October 4, 2016
Five Things You Didn’t Know About The National Mall’s New Lawn
After years of being “loved to death” by visitors from around the world (33 million on particularly busy years) the National Mall has undergone a $40 million makeover. The National Park Service’s most visited park now boasts a verdant lawn consisting of eight grass panels on 18 acres. It’s a transformation overseen by the U.S. government’s first Turf Management Specialist, Michael Stachowicz, who was hired away from a long career on Massachusetts golf courses. From Stachowicz, otherwise known as the nation’s “grass guru,” here are five fascinating facts about America’s new and improved “front lawn”:
1. It’s filled with sand — lots of it
The new grass, a mix of Kentucky bluegrass and tall fescue varieties, was custom-blended and grown at a New Jersey sod farm. Most of the root zone installed on the Mall is sand — about 80 percent of it — with 10 percent topsoil and 10 percent peat (decomposed organic vegetation) mixed in. “We picked the most wear-tolerant turf we could find,” Stachowicz said on the Kojo Nnamdi Show. Its sand-based root zone is key to making it durable since sand naturally resists physical compaction. Sand also provides space for air, water and root growth.
2. It’s fertilized with seaweed and worm poop
In early spring and fall, the lawn gets an application of chicken manure compost to keep it fed. But during summer growing months, crews apply a tasty biweekly mix of seaweed extract, worm excrement, iron and urea. Stachowicz says the blend promotes good root growth resulting in a more healthy and sustainable stand of turf. To control weeds, Stachowicz applies a low-impact herbicide — one that won’t meddle with grass seeding.
3. It has a powerful irrigation system
Before its renovation, a maze of sprinkler heads crisscrossed the Mall, often suffering damage from foot traffic, errant balls, vehicles and tent stakes. The new irrigation system has been simplified: each panel has one sprinkler head down the middle and two down the side that throw water 90 feet. The system turns on every other night (bring your umbrella if you’re out for a romantic stroll between midnight and 4 a.m.). An automated weather station monitors temperature, humidity, wind and soil moisture, varying the amount of water applied depending on the turf’s moisture needs.
4. It recycles water
The Park Service installed four new 250,000-gallon underground cisterns which collect water run off from the lawn. The water cycles through a disinfection process with UV treatment before it’s returned to the irrigation system. Stachowicz says in theory, the cisterns are designed to supply 68 percent of the Mall’s water needs, which should provide enough water to irrigate for two weeks if there’s no rain.
5. It stays perky with lots of mowing
Lawn care slackers may roll their eyes, but one of the most important tools for keeping the Mall’s new lawn healthy is mowers — which run twice a week with sharp blades. “Grass wants to be a hayfield of seed heads, so you mow it before you see it needs mowing,” Stachowicz says. He compares it to training a bonsai plant or pruning a hedge. “Mowing when it goes to seed or gets too tall is a shock to the system. So if you mow it, never removing more than a third of the plant, you will have increased density and that helps the grass to stand up and be resistant to traffic,” he says. “The plant takes the energy it would be putting into sending up a seed stalk and puts it into growing more grass blades, resulting in an upright carpet of grass.” The density from regular mowing also helps grass fight weeds like crabgrass.