[niv]

Today something interesting happened Here, we had high winds from the Egypt, which carried a lot of dust.

The result was a sharp change in the PM:

Feb 8 – PM was 2

Feb 9 – was 0.3

Feb 10 – was 3.7

I am validating the PM I query, so I won’t run the irrigation for ever in the case a bird builds a nest over the meteorological sensor.

So it emailed me today to tell me a sharp factor was found between the last day and today.

I adjusted the thresholds , and the system recovered.

[niv]

Hi Ken,

I had the same issue when starting up with open sprinkler.

see https://opensprinkler.com/forums/topic/irrigation_bone-irrigate-exctly-the-amount-of-water-needed/

[niv]

Some explanation to what I did:

I wanted a program to run unattended on the device, that will increase irrigation on hot days. I found the Penman-Monteith coefficient. It a number that is calculated by the amount of solar radiation, wind, temperature. you can get his number from a close by meteorological station.

For example here are such a website in Carolina: http://www.nc-climate.ncsu.edu/openwaterevap

Then you just need to make this simple calculation: Plant coefficient X area X PM coefficient = amount of litres to irrigate

Plant coefficient: 0.5 for grass and 0.7 for roses, what do you grow?

Area in square meters

Assume its a hot day here the PM may reach 6. Assume My plants coefficient is 0.6, and i have 10 square meters, I will water the garden with 6X0.6X10 = 36 litters that day.

I usually irrigate an hour after the sunset because then the air humanity rises, so water loss is minimal.Also the plant outer “skin” opens up to accept water.

Now if you water too much, you also end up hurting plants. So I started to seek a way to measure the exact amount of water I irrigate.

[niv]

Idea is simple. Fetch daily evaporation coefficient near where I live. Multiply by  plant coefficient, multiply by area, and get the mount you need to irrigate.

Here is where to get the coefficient for north carolina  : http://www.nc-climate.ncsu.edu/openwaterevap

 

[niv]

This program proved to work fine for two weeks while I was on vacation. I left the water sensor a bigger garden to prove it works, I see a lot of reading even whn the electric faucet is turned off.

[Author]

Posts