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Automatic Cycle and Soak: How does it work?



  • Official comment
    Rolando Soto
    Hi Peter
    Your statement like "all zones have the same properties for clarity sake" is a completely hypothetical statement which never happens in real life. In this hypothetical case, yes - Your statement is right but it will never happen :)
    Let's try to elaborate for real life - neither the cycles, neither the maximum run time, neither the minimum soak time are the same for different zones so real life cycles will be something like 1,2,3,4,5,2,4,soak,4,soak. In many cases if the 1 is a drip and the 2 is rotor might worth switching them to let more soak time for the rotor zone ... And this will take us into the endless combinations world in case of 16 zones needing a supercomputer to get the best one which ends in the shortest time possible because that is important too :)
    To clear up some terms let's see what is cycle&soak: the main target is to eliminate the water loss due overrun. The soil together with the plant is like a sponge - if it is soaked completely the additional water will either stay on the surface creating puddles either will be lost in the drainage. The completely soaked state can be reached with irrigation for a given time which is usually called maximum run time and the time needed to this amount of water to soak in is called minimum soak time.
    Both values are usually between 5-30 minutes (depending on soil and plant type can go even up to a hour or more). But this soak times are minimum ones - agriculture experts are recommending to keep a hour between cycles soak time for grass. This has more reasons: 
    1. Many times users do not know their soil type or the soil is not the same type on the whole area. So experts are recommending values for clay (slow soak).
    2. The long soak time eliminates the risk of runoff and also healthier for the plant - for example in case of grass it pushes the grass the form longer roots which is better for the plant. A second feature what can be used to do deeper irrigations instead of shallow ones is the minimum watering time - the automatic cycle and soak will carry over shorter periods to the next day. Setting this minimum time to 3 minutes for example instead of irrigating 3 minute every day will irrigate 0,6,0,6,... in the spring when the evapotranspiration is not that big thus making the grass healthier (longer roots).
    As You can see the "minimum soak time" is not a trivial question, if we let 30 minutes+ for soak for every zone it won't matter that much if the next cycle will start immediately after the minimum soak time ends or a hour later since the evaporation will be around the same. 
    Also Your ModeB would create lot's of water loss if the cycles would be short but they are not. They are the maximum time possible without runoff - it's not like just watering the surface - it is a complete soaking of our "sponge". 
    Nevertheless Your point is right - we plan to make a deeper study into this direction which might end in a smarter distribution of cycles depending on irrigation type too and hope we can find a way to minimize this evaporation loss for rotors if we can. Remember that smart soak&cycle is working only inside a program, cycles between two programs are not mixed together so if You plan using this feature try to make as less programs as possible. 
    Thank You for the feedback! 
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    Hi Brown, 

    >agriculture experts are recommending to keep a hour between cycles soak time for grass. 

    This definitively is good for deep infiltration, but it disregards evaporation, maybe these rules were created when water scarcity was not a problem. 

    In my view, and especially with longer than usual soak times generated by long sequence of zones (example: more than 1,2,3,4,5,6,8 zones) creates the perfect evaporative environment.  I don't know how much water accumulates on grass above ground, but my guess is that the 1st 15-30 seconds of watering is wasted on such accumulation. Evaporation removes this water, for sure, if cycles longer than 30 minutes apply. 

    Maybe the algorithm can have some for of optimization where threshold for maxsoak time are set, e/g. soak more than 10 minutes but do not soak more than 30 minutes.  Any soak time is better than no soak time at all. 




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