Spring and early summer months bring warm sunshine and blooming flowers. Sometimes, however, these warmer months also bring damaging rainfall and flooding events that devastate turf grass and sports fields. Here’s what you need to know to help your turfgrass recover from springtime flooding.
Factors that Impact Turfgrass Survivability
Every turfgrass species differs in its ability to tolerate and survive flooding events. A few variables impact the survivability of each species.
Water temperature is a significant factor. Turfgrass tends to survive better when the floodwater and air temperatures are cooler. Turfgrass can survive up to 60 days submerged under floodwaters when the water is around 50 degrees. When water temperatures are 86 degrees or warmer, however, the grass will likely die within 24 hours and new sod will need to be planted.
Floodwater depth is another major survival factor. If any of the leaf tissue is above the waterline, the grass will likely survive. Plants that are completely submerged in water can die from a lack of oxygen and light deprivation.
Once the turf or lawn is submerged underwater, it doesn’t take long for soil oxygen levels to be depleted. When the oxygen levels decline, the root will begin to die and the grass will not be able to absorb nutrients, water, or oxygen.
Standing floodwater also allows sediment to collect on the grass blades, leading to turfgrass injury. For this reason, slow-moving floodwater is often less damaging to turfgrass than stagnant floodwaters.
Relative Submersion Tolerance Rating
Each species of turfgrass, whether it be Kentucky bluegrass or fine fescue, is different in its ability to survive flooding. While there are no hard, fast numbers regarding their survivability, each species is assigned a “relative submersion tolerance” rating.
Creeping bentgrass, for example, has an excellent relative submersion tolerance rating. It is often seen floating on the edges or growing in the middle of ponds and lakes. Kentucky bluegrass and tall fescue receive a “medium” rating. Poa annua and perennial ryegrass are “fair,” and red fescue brings up the rear with a “poor” relative submersion tolerance rating.
Assess submersion injury to turf grass
To assess floodwater damage to turfgrass, collect several plants from the flood area and cut them horizontally through the crown. If the crown is brown and soft, the grass has died. If the crown is white and firm, the grass is still alive and viable.
Steps to Help Turfgrass Recover
Remove debris and sediment
Once the water recedes, the first step in the cleanup process is to remove large debris and sediment. It is very difficult to remove all traces of sediment, so it is best to use a variety of methods to break up the sediment layer and encourage root recovery.
If large amounts of silt, soil, sand, or clay are left behind, remove as much as possible with a flat-bladed shovel or rake it across the turf. You should not till the silt or sediment into the root zone.
Slicing or hollow or solid tine aeration can help with the drying process, which improves the condition of the soil and increases oxygenation to the rootzone.
Sediment layers that are less than an inch thick can be very difficult to remove. After the layer completely dries, a drag mat will break up the sediment. Follow the drag mat with aggressive hollow tine aeration and topdressing to prevent the sediment from clogging the rootzone.
Evaluate the soil and grass
Once the debris and sediment are removed, begin assessing the damage. Fields that suffered extensive damage may need to be tilled, re-graded and reseeded, or sodded. Fields with less damage may only need some soil cultivation to return to normal.
After the core cultivates, topdressing will level the turf surface and help dilute any remaining sediment. It also helps improve the rootzone. Make sure the topdressing material matches or is slightly coarser than the particle size of the existing rootzone.
Flooding causes nutrients like nitrogen, lime, phosphorus, and potassium to leach out of the soil. Conduct soil tests and create a fertilization plan. Fertilizing after flood waters recede is important to promote turfgrass growth and recovery.
Nitrogen and phosphorus stimulate recovery and improve overall stress tolerance in the turf. Use a quick-release form of nitrogen. Phosphorus will help with seedling growth.
Replant, seed, or sod
Depending on the extent of the damage, some fields may need to be replanted to facilitate growth and recovery. Fields with minimal damage may only need a spot-seeding or light over-seeding.
Fields that suffer moderate to major damage may need seedbed preparation and heavy over-seeding. Areas with the most severe flood damage may need to be sodded. If properly installed, sod can allow for play within weeks or a few months.
In the summer months, if flood damage occurs to a game field during the playing season, choose thick-cut sod for the fastest recovery time. Thick-cut sod allows for the field to be playable within hours instead of weeks or months.
Maintaining Your Turfgrass
Prevent weeds and disease
Floodwaters often deposit weed seeds on turf fields. If the fields only suffered minimal damage, apply pre-emergent or post-emergent herbicide to control weed infestation.
Hot, humid weather and saturated soils are the perfect environment for diseases to develop in turfgrass. Keep an eye out for developing fungal diseases and use the proper fungicides as needed.
Synthetic turf cleaning
While synthetic turf fields are not directly damaged when submerged under floodwater for long periods, flooded areas can cause carpet displacement, infill displacement or loss, contamination, and debris and sediment deposits.
Some sediment is easier to remove when wet and other types are easier to remove when dry. Clean the sediment as quickly as possible and practical.
Severe flooding may cause the synthetic turf to wrinkle. The fabric needs to be stretched and repositioned. Restore the infill to the proper levels and perform a Gmax analysis to ensure the field is safe for play.
Flooding can very easily lead to the contamination of artificial fields. Use proper topical sprays to decontaminate the field and prevent bacteria from growing.
Contact Kenney Machinery
Kenney Machinery has the tools and equipment that you need to help you recover from spring flooding. No matter the turf maintenance project that comes your way, Kenney Machinery can offer a helpful solution. Get in contact with us today for more information or to request a demo.