Is there an optimal irrigation algorithm for lawns?

Other Devices & Integrations Water, Pool & Irrigation
1

This might be a naive question, but is there an optimal irrigation algorithm for grass given past rain, expected rain, past temp and future temp?

I would think that if it is really hot and sunny you would need less water on your grass then if it is average or cooler than average. Therefore given weather data could you develop a Irrigation Factor (F) for each day that ranges from 0 to whatever. Assuming that on average you want to put X amount of water (liters, gallons, minutes of watering, whatever) then on any given day you would be F*X. If F was 1.1 you would be putting on 10% more water than usual and if F was .9 you would be putting on 10% less. And if F was 0 your sprinkler would not run.

I would think that someone would have done research into this area - certainly for golf courses if not for other purposes.

2

I looked into this when I started to set up my watering controlled by vera.

When applying water, it makes sense to bring your topsoil to its saturation point, and no more.

So when determining when to water, it comes to dry days, RH, temperature,the makeup of your topsoil, type of grass, etc, all of which affect the moisture remaining in the soil.

Most of what I read led to putting moisture sensors in the soil at the bottom of the roots and watering when it gets dried out. Grass is healthier when the roots are allowed to dry out as it prevents fungus and other cooties from assaulting the roots.

Of course, I am dealing with water restrictions nearly year round, so I look for localized rain and the sensor readings to cancel watering on my allowed days if I don’t really need to water.