Agriculture Reference
In-Depth Information
Manure
It's a bit of work for city folks to find manure, but it does play an important role in the
compost pile for its nitrogen content and microbe population. A pile can be made without
manure, but it can be difficult to find enough food scraps and fresh plant matter to supply
adequate nitrogen. That being said, I've spent the last few years as a vegetarian and a ve-
gan, and certainly support using compost that doesn't contain manure if you prefer. In fact,
some research has shown that mad cow disease can be transferred from manure to mice.
Consequently, I have used horse manure instead of cow manure, but I can't find any in-
formation showing which animal manures are safe from this point of view.
Fresh manure should not be applied directly to the soil for several reasons. The high ni-
trogen content can burn plants, and nitrogen can leach into the water table and volatize into
the air. The high salt content can also cause problems. Other excess nutrients such as po-
tassium can imbalance the soil. Weed seeds that weren't broken down by the animals' di-
gestive processes can be spread throughout your garden too. Composting the manure in a
well-made compost pile helps with many of these problems. Some nitrogen is still leached
and volatized, but much of it ends up in the bodies of microbes. Composting manure first
means salt and excess nutrients are buffered and weed seeds are killed.
Different manures have different characteristics. A mixture of manures is ideal, but just
go with whatever kind you can get your hands on, keeping in mind the health of the source
animals. Non-organic farm animals receive antibiotics, hormones and dewormers, some of
which can survive the composting process. They certainly decrease the amount of benefi-
cial microbes that end up in the manure. Chickens may be fed arsenic and their manure
may have been treated with alum, which ties up the phosphorus, rendering it unavailable to
plants. Mushroom manure is horse manure that has been used to grow mushrooms. It may
contain huge amounts of pesticides and excess calcium, which is added to grow the mush-
rooms. Basically, we want organic manure.
Chicken, sheep and rabbit manure are generally considered the highest in nitrogen, and
horse can be good, too. Pig and cattle manure are lower in nitrogen, but cattle manure is
said to be rich in microbes. Even your own manure can be used if you're not taking phar-
maceuticals. The best places to go are where there will be manure that isn't going to be
used. Horse stables are a good bet and the manure is already mixed with straw, so it's very
easy to handle. Poultry and dairy farms are okay, too. Small hobby farms aren't as good be-
cause they probably use all of their manure on site. You can even go ahead and buy a few
bags of manure at your garden center, but it's already been composted and it may have
nasty substances added. Check the label.
