have a "hair on fire" problem with intensive irrigation management and the California draught.

Reply on news.ycombinator.com