Reducing irrigation usage is the result of more than just the irrigation system. Go back to a basic economics course you’ve taken. Supply and demand are the main points of discussion in economics, and I like to look at irrigation the same way. Your irrigation system is the supply side, and your plants represent the demand side of the irrigation economy.
Saving water through leak prevention, adjustments to nozzles, sensors, etc. all impact the supply side of the equation. Don’t forget about the demand side. This is where we have made a lot of the improvements to our water usage. If you go back to my “3 ways to save water” post, the third way was to reduce your cycles. Most of us can reduce some cycles without impacting our turf. It’s just the way we are wired; typically human managers overwater their turf. Baseline irrigation has some studies on their website that shows that most managers over water by over 30%. I won’t disagree with that. I would have loved to have been off by only 30%.
After you have reduced your cycles and runtimes, the supply side, to a proper amount, the only way to reduce future cycles is to manipulate the plant and soil to demand less water. You do this though solid agronomic programs that takes water conservation into account. We have heavy clay soils throughout our property. My program would have to be heavily modified for sand based or loamy root zones.
Step one of our program was to aerify. I mean aerify a lot. We averaged aerifying biweekly during the summer season for two years. Now we are on a more normal program of 3 times a summer. Thatch is not an issue on our property, so we used solid tines set to 8 inches in depth. We can do 26 acres in 9 man hours with no cleanup needed, so this is not a major time investment. This has given us a soil that is capable of supporting root growth and water infiltration. It is common for clay soils in our area to have an infiltration rate similar to concrete, this has to be addressed. We will start our core aerification program next year.
Next was the use of wetting agents. I have my favorite, you will have yours. We use Moisture Manager from Ecologel Solutions. I have used it for years and we have added it to our monthly program. This allows the water we supply through irrigation to be better spread throughout the root zone. Also, it has an added benefit of converting soil humidity to soil moisture.
The last part of our agronomic program that helps to limit water demand was to increase root depth. We average root depth of over 8 inches, and typically reach 10+ in the growing season. With a root zone this deep and full, it is no wonder that we were able to reduce our irrigation usage so much. We are able to go 5 to 7 days after a rainfall before we show drought stress. IT is common in the summer for us to have another rain event in that period and we get to skip many scheduled cycles.
As you devise your methods for irrigation conservation, do not forget that it is a program. There are many pieces that need to be addressed. The irrigation components are some of the projects and comprise the supply side. The demand side is the plant, and you need to make it as healthy as possible. Increase your roots and help the water stick around instead of turning into runoff.