Composting of manure is of special interest in watersheds that supply drinking water to cities, such as those that serve New York. The parasites Giardia lamblia (beaver fever) and Cryptosporidium parvum cause illness in humans and are shed through animal manure, especial y young stock. These organisms are very resistant in the environment and are not killed by chlorina-tion. Composting of manure, however, is an economical option that kills the pathogen and protects drinking water.
ADVANTAgES OF cOMPOSTINg
There is evidence that compost application lowers
Composted material is less bulky than the original
the incidence of plant root and leaf diseases, as men-
material, and easier and more pleasant to handle.
tioned. In addition, the chelates and the direct hormone-
During the composting process, carbon dioxide and
like chemicals present in compost stimulate the growth
water are lost to the atmosphere and the size of the pile
of healthy plants. Then there are the positive effects on
decreases by 30–60%. In addition, many weed seeds
soil physical properties that are derived from improving
and disease-causing organisms may be killed by the
soil organic matter. These are some of the broad benefits
high temperatures in the pile. Unpleasant odors are
to plant growth that are attributed to compost.
eliminated. Flies, a common problem around manures
If you have a large amount of organic waste but not
and other organic wastes, are much less of a problem
much land, composting may be very helpful and may
with composts. Composting reduces or eliminates the
create a valuable commercial product that improves
decline in nitrogen availability that commonly occurs
farm profitability. Also, since making compost decreases
when organic materials, such as sawdust or straw, are
the solubility of nutrients, composting may help lessen
added directly to soil. Composting is also very useful for
pollution in streams, lakes, and groundwater. On many
recycling kitchen wastes, leftover crop residues, weeds,
poultry farms and on beef feedlots, where high animal
and manures. Many types of local organic waste, such
populations on limited land may make manure applica-
as apple pumice, lake weeds, leaves, and grass clippings,
tion a potential environmental problem, composting may
can be composted.
be the best method for handling the wastes. Composted
material, with about half the bulk and weight of manure,
and a higher commercial value, can be economically
The reasons for composting and using composts need
transported significant distances to locations where
to be balanced by good practices such as locating
nutrients are needed. In addition, the high temperatures
the pile to minimize runoff and possible pollution
and biological activity during the composting process can
of surface waters. Compost piles may produce odors
help to decrease antibiotic levels in manures, which can
when turned, so it’s best to site piles away from where
be taken up by crops growing on manured land. Compost
neighbors might get a more powerful whiff than they’d
can also be stored easily, so it can be applied when soil
like. Composting in dry regions or under cover may
and weather conditions are optimal.
produce composts that contain relatively high levels of
Without denying the good reasons to compost,
salts, and you may need to apply them at lower rates
there are frequently very good reasons to just add
to avoid damaging plants.
organic materials directly to the soil, without compost-
ing. Compared with fresh residues, composts may not
148
Building SoilS for Better CropS: SuStainaBle Soil ManageMent