Sweet Auburn: The Magazine of the Friends of Mount Auburn Environmental Leader and Innovator | Page 15

From mid-May into June, compost creation begins
with feedstock consisting of landscape waste. The collected
items are shredded and mixed, and then turned over every
three days for two to three weeks. The compost mix is
monitored to maintain steady moisture and a temperature
of 131F that ensures weed seeds and pathogens are killed.
Subsequently, the mix is moved to another area to finish
cooking and then to cool.
Landscape maintenance and composting continues
throughout July, August, and September. Turf is mulched
in place in most areas. Grass clippings are collected from a
small number of sites to pump nitrogen into the compost.
Waste from small shrub pruning also becomes compost
feedstock.
Near the end of October, leaf pickup begins. For more
than a decade, Mount Auburn has been using mowers fitted
with mulching (Gator) blades to mulch leaves where they
fall. Allowing the chopped material to decompose in place
raises the organic-matter component of the soil and reduces
the need for synthetic fertilizers. In addition, about 1,200
cubic yards of leaves are collected in a designated area in
the recycling yard and turned monthly for a year. Eventually
the aged leaves are used for mulch, added to topsoil, and
serve as a carbon feedstock for compost.
The finished compost made during the summer is screened
during the fall and then used for top-dressing new graves,
for fertilizing turf areas, and in potting mixes. A small amount
of compost is used to brew compost teas, in which a stew
of compost and water promotes the rapid reproduction of
beneficial bacteria and fungi. Using compost teas, we can
deliver these microorganisms to more areas of soil than we
could reach by broadcasting or spreading solid compost.
In just two years, Walker managed to change the habits of
the grounds crew; to create an efficient operating recycling
yard; to develop recipes for compost and topsoil that are
suited to Mount Auburn’s landscape; to purchase equipment
of appropriate scale for Mount Auburn’s manufacturing
operations; and to eliminate materials costs for topsoil,
compost, and mulch—an overwhelming success.
tween 10 and 20%. More recent soil testing at Mount Auburn
has shown a slight improvement in the organic-matter con-
tent, and we expect it to continue an upward trend.
The words of Dr. Jacob Bigelow—medical doctor, botanist,
and co-founder of Mount Auburn Cemetery—remind us
that decomposition is an essential part of the great cycle of
life. “What has once possessed life is most assimilated to the
living character, and most ready to partake of life again,”
Bigelow opined in 1831. “The plant which springs from
the earth, after attaining its growth and perpetuating its
species, falls to the ground, undergoes decomposition and
contributes its remains to the nourishment of plants around
it…Were it not for this law of nature, the soil would soon
be exhausted, the earth’s surface would become a barren
waste, and the whole race of organized beings, for want of
sustenance, would become extinct.”
Organic Matter
How has the soil responded? Twenty years ago, Mount
Auburn’s soil testing was predominantly focused on turf
conditions and the physical properties of sand, silt, and
clay components; acidity (pH) was measured, as were the
proportions of five macronutrients and nine micronutrients
for growing particular crops or landscape plants. The initial
2004 testing found an average of 6.1% organic-matter in
the soil. While this figure fell within the range of 4–10%
that the state extension office recommends for most plants,
we felt the organic content could be coaxed higher. For
example, at Arnold Arboretum, where grass clippings have
never been collected, organic-matter content ranges be-
This aerial view shows a part of the Mount Auburn landscape many
visitors have never seen. Located next to our greenhouse, our recycling
center is responsible for processing more than 400 yards of mulch and
125 yards of loam. Get the full story online: www.mountauburn.org/
sweet-auburn-summer-2014/
Summer 2014 | 13