## How much water does your lawn irrigation system apply?

### As dry conditions persist, knowing how much water your irrigation system applies is critical for maintaining healthy turf.

Most of Michigan is dry and there are plenty of brown, crunchy lawns to be seen. Irrigation is key to helping turf survive the heat and drought and knowing how much water your in-ground system or hose end sprinkler is applying will help ensure you’re giving the turf enough water. Follow these simple guidelines to determine how much water you’re applying and identify if your sprinkler system lacks uniformity of coverage.

1. Determine what your favorite type of canned food is and start saving the cans. We’re looking for straight-sided cans like soup cans, coffee cans, or if you’re a big tuna fan, those will work well also. Cans that are between 3 and 6 inches in diameter work best. Collect about five to 10 cans.
2. For the in-ground irrigation folks, spread the cans evenly throughout one irrigation zone – you can follow up with additional zones if you’re seeing trouble spots, but do one zone at a time. For the hose-end sprinkler crowd, place the cans in a straight line from the sprinkler to where the sprinkler coverage ends.
3. Crank-up the water for 15 minutes.
4. Grab a trusty ruler and measure the depth of water in each can.
5. For math challenged individuals like me, this is the tricky step. Find the average depth of all cans (simple math), add up all the depths and divide by the number of cans.
6. Continuing with “advanced calculus,” we now want to find the irrigation rate per hour. Multiply the average depth you calculated from #5 and multiply by 4. This gives you the irrigation rate per hour.

Also, take note that when conducting the above test you can get an idea of the uniformity of the water being distributed. If some of the cans have large amounts of water in them and others just a bit, the uniformity of the sprinkler may be poor. This is often common for hose-end sprinklers; the area near the sprinkler delivers more water than the perimeter. Make note of uniformity patterns and adjust sprinkler position to “cover-up” the misses.

Dr. Frank’s work is funded in part by MSU’s AgBioResearch.