Miraculous Mulch

Just how big is 5,000 cubic yards? Imagine standing in front of a mound 51 feet tall, 51 feet wide and 51 feet deep. This mound would be taller than a typical New York City brownstone building. That's how much mulch the Central Park Conservancy's staff creates each year, all collected and processed from debris that would otherwise go to landfill: material from pruned trees and shrubs. The unprocessed material is passed through a wood chipper, at which point it becomes the incredible, moist, nutrient-rich substance called mulch. Mulch is so chemically active that piles of it generate heat, and can be seen steaming in cold weather. The Conservancy processes and stores the Park's mulch at our composting operation, located in the area of the Park called the Mount. The Mount is where both mulch and compost are produced in the Park. Compost is decomposed organic matter like garden refuse, kitchen scraps or grass clippings and leaves that get added to soil to increase nutrients. Mulch is spread on top of soil for a variety of benefits.

The Mount is as rich with history as mulch is with nutrients. The area is named for the Sisters of Charity of Mount St. Vincent, a Catholic convent and school located on the site before it was Central Park. As construction of the Park began, the Catholic order was relocated to a new home in the Bronx and the Park's designers, Calvert Vaux and Frederick Law Olmsted, moved in with their families. From 1862 to 1865, the building was used as a hospital for Union soldiers and the Sisters of Charity returned to nurse them. After the Civil War, the building was transformed into a museum, restaurant and garden, before burning down in 1881. Two years later, a restaurant was built on the site. A favorite of rowdy Tammany Hall politicians, McGowan's Pass Tavern was torn down by anti-Tammany officials in 1915. The site was dormant for decades until the Conservancy opened its composting operation in the early 1980s.

Since then, thousands of cubic yards of mulch have been collected, generated and stored at the Mount. Mulch is exceptionally useful. It increases the fertility of surrounding soil, both by leeching nutrients directly into the soil and through nutrients generated in decomposition. It insulates soil, keeping it cooler in the summer and warmer in the winter. It conserves moisture by reducing evaporation, which lets Conservancy staff use less water when irrigating plants. Mulch protects against soil erosion by slowing down the movement of water when it rains. By providing a buffer between the ground surface and soil, mulch makes it more difficult for seeds of invasive plant species to germinate, protecting trees and smaller plants from water and nutrition hogs. This buffer also reduces soil compaction, caused by footsteps and vehicles on the surface, which can inhibit plant growth. Finally, as mulch breaks down, it enhances the soil structure by making it more porous, which improves aeration, temperatures and moisture levels, all important for plant growth. Given all its uses, it's easy to see how the Conservancy's staff uses so much mulch.