- IFP & Organics
- Change Log
Accurate within about 20%, this method will give you a ballpark estimate of your irrigation application volume. Keep this in mind when you schedule your irrigation sets.
Obtain at least 16 identical pans with straight sides. Ensure water does not splash out the side when the irrigation is running. Avoid dark colored collecting pans as they heat up and lose water to evaporation. Ensure the cans are not so tall that the water hits the sides of the holder. For under-tree micro-sprinkler systems a short pan, such as a cake pan, must be used. For sprinklers that are higher off the ground, use a taller container like a coffee ground can. The more pans you use the more accurate your estimate will be.
For each irrigation zone, randomly spread the pans throughout a representative area with approximate uniform distance between them. Avoid placing pans under low branches that will drip into them, especially with under-tree sprinkler systems. You may need to place a rock in the containers to keep them from being knocked over by the irrigation. Remove the rock before measuring the water depth.
Turn on the irrigation for 1 hour.
Measure the depth of water in each pan and record it.
Find the average by adding the depths together and dividing by the number of pans.
If the application rates are very different in different parts of a zone upgrade/repair the system to even out the application as discussed above. Schedule your irrigation using the lowest average application rate. This will help ensure the trees in this area do not become drought stressed.
Sixteen coffee cans were spread around one irrigation zone. The irrigation was run for 1 hour and the depth was recorded in each pan.
Number of pans = 16
Total depth in all pans = 104 mm (4 in.)
Average depth: 104/16 = 6.5 mm (0.25 in.)
Water Application Rate = 6.5 mm/hr
The amount of water in the pans will vary – pans closer to sprinkler heads will have different levels compared to pans further away. Use your judgment to evaluate if the system is applying water uniformly. For example, pans in similar areas relative to the sprinkler heads should have similar water levels. Also, sprinkler patterns must overlap for uniform application.