Figure 6. Precipitation events with more than 2 inches per event for Virginia from 1900 through 2014. Figure taken from
https://statesummaries.ncics.org/va.
a straw mulch layer will absorb the raindrop energy, so the drops don’t hit the soil directly and then move into the soil slowly. Without the mulch cover, the raindrop energy can move soil once the infiltration of rainfall stops. Raindrops that directly hit the soil surface can destroy the soil aggregates and when that occurs, runoff begins to commence, and the seedbed is destroyed. Te mulch layer reduces the rate of water evaporation from the surface and maintains moister conditions in the seed zone to allow the seedlings to have access to adequate water for their initial growth. Tis is especially important in areas with limited irrigation and where seeding is occurring in times of the year with more infrequent precipitation.
Once the turf is established, the changes in precipitation during the year will continue to present challenges. Some of these will be the potential for increased snowfall during the winter with large amounts of melting in the early spring that could cause erosion in areas of the landscape with poor stands. Rainfall events on frozen soils will run off and could potentially cause problems downstream; however, turf as part of the landscape design could mitigate the impacts of these events.
Te variability in precipitation during the summer will present the greatest challenge because this is the time of the largest atmospheric demand for water and the most variable precipitation period of the year. In agricultural crops, this is the period when we see the most variability across fields and when we see the most variability in turf growth because the soil’s capacity to store water and make it available to the grass becomes very evident.
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In urban environments, the atmospheric demand will increase because of the increased temperatures that will increase the rate of water use by turf. Turfgrass producers well understand that plant water use depends on three components: the atmospheric demand for water, the supply from precipitation or irrigation, and the soil water reserve. Te latter depends upon the soil type and the depth of the rooting system of the turf. To maintain stands under the increasing variability of the water supply will require adaptation to utilize genetic material with more drought resistance.
Challenges and Opportunities Tere have been and will continue to be changes in precipitation amounts, frequency of storms, and intensity of storms. Tese changes will present challenges to the turfgrass industry in the establishment of turfgrass stands and the maintenance of stands. Awareness of the potential changes creates an opportunity to develop adaptation and management strategies to cope with the changing precipitation regime for any location. Tese will be site-specific practices; however, they will all involve management of the water that comes from precipitation in the most effective manner to ensure the viability of the turfgrass industry.
Jerry L. Hatfield is laboratory director and supervisory plant physiologist for the National Laboratory for Agriculture and the Environment, which is in Ames, Iowa. He can be reached by email at
jerry.hatfield@usda.gov.
TPI Turf News September/October 2019
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