Heat And Drought Stress/Irrigating The Landscape
Heat and Drought Stress:
Our most recent trouble with trees in the Wichita area started with wet years in 2008 and 2009, which caused trees to lose their roots. Those trees needed their extensive root systems to soak up what little water was available during the drought years that followed. Those drought years were by far the worst thing that could follow root loss.
2011’s very cold and hot weather put another heavy hit on our trees. The weather of 2012 and 2013 didn’t cooperate either. In fact, city crews removed about 6000 trees in 2012 alone. That number doesn’t account for trees on residential or commercial properties. Due to environmental stresses, it’s estimated that we’ve lost almost 30,000 trees in the past 5 years in Wichita. Furthermore, when you have drought after drought years, you see the ill effects on trees for the next 2 to 5 years.
Now, in 2014, we have just experienced the driest start to a year on record! From January 1st through May 8th, only 2.01 inches had been measured at Mid-Continent Airport, making the first 128 days of 2014 the driest start to a growing season in 125 years!
All of our adverse weather has allowed disease and pest insects to flourish and suck the life out of sick, dry and environmentally stressed trees. Proper watering is the most important practice to help any plant recover from stress.
A general rule for watering newly planted trees is 10 gallons a week. If your soil is getting dry, be sure to water to a soil depth of 10 to 12 inches. There is no one correct watering schedule in the landscape, however, there’s an easy way to determine water needs. There is a great tool just for that purpose. It’s called a soil probe. Commercially referred to as a pipe probe, this tool is made by several companies. The probe works by feel. By pushing it into the soil, you can tell instantly whether the soil is too dry or too wet. Then the irrigation can be adjusted as needed.
For an affordable version of the moisture probe, break the head off an old or unwanted golf club. Making a clean sharp end by cutting with a hacksaw is best. What you should not do is make or use a probe that is all metal. Using an all metal probe made of re-bar or other metal without a rubber handle is dangerous. Electrical lines may be waiting for you! Push your probe into the soil and it will stop when it hits dry soil. In general, water trees planted in the last couple of years every week and all others every other week. Don’t keep trees constantly soaked, however. They will get root rot if the roots are drowning and can’t breathe.
Irrigating the Landscape:
Water companies are scaling their rates to increase as the quantity of usage rises. To have a green lawn in the dry summer months can cause eye-opening water bills. One reason for such a bill can be seen running down the street along the curb. Soils can reach a point of runoff quickly, especially when the soil is heavy clay or if areas are strongly sloped. In these circumstances our money often runs down the gutter.
If irrigating your landscape from a well, you may be facing a pretty challenging issue as well. Not only has the level in our water aquifer dropped significantly, but the depletion has enabled saltwater plumes from the Arkansas River and the old oilfields to invade our fresh groundwater. In some areas the aquifer water has become too salty to be suitable for either drinking water or landscape irrigation.
An effective watering method for those with automatic irrigation systems is to cycle through an abbreviated watering program and repeat it twice. This gives the soil a chance to soak up the first half of the water before the second starts again, allowing more of the moisture to penetrate deeply.
For example, let’s say that a rotor zone runs for 20 minutes each cycle, three days a week and temperatures demand that more water be applied. Instead of adding more minutes to the zone to get the job done, lower the watering time to 15 minutes and cycle the program twice in succession on the same day. The first 15 minutes has time to soak for the length of the program before the second round, allowing much more water to be absorbed. And, the minutes of water that you would have added to the single zone time has been saved and stays in your pocket, or our aquifer.
Why not just water 20 minutes a day, six days a week? It is proven that lawns are much healthier if the soils are allowed to dry out a bit between waterings. The drying allows oxygen to penetrate back into the soil to the turf’s root system, making roots grow deeper. Constant watering saturates the soil and cuts off the flow of oxygen, weakening the turf and making root systems much shallower.
Sloped areas are the toughest to irrigate, especially with slopes on clay soils. Runoff occurs most quickly on sloped areas. If a normal (“flat”) zone would run 20 minutes, program any zone on a sloped area to run the first two cycles 15 or 20 minutes and third cycle (on a separate program) 5 or 10 minutes.
A bit of tinkering and experimenting with your irrigation controller utilizing the Cycle and Soak method will save water, money and greatly benefit your landscape.