Hello all, we’ve just released a new feature we call Dynamic Crop Coefficient, and we’re excited to already see interest in the feature. We build this in part using feedback from the community in these forums, so I’m posting this here as a starting point to get more feedback from the feature as customers use it.
We’ve written up an FAQ document that will address many of your questions, here: Dynamic Crop Coefficient FAQ
Beyond the FAQ, I’ll take some time here as to address specific questions that have come up in the community.
In a nutshell, this feature generates a new crop coefficient (Kc) value every month for all crops, for every zone. When you turn the feature on, you’ll get that value for your zone and cannot edit the value. You can toggle the feature on and off as much as you like. The values are local to your climate, and will change every month.
Our hope is that this feature will help avoid the heat-stress problems that many customers experience in peak summer. If you think about a sinusoidal curve vs a flat line, it’s clear that the static Kc values we used to provide were really only accurate some time in Fall and Spring, and were likely leading to over-watering in the shoulder seasons and under-watering in summer for a lot of controllers (they did for my yard).
The Kc values for turfgrass are regional, varying by high-level climate types, for example a mediterranean climate on the west coast will have different values that steppe/ semi arid climates in the Rockies, southwestern deserts, eastern humid regions, etc. I’m sorry I can’t be any more specific at this time.
The Kc values for garden-type crops will vary slightly across even smaller climate micro-regions, roughly the size of western counties. This is because we fit expected growing season Kc values to the local growing season timing, and we can do this at a finer spatial resolution.
Data sources: we compiled the Kc curves for turfgrass from peer-reviewed research where available and other academic published documents (Master’s theses, Ag school department materials, etc) where needed. For other crop types, like vegetable and flower gardens, we’ve taken average seasonal values from the U.N. Food and Agricultural Organization (FAO) tables, which are extensive, and fit them to the local growing season (link to FAO tables is in the support document).
You have already provided some great concepts for improving this feature. To get this to market quickly we did not build an offset or an enter-your-own function, and those are good ideas. If you want to apply an offset this season, you can activate the feature on the first of the month, note the value, turn the feature off, and set the value with whatever offset you want. I realize that is a hack, and we really want to learn about the appetite for a feature like this so we can plan follow-up features.
You have also identified other changes made the user interface. We combined the ‘Annuals’ and ‘Perennials’ classes into a ‘Flower beds’ class. It turns out a lot of customers didn’t know what those really meant, and even for those that do, our garden aesthetics often combine them. The root zone depth and Kc parameters for this new class is close to the average of the old classes, erring a bit on the side of more frequent watering. We have also made under-the-hood changes to “vegetable garden”, which will water more frequently, and changed “xeriscape” to “desert-adapted”, which will water less frequently and is a great choice for native steppe and desert plants that are becoming popular landscape elements in the southwest. In addition, if you set up new zones, you will find a cleaner and more informative zone setup process that we hope will lead customers to get it right more often the first time.
It’s worth saying that some of you have a really good intuitive and data-driven handle on how to tune a Rachio controller to get optimal results on your yard. We designed this feature as a finely discretized, yet generalizable solution that will work for most yards, most of the time. It could be that what you’ve learned through research and trial and error works better for your yard, and if so, keep doing what you’re doing! And please let us know if when you find discrepancies; we’re committed to improving this feature and we want your feedback.