Fertilization Can Help Turf Withstand Traffic

Every landscape manager has them, places where turf just won't survive because people take short cuts. After all, the grass is there for them and you can't pave all of paradise. In desperation, you bring out the aerifier, apply extra nitrogen and turn up the irrigation to help these areas recover. You're right about the aerifier but wrong about the nitrogen and the water.

First of all, start about two months before people start thinking about wandering across your turf. Aerify the site and leave the cores on the surface. Keep the soil open to let spring rains infiltrate. Take a few soil samples and mail them to a lab for testing. Don't just look at the N, look at the P and K too.

Nitrogen, while important for growth, results in a higher tissue moisture content and softer leaves and stems if over applied. Potassium makes plant cells denser and more rigid, able to withstand wilting and weight from above. However, like nitrogen, it is subject to leaching, especially in sandy soils. Quick-release ammonium fertilizers, such as urea, ammonium nitrate or ammonium sulfate, also predispose potassium to leaching. This is one of the underplayed strong points of N sources like IBDU, ureaformaldehyde, methylurea, and sulfur- or plastic-coated urea. They don't promote potassium leaching.

Another thing to keep in mind is getting the turfgrass as mature as possible before the busy season. Phosphorous speeds up the maturation of the grass plant, so it is tougher, sooner. It does not leach, so you don?t need much P in the spring. Get a head start on turf growth before the trees leaf out in the spring. Mow often to encourage turf density.

As soon as you get the soil test results back, aerify again and fertilize with one of the slow-release N sources, the same rate of K, and a fractional rate of phosphorous (P). Ask the lab to make a recommendation for the iron, sulfur and calcium levels in the soil. Iron can provide color to turf without the lush effects of nitrogen. You might want to apply gypsum to improve calcium levels and soil structure. Use potassium sulfate for the source of K.

Consider topdressing with an amendment containing sterilized, well-decomposed organic material to protect the crowns of the turf plants from late winter freezes and winds, and traffic in a few weeks. Once you start topdressing, repeat every few weeks during the busy season. Compatibility of the topdressing with the soil is an issue. Brush the topdressing into the aerification holes with a mat.

Use your core sampler to check soil moisture depth. Don't jump to a summer irrigation schedule if the root zone stays damp for days. In fact, too much water might be part of the problem. Not only does wet soil compact easier under traffic, it looses nitrogen and potassium faster.

Turfgrass can only take so much pounding before it surrenders. If traffic or shade make it impossible to grow grass in a certain location, don?t hesitate to resod. That's what sod is for, after all. If you do sod, select a variety that has improved traffic tolerance and give it plenty of time to establish before the next picnic season begins. New sod needs to be kept wet and that doesn't fit the bill when people want to leave the pavement.