Procedures that I recommend for proper watering depth.
Attaining the proper watering depth for your grass is a multistage process. I will go through each step by step.
1) Know your target depth: If you read my last blog post, you already know that for our area (Duncan Oklahoma) and type of grass , the target watering depth is about 6″. So six inches is our goal!
2) Setting up the measuring devices: Tuna anyone? Your probably thinking, “what kind of question is that?” I have found that the tuna can is a perfect measuring device. They are abundant (if you like tuna that is) and easy to work with. You can also use cat food cans, but since I am a dog man, tuna it shall be! You want to set out 6-7 tuna cans throughout your front yard. Space them evenly out where they can give you a snapshot of where your irrigation system is covering. Just watching this first process can give you a lot of insight on how well your irrigation system is supplying water to your whole yard. Once this entire process is followed you can then repeat it on the back yard.
3) Calculate the depth of water in 30 minutes: Once the cans are in place, turn on your sprinklers. Time the sprinklers for 30 minutes. Once the time has been reached, turn off the sprinklers. Use a ruler and measure the depth of water in each can, write down the results of each can. Add the results of each can’s depth together, then divide by the number of cans used. Look at the example below.
Can 1 .4 inch
Can 2 .6 inch
Can 3 .5 inch
Can 4 .6 inch
Can 5 .4 inch
Can 6 .5 inch
Total 3 inches
Divide the total amount of water (3 inches) by the total number of cans (6)
3 ÷ 6 = .5 inches per 30 min
4) Find the amount of depth of the soil that is wet: Using a screw driver, garden spade, or any other soil probe, probe down into the soil to locate the depth at which the soil stops being wet. Lets say for an example that the soil is wet to the depth of 2 inches. We now know that 2 inches of soil was wet for a half inch of water applied. Which means in this example, we would need to water for an hour and a half to reach the the six inch target depth. For a consistent result, probe once near each tuna can location.
I feel at this juncture that I need to stress that the above is an EXAMPLE. Each irrigation system and lawn is different. You must actually do this procedure to be certain what your unique system delivers and needs.
Another word of caution. As I have stated in previous blog posts, in the Duncan Oklahoma area, we mostly have a clay based soil. This soil type is not conducive for good soil drainage, which leads to water run off. Obviously while irrigating your lawn if run off is occurring, you are wasting water. This waste can actually be significant, which is not good for the environment or your wallet.
5) Be observant on the initial watering: Now that you know the amount of time you need to water your lawn it is imperative that you are very observant, at least on the initial watering. You do not want to water any faster than your lawn can absorb that water. In our above example we needed to water for a hour and a half. However, if after 45 minutes of watering run off begins, you should stop watering and wait about thirty minutes. After thirty minutes continue watering until you have reached the hour and half time period. or until run off occurs again. If run off happens again, stop and wait another thirty minutes before completing the remaining time.
6) Make a plan and follow it: Once you know the above information, you can set automatic timers and make a educated plan on how to effectively water your lawn. Once the timers and plan has been set, follow it! Don’t let your emotions get in the way of that plan. If you know what to look for, and you should if you read my previous blog post, you can have an effective and economical irrigation strategy.