SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
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Q&A Native soils for overwintering bermudagrass BY DR. GRADY MILLER Professor, North Carolina State University Questions? Send them to Grady Miller at North Carolina State University, Box 7620, Raleigh, NC 27695- 7620, or email grady_miller@ncsu.edu Or, send your question to David Minner at Iowa State University, 106 Horti- culture Hall, Ames, IA 50011 or email dminner@iastate.edu. Q currently have one Riviera bermuda- grass soccer field on a sand-based field that is 2 years old and is per- forming superbly. We are getting ready to convert two of our cool-sea- son practice soccer fields to bermuda- grass. These fields are native soil (high clay content with poor drainage). My question is on the na- tive soil fields without any amend- ments how will the bermudagrass establish, perform, and [survive] winter on the native soil fields as compared to the sand-based field? Sam Jones At the University of Delaware we I'm glad Riviera is performing so well. I would have been a little skittish to recommend someone use bermudagrass that far north. With 3 months per year with aver- age lows below freezing, I am sure you get your share of harsh tem- peratures that could potentially winterkill bermudagrass. Riviera has proven to be more cold toler- ant than most bermudagrasses, so hopefully it will continue to meet all your expectations. As for the question, native-soils Sam, this is a great question. fields are often much easier to get established in turf than a sand- based field. The heavier soil will hold nutrients and water better, so there is generally a greater margin of error for grow-in, except if you get a lot of rainfall and cannot get the water off the field. Hopefully you are allowing for the reduced internal drainage by using a bit more crown and also putting some perimeter drainage around the field to get excess water away from the sidelines/playing surface as quickly as possible. 46 SportsTurf | November 2012 native soil field should compare fa- vorably to the sand-based field. Since there is a greater amount of water in the native soil profile it will cool down slower at night when the temperature drops. This is due to the specific heat of water being about four times that of air, plus air is a poor thermal conduc- tor. Generally, soil thermal proper- ties are very closely linked to soil moisture. For that reason, early season cold snaps normally cause more problems with sand-based fields than native soil fields. But once the cold temperatures arrive without adequate solar energy to promote warming during the day, it will not make as much difference. In the spring, the characteristics that may have helped you in the fall can work against you in the spring. It can take a bit longer to warm up high-moisture holding native soils, especially if ice and shade are involved. I've seen shaded portions of fields keep an ice cover for a week longer than the sunnier portions. Remember, I'm talking about North Carolina winters and early springs, where it is still con- sidered mild by many people's standards. Once the field has ade- quately warmed up, the thermal properties of water again gives the advantage to native soil fields. So, like in early fall, those late spring cold snaps may hurt the sand- based fields more than nearby na- tive soil fields. But there can be extenuating Winter turf survivability in the circumstances related to soil condi- tions that can reverse these re- sponses, resulting in more damage to native soil fields. The amount of traffic and any resulting damage to the plant and soil's structure can worsen the situation. The higher water content of native soils often results in more traffic damage, then muddiness, and perhaps sealing of the surface. Standing water is never good for turf health. And heavier soils compact easier from foot traf- fic or maintenance equipment than sandy soils. So, it is even more im- portant with heavier native soils to stay on a good aerification pro- gram. For an added bit of insurance invest in some good turf covers for the winter. lowed to dry out in the spring. Much of the late spring winterkill we see is often associated with des- iccation of the turfgrass combined with freezing temperatures. Spring winds combined with low humid- ity and freezing night temperatures can do more turf damage than a se- vere mid-winter drop in tempera- tures when the turf is fully hardened to the cold. You best bet for winter surviv- ability is to practice good cultural practices—irrigation, fertilization, aerification, and pest control—and limit on-field use as much as possi- ble during periods of high stress. For an added bit of insurance in- vest in some good turf covers for the winter. These not only reduce heat loss, they also help to keep people off the fields. But stay in this business long enough and you will likely get to experience win- terkill. On the positive side, bermudagrass-growing weather fol- lows right after bermudagrass- killing weather. So, my final suggestion is to have some seed ready to plant. ■ Fields should also not be al- www.sportsturfonline.com