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.
Issue link: https://read.dmtmag.com/i/560546
www.stma.org September 2015 | SportsTurf 19 fall applications of nitrogen to cool sea- son grasses should contain 30 to 50% controlled-released nitrogen, especially on sand-based fields. Late fall applications are best when shoots have begun to slow in growth (but remain green), promot- ing root growth. Late fall applications of nitrogen have also shown to have an impact on root development in the spring. Precautions for late season applications on cool-season grasses include the poten- tial for increased snow mold and winter annual weeds (annual bluegrass, henbit, chickweed, etc.). Understand that phos- phorus and potassium applications in the fall is not as critical for timing when cor- recting soil needs or when just including some amount as part of a complete fertil- izer. Fertilizers should never be applied to frozen ground as the potential for runoff is greatly increased. On the warm-season front, research has indicated that late season (fall) nitro- gen applications to bermudagrass will not contribute to winterkill. Maintaining adequate levels of potassium in the medium to high range is important for winter protection. However, studies have shown that additional applications of potassium in the fall, when sufficient levels already exist in the soil, will not increase winter hardiness of bermu- dagrass. Here a soil test can save on that purchase of a winterizer if potassium levels are found to be adequate. If potas- sium is needed, applications should be made well ahead of warm-season grasses slowing down in growth. So, late season applications of nitrogen to bermudagrass will allow for more recovery, maintain green color longer, help to build carbo- hydrate reserves and not contribute to winterkill. One precaution to note with fall applications of nitrogen to bermu- dagrass is the increased potential for spring dead spot disease. Avoid late season applications if spring dead spot is beginning to or historically occurs at your facility. Late season nitrogen appli- cations to bermudagrass fields can also contribute to increased winter annual weeds. Regardless of how well you developed your fertilizer program, if application techniques (swath and overlap) and calibration (half rate applied in two directions) are not properly followed, then you will realize the lack of unifor- mity in about 7 to 10 days! ■ ST Brad Fresenburg, PHD, is assistant exten- sion professor the University of Missouri in Columbia. See stma.org for "Understanding Soil Tests," "Late Fall Fertilization of Athletic Fields," from Penn State, and "Fertilizers," University of Tennessee, Extension Publication W161-E. 2008.