# Turf Hacker



## g-man (Jun 15, 2017)

In my random lawn search today, I stumbled on this blog. http://www.turfhacker.com/

I was looking for easy to maintain ET calculations and he shares a google doc for it.

His 02Mar2018 post about MLSN math is very easy to follow. The 22Feb post around fast growing grass has less dollar spot is also very interesting.

Enjoy.


----------



## osuturfman (Aug 12, 2017)

Jason is a wicked smart, down-to-Earth guy who has really challenged many of the dogmas related to turfgrass management. Happy reading!


----------



## g-man (Jun 15, 2017)

@osuturfman I've been reading more and more from him today and his Twitter feed.

I really liked his monitoring of clippings. I think it provides a close loop feedback. We are all a bit OCD with our inputs (fertilization, irrigation, etc), but not so much with the outputs. Control charting the clippings provides a quick way to measure the response.


----------



## Ridgerunner (May 16, 2017)

@g-man Glad you found and shared this. Thanks.
I investigated ET and growth potential a couple of years ago and got a bit overwhelmed, but you've pricked my interested again with this. I wonder what his source was for the nutrient ratios, I've seen others that don't match K and haven't seen any that addressed micros before. Thanks


----------



## g-man (Jun 15, 2017)

Ive been playing around with the tools he posted online. I really like the Ultimate Turfgrass Weather Modeler. It queries the forecast from WeatherUnderground and predicts the Growth Potential for your local weather. It then has charts for to show the historical. It does the same with ETo and a the new Dollar Spot Predictor. It is very easy to use. It runs on a google sheet script at night after you set it up. @Pete1313 I wonder how close it matches your manual ET tracking.



PS You do need to get your one WU API Key, but it is free. I already had one from moving data from WU to PWS.


----------



## Pete1313 (May 3, 2017)

@g-man, I've got my excel sheets all set up and ready to calculate! That stuff looks like it would put what I have to shame.. I'm going to have to check it out! :thumbsup:


----------



## g-man (Jun 15, 2017)

Jason updated his spreadsheets to use Dark Sky API. This was my plan for the winter update to the log file. It doesn't collect accurate precipitation data from your local station. This is the same problem I discovered with Aeris Weather API.

If someone wants to get GDD or other weather data, you could use his spreadsheet. My search for how to read individual precipitation data is still on.

http://www.turfhacker.com/p/jasons-productivity-file.html


----------



## TonyC (May 17, 2018)

I recently spent a few hours working through Jason's spreadsheet. If he wrote that code and crafted those equations, then I concur he's smart. There are techniques in that sheet that one might call Jedi like. The ET formulas alone are insane. Here's just one of them. I definitely need to crack a book to understand what is going on in there.


```
=0.0023*(((B13+17.8)*power((C13-D13),0.5)*(((((24*60)/pi())*0.082)*(1+0.033*cos(((2*pi())/365)*days360($B$6,A13+1))))*((acos(-tan((pi()/180)*$B$4)*tan((0.409*sin((((2*pi())/365)*days360($B$6,A13+1))-1.39)))))*sin((pi()/180)*$B$4)*sin((0.409*sin((((2*pi())/365)*days360($B$6,A13+1))-1.39)))+cos((pi()/180)*$B$4)*cos((0.409*sin((((2*pi())/365)*days360($B$6,A13+1))-1.39)))*sin(acos(-tan((pi()/180)*$B$4)*tan((0.409*sin((((2*pi())/365)*days360($B$6,A13+1))-1.39))))))*0.408)))*$B$5
```
I was surfing for info because I had already created a Google Sheets for Smith-Kerns Dollar Spot Probability since I had some fun fungal experiences last season. There are indeed some additional Gems in Jason Ultimate sheet, and I bow and give all credit to him. I merged several of my other sheets (Zoysia Calendar, Notes & ToDo's, and plan to link in some Forms like Jason does to populate data from the field (I mean front yard).



The json data parsing is not for the faint of heart, and I work with data in my real job. At first I was going to go with the Dark Sky (love their phone app), but like an earlier poster I have a WeatherUnderground API key so I was half setup. And WU (Weather Channel) is getting huge push back from the users. I enhanced some of the scripting to compensate for missing humidity (WU) data on rainy days, and expanded the date ranges. I've added some additional threshold lines to the charting to make things easier to consume visually. I would like to source in my Rachio watering data, but that would be a post processing step at this point.

If someone has a good publication that describes those ETo calculations I would really like to read it.

Cheers!

Tony


----------



## g-man (Jun 15, 2017)

Jason is the real deal. He updated the sheets to use DarkSky. I've based my log sheet on his approach and tweaked the script from it.

WU will shut down (now 15Feb), so make the move. I'm running both until WU shuts down.

Jason is very active in twitter and shares a lot of good turf info. https://mobile.twitter.com/pendersuper?lang=en


----------



## TonyC (May 17, 2018)

Well, Apple just blew up (bought) Dark Sky and it's API.

This will certainly impact sheets such as this and applications that rely on the Dark Sky API.

Apple Purchases Dark Sky Killing Android Apps and API


----------

