318 Ecological Sustainability
a growth medium having two parts: a lower compost layer, which is cov-
ered by a second, top layer known as casing soil. The casing soil assists
in maintaining a desirable moisture level, CO
2
/O
2
ratio, and neutral pH.
Sphagnum peat (partially decomposed sphagnum moss) is widely used as
casing soil by most mushroom growers. In 2003, J.W. Stamp (2003) patented
a non-sphagnum peat casing soil formula for mushroom growth. Stamp’s
recipe called for approximately 6.25 parts by weight of sedge peat or coco-
nut ber (shredded coconut coir) peat and approximately 3.75 parts by
weight of sugarcane mill mud, adding water to adjust the moisture content
to approximately 75% and adjusting the pH to between 6.7 and