The UMass Turf Program’s own Dr. Scott Ebdon this week delivered a great lecture on water management and water conservation… a highlight from our 2022 Spring Kickoff education program. When attention turns to conserving water in turf management, some ponder why water conservation deserves much bandwidth in the generally cool, humid Northeast region.
In the big picture, water is a finite natural resource, and conserving it is a mainstay of responsible management. Despite higher average annual precipitation rates relative to some other regions of the country, there is a trend in the Northeast for increasing frequency of drought events. This, coupled with population growth, means that water not used for drinking or food production is often the first to be limited when water restrictions are implemented.
On a management-level scale, the meteorological summer months of June, July, and August (also sometimes referred to as the “irrigation season”) comprise the most stressful period for the cool-season grasses that are otherwise well-adapted to this region. While water can be a vital tool for turf survival and meeting stakeholder expectations, greater water use also frequently equates to greater expense. Fortunately, decades of objective research have refined practices designed to promote increased turf performance while simultaneously conserving water.
To paraphrase Dr. Ebdon from the aforementioned lecture: it seems out of place to be thinking about water conservation this early in the game, especially coming off of the record-bending rainfall totals that many regional locations received in 2021. Turns out that while a lot of turf is just beginning to show signs of life, a well-rounded, effective approach to optimizing water use begins at the very start of the growing season. Much of the equation concerns rooting: roots are central to moisture acquisition, drought avoidance responses, and overall plant resiliency, which places rooting among the most important aspects of water management.
Spring is when cool-season grasses produce most of their annual root mass. Root capacity also slides under the high soil temperatures of summer; therefore spring is prime time to have root development high on the priority list. The following are some management considerations to promote better rooting, and by extension, water conservation:
Turfgrass selection: Grasses better adapted to the growing environment will have greater overall health and vigor, which translates to greater rooting. There is also variation in inherent rooting capacity among turfgrass species and varieties; grasses with a genetic propensity for better rooting will capture moisture more readily and exhibit higher drought avoidance characteristics. Take stock of what you’re working with now: if the grasses present are a less than great fit for the setting, consider planning for overseeding, renovation or reconstruction with better adapted species and varieties in late summer.
Soil Conditions:
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Test soil and employ proper liming practices. pH values approaching 5.0 and lower can restrict both root growth and root activity. pH in the neutral range also maximizes mineral nutrient availability, especially essential micronutrients.
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Regular aeration supports rooting in several ways including better water infiltration, better gas exchange with the atmosphere, and relief from excessive thatch and soil compaction. Aeration is a disruptive practice, however, and should be performed only when adequate conditions for recovery exist, typically in late summer. Aeration and other cultivation activities performed in the spring can bring weed seeds to the surface during the time of maximum annual weed pressure, and can potentially affect the performance of any prior preemergence weed control applications.
Mowing: Particularly during the favorable period in the spring, mow if possible at the high end of the appropriate range for the species and use of the turf, as rooting depth and density are roughly proportional to mowing height. Cutting too low, or too frequently, shrinks leaf area which translates into reduced photosynthetic capacity, and less photosynthetic capacity can support less root mass and depth.
Fertility: Use measured fertility matched to the individual circumstances and time maximum nutrient availability to correspond with peak growth periods.
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Too much available nitrogen can result in excessive vegetative (shoot) growth which occurs at the expense of root growth. High nitrogen rates may yield vibrant green color and vigorous growth in the short term, but these benefits are typically unsustainable due to negative impact on the root system over the longer term.
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Phosphorus is essential for new tissue development, especially root tissue. Test soil to determine needs for supplemental P, if any (excessive P rates can contribute to water pollution).
Watering: It may seem counter-intuitive at first, but deep, infrequent irrigation is much preferred to frequent, shallow irrigation. Irrigating often, and in short bursts, only serves to wet the soil to a shallow depth. Allowing the soil to dry down between irrigation events helps to condition plants and stimulates root expansion, thereby promoting a deeper and more extensive root system and greater overall resiliency. Consider a wilt-based irrigation approach to build plant resiliency throughout the season
Pesticides, especially herbicides: Some herbicides can affect the roots of desirable turfgrasses, especially preemergence herbicides when used at high rates or when turf is not fully mature. Employing practices within a weed management program to minimize the use of herbicides can help to promote root vigor. Be sure to time herbicide applications accurately, avoid applying outside of the proper weather conditions as specified on the product label, and avoid blanket applications in favor of spot applications whenever possible.
Submitted by: Jason D. Lanier
