Zone Settings for Subsurface Drip Tubing

A little deeper searching found this:

and this:


(online calculator link does not work)

If my math is correct:
.61 GPH = 0.01017 GPM (from https://www.convert-me.com/en/convert/flow_rate_volume/gallon_hour.html?u=gallon%2Fhour&v=0.61)

PR = (96.25(A * B)) / C

1.098082692307692 = (96.25(175 * 0.01017)) / 156

Basically, my PR = 1.1

What is PR? Is this Nozzle Inches Per Hour?

I think I have my head around Allowed Depletion and Efficiency. My SDI should be very efficient.

I’m using 50% Allowed Depletion and 90% Efficiency.

What do I use for “Crop Coefficient”? I selected “Cool Season Grass” for my vegetation type (70% Perennial Ryegrass and 30% Fine Fescue). It looks like the software defaulted to 80. This page


says 70. This thread Crop Coefficients and @franz indicates it is different every month and to use an average. The average of @franz’s values is 78.3 year round and 88.6 April - Sept. Should i Use 70, 78, 80, or 89?

Outstanding, I would like to figure out what value to use for “Available Water” (I understand what this is, how do I calculate it and what units is it?), “Root Depth” (How is this affected by subsurface drip; effectively at the root?), and “Nozzle Inches Per Hour” (Is this the PR value above?).

Thanks again.