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K-State Turf and Landscape Blog

Category: Irrigation

Wet Spring will Likely Lead to Quick Drought Response as Summer Approaches

Posted on by Teresa Roberts

By Jack Fry, Professor and Commercial Turf Extension Specialist

It’s been a wet spring through much of Kansas.  In Olathe, KS there has been 11.3 inches from March 1 to June 10.  Frequent rainfall reduces the necessity for grasses to produce deeper roots, and also enhances more shoot growth.  As summer approaches and an extended period of time without rainfall occurs, drought stress will be occurring more rapidly that it sometimes has.

Uniform irrigation is important so that water is distributed nicely over a lawn, golf course, sports field, or other area.  In addition, you can estimate the amount of water that has been lost from the turf over time, which is called evapotranspiration (ET).  Evapotranspiration includes water evaporation from the soil and transpiration from the leaves.  Here is a site from Kansas State University that provides weather information and allows you to determine the level of ET that has occurred:

https://mesonet.k-state.edu/

You can click on the location near you on the KS map when this website comes up.  Then, go to the upper left corner of mesonet (click on the 3 lateral bars) and select any information desired.  To determine water use, go to weather – historical weather – enter the dates that are of interest for you.  After doing so, click submit and you’ll see weather details returned.  On the far right of the image, click on grass ET and you’ll see an estimate of ET for that area.  Here’s an example of the ET that I looked at for Olathe, KS:

The ET that you see is based upon a formula called Penman-Monteith, which uses temperature, humidity, solar radiation, and wind to create the estimate.  As a reminder, the ET that you view is based upon assumption that the soil moisture is high.  In other words, as soil dries down in a turf area, the ET is likely going to be lower than estimated on this site.  That said, this information is useful to provide guidance on the amount of irrigation that may be needed to apply to the turf area. To confirm the amount of water applied from your irrigation system, use a sprinkler gauge that indicates the amount of water applied for a given amount of time.

Deeper, less frequent irrigation will enhance rooting as time progresses.   To do this, you may desire to wait until you begin to see wilt occurring on the turf.  As an alternative, you can determine what the soil moisture measurement is when wilt is just beginning and irrigate just prior to that soil moisture level.  As summer heats up and less rainfall begins, it is quite likely that following this strategy will still require irrigation be applied often due avoid extensive wilt.  It is possible that over time, irrigation frequency can be reduced.

There are number of different research articles below that demonstrate all turf species can get enhanced rooting with a deeper, less frequent irrigation strategy.

Tall Fescue:

Huang, B. and J. Fu.  2001.  Growth and physiological responses of tall fescue to soil surface drying.  Intl. Turfgrass Soc. 9:291-296.

Fu, J., J. Fry, B. Huang.  Tall fescue rooting as affected by deficit irrigation.  HortScience 42:688–691. 2007.

Creeping Bentgrass:

Fu, J., P. Dernoeden.  2009.  Creeping bentgrass turf response to two summer irrigation practices: rooting and soil temperature. Crop Sci. 49:1063-1070.

Jordan, J.E., R. H. White, D.M. Vietor, T.C. Hale, J.C. Thomas, and M.C. Engelke.   2003.  Effect of irrigation frequency on turf quality, shoot density, and root length density of five bentgrass cultivars.  Crop Sci. 43:282-287.

Zoysiagrass:

Qian Y. and J. Fry.  1996.  Irrigation affects zoysiagrass rooting and plant water status.  HortScience 31:234-237

Above is the photo from the zoysiagrass research noted above in 1996 (a number of years ago). The zoysia on the left had been irrigated daily for an extended period of time and then water was turned off.  On the right, zoysia had been irrigated deeply and infrequently (based upon ET measurement) and then water was turned off.  Obviously, the deeper, infrequent irrigation enhanced its tolerant to drought.

Water Saving Strategies

Posted on by Jack Fry

Wes Dyer, Ph.D. and Manoj Chhetri, Ph.D. both finished their doctoral degrees at K-State in 2021; each had focus on water savings as part of their research. Wes is employed with Irrometer Company, Inc. in Riverside, CA and Manoj is a horticulture extension agent for the University of Missouri.  Dr. Cathie Lavis joins them to present strategies for saving irrigation water on this video recorded at the 2021 Kansas Turfgrass Field Day.  Hear about the effectiveness of soil moisture sensors in contributing to water savings, and how irrigation heads differ in water delivery.  To view, click HERE (about 15 min.).

Watering Landscape Ornamentals

Posted on by Brooke Garcia

By Dr. Cheryl Boyer

It’s that time of the year when it’s both very hot and, likely, very dry. While it’s important to water landscape ornamentals all year long, now is a critical time to make sure plants have all the resources they need.

We have several publications about best practices for watering:

Newly planted trees (within their first year) should be watered at least weekly but check the soil to make sure it’s draining well. Slow-release watering methods like micro-pore bags and 5-gallon buckets with small (1/8-inch) drainage holes are a good way to apply irrigation to trees and some shrubs. However, remember to remove the bags when they are empty to ensure good airflow around plant stems and reduce pests and diseases. Removing turfgrass and other ornamental plants to at least the tree dripline (or beyond) will help trees access more water and grow more quickly—make sure to mulch the turfgrass-free zone to help retain applied water.

Established trees will benefit from a thorough soaking (to a depth of 12 inches out to and beyond the drip line) every 3 to 4 weeks. Established shrubs need water every 2 to 3 weeks during this drought- and heat-prone time of year. Plants growing in raised beds and berms may need to be watered every 1 to 2 weeks. Soaker hoses work well for watering established trees and shrubs.

You may want to consider taking advantage of a light rainfall (if you get one in July and August) by watering immediately afterward to help moisture move deeper into the root zone.

Any way you slice it, watering is a good thing. There are many other factors to consider for successful planting, but right now watering is top of the list. Keep it up—plants are thirsty just like you!

It is time to…..WATER, WATER, WATER!

Posted on by Brooke Garcia

By Brooke Garcia

The temperatures are reaching summer high’s this week, and it is more important than ever to be monitoring and increasing watering schedules. Adjusting irrigation settings to accomodate for extreme temperatures will be vital for the health and survival of new plantings, as well as established plantings.

Featured in the Horticulture e-Newsletter, Ward Upham discussed the importance of watering for trees and shurbs. The article is featured in the link here.

Here are some other timely blog posts about watering as well:

Drive Your Car Without a Fuel Gauge?

Posted on by Jack Fry

By Wes Dyer (Ph.D. student)

The dreaded check engine light popped on this past month. Bound to happen to a 15-year-old vehicle, pushing a quarter of a million miles. I immediately stopped by a local auto parts store and connected a diagnostic scanner to find a faulty fuel level sensor. Not the worst diagnostic error, but I knew I had to be more aware of the miles I drive between refueling. It reminded me of a quote by Dr. Dana Lonn, former managing director for technology at Toro Company, in which he states, “controlling an irrigation system without soil moisture data, is like driving a car without a gas gauge.” I realized more than ever what he meant as I found myself making more frequent stops at the gas station to refuel this past month, just to be sure.

The rootzone profile is much like a fuel tank, where adequate water, or “fuel”, is needed in the profile to maintain a healthy turfgrass stand. How do you know when to refill your soil profile? Setting irrigation clocks to specific days of the week to water is prone to lead to overwatering, like myself now, making more stops than necessary to refuel the vehicle. Even calculating daily evapotranspiration rates (which are estimates of the water used by turfgrass) fail to accurately account for moisture in the soil profile. Utilizing technology and devices to determine soil moisture is much like a fuel level sensor that can aid in determining when the plant needs water. This is where implementing technology in the landscape has advantages. The greater period you can stretch between irrigation applications, the greater chance a rainfall event will occur which will serve as “free water”, though I do not anticipate free gas events.

Soil water sensors are like a fuel gauge – necessary! Both wired and wireless are available.

For the past three years, I have been working to determine how to best employ technology in the turf landscape. Soil moisture sensors are one of many tools we can use to precisely determine when irrigation is needed to maximize water savings, increase turfgrass quality, provide consistent playing conditions, and minimize overwatering. Research results from 2020 indicated soil moisture sensor-based irrigation yielded 84% water savings compared to frequency-based irrigation (2x week-1) and 72% savings compared to deficit evapotranspiration (60% ET) irrigation. These significant water savings were achieved by simply monitoring soil moisture and watering only when necessary to “refuel the tank.” For more information as reference to this project, see this past article (Development of Irrigation Scheduling Techniques that Conserve Water in Turfgrass Landscapes using Soil Moisture Sensors and Weather Data. Kansas Turfgrass Foundation Newsletter, September 2019).

Throughout my turfgrass management career, I have had the opportunity to work with many great golf course and athletic field facilities across the United States. Many of those managers took on the philosophy to be data-driven because it removes the guesswork. The more data available at one’s fingertips the better decisions one can make. The key is not to become overwhelmed with the data, however, but to use the data to aid in improving your decisions or as a “tool in the toolbox”. Regarding irrigation, automated systems may become more widespread in the future and use sophisticated technology to control irrigation. Until then, we can use the current technology to establish our own automated irrigation decisions. I often like to think about two or three simple questions before I choose to irrigate. Specific questions and thresholds center around soil moisture data, turf canopy conditions, and future precipitation forecasts. Certain criteria must be met before the irrigation is turned on which has achieved significant water savings while maintaining turfgrass quality. As my research nears an end, I think it is time to schedule that service on my fuel level sensor.