March 8, 2010

Burning Lawns: A good idea or bad idea?

Using fire to burn dormant turf is a means of eliminating dead leaf blades on bermudagrass and zoysiagrass swards. This practice was historically used on some turf areas including golf courses, but now it is seldom used on golf courses except for native areas (taller mown wildflower areas). I recently received a question on this topic, so I thought I would address it in this week’s turf tip.

Burning your lawn with fire is a practice some sometimes used by rural homeowners in the late winter and early spring. Reasons (advantages) for burning your lawn would include 1) removing dormant/dead leaf tissue, 2) reduction in thatch, 3) possible reduction in pest populations, and 4) enhanced spring green-up. The main advantage is that there will be some enhanced spring green-up because the existing leaf tissue is removed and the soil is warmed quicker from the dark color of the charred lawn. It is not clear how well this process works to remove thatch since heat from the fire is limited in duration and limited to the surface and these controlled burns often do not change the soil temperature deeper in the soil profile.

Disadvantages of burning a lawn include 1) damage to surrounding ornamentals, 2) damage to your or other property from fire, 3) legalities of burning in your city/counties, 4) burn restrictions or burn bans, 5) coordination with your local fire department, 6) air pollution, 7) not all turf species can be burned without causing damage to the turf, and 8) an unsightly mess of black soot in your lawn until spring temperatures permit turf growth.

Some native prairies are managed with controlled burns (prescribed fires). Controlled burns help breakdown organic matter (leaves, sticks, logs) causing a release of nutrients back into the soil. Fire is an inexpensive tool which can be used faster than mowing in some cases. Fire can also control some undesirable weed species. However, lawns and other managed turf areas typically do not have these large quantities of organic matter and other debris which makes this technique not as useful or necessary in managed turf. Questions you might ask yourself is 1) Do high quality athletic fields and golf courses burn their turf?, or 2) Would my insurance agent approve of this burning activity? The answer to both is no.

Although burning a lawn will not harm the lawn and burning lawns can result in some benefits, the potential negatives outweigh the positives. Only those trained in controlled burns should use this technique on their lawn.

A better strategy is to use your lawn mower to help enhance your lawns spring green-up. Before bermudagrass and zoysiagrass begin to grow in the spring, you can mow the turf slightly shorter (1 or 2 notches lower on your mower) than normal to remove dead leaf blades. This practice will reduce shading of the emerging plants and also serve to warm soil temperatures more quickly in the spring. The result is a lawn that greens-up more quickly in the spring. The risk in this practice is that 1) you could scalp some of the emerging grass if this practice is delayed until after the lawn has begun to green-up, 2) this practice could increase weed seed germination if the soil is exposed to sunlight, and 3) if too many clippings are removed then they will need to be disposed of in a land-fill or composting facility. Carefully inspect the turf before removing dead leaf tissue and debris to ensure there are no green shoots emerging. Zoysiagrass lawns often do not go fully dormant like bermudagrass during winter. Therefore, spring scalping is likely to be more damaging on a zoysiagrass lawn than a bermudagrass lawn. Low mowing in early spring is damaging to centipedegrass and St. Augustinegrass lawns since they spread by above ground stems (stolons) and are more prone to injury from this practice. The practice of spring scalping should not be used on cool-season turfs like tall fescue or Kentucky bluegrass.

Dr. Aaron Patton

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