# Watering Theory



## mwemaxxowner (May 30, 2020)

Alright, so there are a few assumptions that have to be made, but I have something I've been pondering.

I know that we have to put down X amount of water, regardless of our nozzle sizes and flow rates, etc. The goal is to get down a certain amount of water. Run longer or shorter depending on factors but to achieve that amount of water.

I'm curious if it's better to run smaller nozzles putting out a slower flow, and run the system longer to achieve the proper amount of precipitation, if it's best to run larger nozzles for a shorter time span, or if it's just a wash.

This is assuming that, with the small nozzle scenario, we're still at (at least) the minimum recommended flow rate for the arc the sprinkler is set to that stryker recommends. Assuming that we're not SO small that we're finely atomizing the water and it gets blown away. Also assuming we aren't watering in the heat of the day where evaporation will be more of a factor.

In the larger nozzle scenario, assuming we have the flow rates to provide for the total flow and we're not overdoing it. Also assuming that we are not putting down SO MUCH water that we have runoff.

As I consider it I'm thinking that it might be best to go smaller but run the system longer. I am guessing that this could potentially help deal with any distribution issues that might be present because the heads would pass over the areas many more times. And maybe a slow distribution of water allows it to sleep into the ground better?

Just curious, and thinking out loud I guess.


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## gm560 (Feb 22, 2018)

This is basically the theory behind the lower precipitation rates of the Hunter MP Rotators. Water too fast can lead to run off and therefore a waste of water. Slower allows it to soak into the soil. Also the sprinkler controller I have has a cycle and soak feature, where it would water for X minutes and then break for Y minutes to let it penetrate before resuming again. The usefulness of these things would depend heavily on your soil, I would think.


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## mwemaxxowner (May 30, 2020)

I have very sandy soil. For me, I think runoff would be less of an issue.


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## ionicatoms (Mar 8, 2020)

Interesting question. I would think you'd target your soil's infiltration rate to minimize evaporation, minimize the duration of tissue wetness, and to (potentially?) carry treatments deeper into the soil. These are all just guesses. Interested to learn more.


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## ABC123 (Jul 14, 2017)

mwemaxxowner said:


> I have very sandy soil. For me, I think runoff would be less of an issue.


It all depends if its hydrophobic or not, any soil can repel water.

And with sandy soil anything over .38in is kinda wasted because it goes past the root zone and can only hold so much water.


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## mwemaxxowner (May 30, 2020)

I never have any mud or standing water.

But, aside from those observations, how do I determine "hydrophobidity" &#128514;?


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## g-man (Jun 15, 2017)

@mwemaxxowner check the ET and irrigation guide


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## Wiley (Dec 2, 2019)

Fun thread with a lot of variables in play. If you go down the ET (evapotranspiration) rabbit hole you can never go back!


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## mwemaxxowner (May 30, 2020)

I enjoy mulling things like this over &#128514;

I don't have much choice, I only have 8.5 gpm available at the meter. Maybe I'm just trying to make myself feel better about having to run smaller nozzles &#129318;&#127996;‍♂.

On a serious note, though, I'm a little curious about this so that, if they ever update our utilities around here and I get more flow available to me, if I would want to try increasing nozzle sizes or just leave it alone.


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## dleonard11122 (Jun 24, 2020)

As someone who irrigates from a well, I have to match the well pump's output to my irrigation systems output to avoid short cycling or pressure loss. This leads to me dumping ~ 20-22 GPM out of 4 heads across most of my zones, which average 4k sqft to 7k sqft. My precipitation rates are between .3"/hr and .5"/hr. Because of this, I imagine I am at the far upper end of "run larger nozzles for a shorter time span."

I do rely on my Rachio controller to cycle/soak whenever necessary to avoid runoff. Our yard is slightly sloped, and I haven't noticed any runoff/puddling.


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## mwemaxxowner (May 30, 2020)

ionicatoms said:


> Interesting question. I would think you'd target your soil's infiltration rate to minimize evaporation, minimize the duration of tissue wetness, and to (potentially?) carry treatments deeper into the soil. These are all just guesses. Interested to learn more.


Somehow I missed your comment. That's interesting, and nothing I've thought of.

I still haven't looked at the guide linked above, maybe it'll instruct me more on figuring out the infiltration rate.


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## mwemaxxowner (May 30, 2020)

In case any of you are talented enough to tell anything from photos, here is my soil. It's wet right now. It's almost powdery when dry.

But, I'm also interested in how this applies in general, not just for me.


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## ionicatoms (Mar 8, 2020)

Soil looks similar to some areas in my yard. See https://thelawnforum.com/viewtopic.php?p=310195#p310195 for information about humic amendments to sandy soil. Apparently it is a contentious topic.


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