Agriculture Reference
In-Depth Information
Raw (fresh or dried) manures can contain human pathogens, and NOP
organic certification regulations do not allow raw animal manures to be ap-
plied to tree orchards within 90 days of harvest, or small fruit orchards with-
in 120 days of harvest. The NOP states that, for crops intended for human
consumption, raw manures must be
incorporated into the soils
at least 90 or
120 days, respectively, before harvest.
Both bat and bird forms of guano are allowed under the U.S. National Or-
ganic Program. Use these materials as you would other manures. Nitrogen
contents range from about 5 percent for bat guano to 13 percent for bird
products. Guanos also contain 8 to 12 percent P O and about 2 percent K O.
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These nutrients are available to plants at moderate rates and can be applied
as late as the spring for the coming growing season.
Composting solves many of the problems with manures, providing a
stable, relatively light (if bulky) material from which excessive salts have
been leached out. Composting various mineral products, such as colloidal
phosphate, with animal manures can make the mineral nutrients more avail-
able to plants. Proper composting also helps destroy potential human patho-
gens, such as
E. coli
bacteria. Manures can be contaminated with pesticides
used to control pests in and around barns, corrals, and feedlots. When ob-
taining composts or materials for making compost, ensure that they are
pesticide-free. Note that the U.S. National Organic Program prohibits the use
of ash from burned manures.
If you are meeting certification standards, be aware that the NOP has
specific requirements for composting manure so that it can be applied to
an orchard within the 90 or 120 days-to-harvest window mentioned above.
Composted plant and animal materials must be produced though a process
that establishes an initial C:N ratio of between 25:1 and 40:1, respectively.
The temperature must be maintained between 131 and 170°F (55-77°C) for 3
days using an in-vessel or static aerated pile system, or you must maintain
the temperature between 131 and 170°F for 15 days if you are using a win-
drow composting system. During the 15-day period, you must turn the ma-
terials a minimum of five times.
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