MANURE IS AN EXCELLENT
developing a manure by-product market is important to
understand that manure is a necessary by-product of the
livestock industry and it is the technology involved in
the treatment system that determines whether manure is a
valuable resource or a costly liability.
The simple fact is,
untreated manure is simply animal feces while properly
treated/processed manure is a value added marketable
organic residual. Technological factors involved in
manure treatment systems have a significant influence on
by-product quality and it is the quality that dictates
In addition to
agriculture, the potential markets for high quality,
composted manure products include horticulture i.e.
gardening, landscaping, nurseries, topsoil production -
silviculture i.e. Christmas trees, ornamentals -
reclamation i.e. landfill covers, mine reclamation and
other environmental uses i.e. biofilters, erosion control
and wetlands restoration to name a few.
Manure as a
Manure is an excellent fertilizer containing nitrogen,
phosphorus, potassium and other nutrients. It also adds
organic matter to the soil which may improve soil
structure, aeration, soil moisture-holding capacity, and
To determine how much
manure is needed for a specific application, the nutrient
content and the rate nitrogen becomes available for plant
uptake needs to be estimated. Nutrient content of manure
varies depending on source, moisture content, storage,
and handling methods.
Nitrogen content in manure
varies with the type of animal and feed ration, amount of
litter, bedding or soil included, and amount of urine
concentrated with the manure. Moisture content is also a
major consideration. For example: The moisture content of
fresh manure is around 70% to 85%. The moisture content
of air-dried manure is around 9% to 15%. As manure dries,
the nutrients not only concentrate on a weight basis, but
also on a volume basis due to structural changes
(settling) of the manure. Volatilization of urine
nitrogen can result in considerable loss of nitrogen, up
to 50% or more of the total nitrogen.
Generally, dry manure
contains 1.5 to 2.2 cubic meters per ton. Dry poultry
and steer manure contain around 1.9 cubic meters per ton.
Handling can affect the fertilizer value of
manure, particularly its nitrogen content. Nitrogen is
present in manure in a variety of forms, most of which
gradually converts to ammonium and nitrate nitrogen.
The ammonium form can be
lost to the air and the nitrates leached by rainfall.
Ammonium losses can be minimized by not stockpiling
manure while it is moist, minimizing its handling, and
working it under immediately after spreading. Ammonia can be lost to
the air each time manure is moved or hauled. Much of the
loss is from hydrolysis of the NH2 groups
(enzymatic) and then volatilization of N20 and
NH3. This loss can be very high when spreading
manure, especially during warm, dry weather. Here, at
least 50% of the ammonium nitrogen can be lost within 12
hours. Studies have also shown that, by one week after
spreading, almost 100% of the ammonium nitrogen can be
lost. This loss can represent up to 50% of the total
nitrogen available in stockpiled manure.Therefore, the
importance of simultaneously spreading and working in
manure is obvious.
Availability and Manure Application
Manure is a source of many nutrients including: nitrogen,
phosphorus, potassium and many others. However, nitrogen
is often the main nutrient of concern for most crops.
Potassium deficiency is usually quite localized within a
field and would not be corrected with common rates of
manure. However, some improvement might be expected with
high rates above 10 tons per acre. The high rates needed
to correct a potassium (K) deficiency would supply an
excess amount of nitrogen for many crops, and this should
be avoided. (See Table 1)
of Manure for Nitrogen Needs
The nitrogen compounds in manure are eventually converted
to the available nitrate form. Nitrate is soluble and is
moved into the root zone with water. It is the same form
ultimately available to plants from commercial nitrogen
release of available nitrogen from the complete organic
compounds during manure decomposition is very gradual.
This slow release of nitrogen is manure's most important
asset. It extends nitrogen availability and reduces
leaching -- of particular importance in sandy soils.
The idea is to
first apply enough manure to meet the first year's need
of available nitrogen. Decreasing amounts are then
applied in following years because of the carry-over
organic nitrogen that will be released from previous
applications.If the same rate of manure is applied each
year, it is possible for a field originally low in
nitrogen to accumulate unnecessarily high levels in
The nitrogen in
poultry manure is in released fastest, about 90% is released in
the first year.
which contains both the urine and solid portions and has
a large amount of urea or uric acid provides a somewhat
slower release rate, with approximately 75% of the total
nitrogen released the first year.
An even more
gradual nitrogen release can be expected from dry feedlot
steer manure, with only 35% of the total nitrogen
released the first year.
Benefits of Manure
The use of manure helps to maintain the organic matter
content of the soil which can improve soil structure and
water infiltration. However, manure is quickly decomposed
under warm, moist soil conditions. With the manure rates
used for most crops, organic matter content in soil is
only temporarily increased.
Weed seeds are common in some manure. They may enter the
animal with its feed and then pass through the digestive
tract, still viable, or they may have come with the
litter, or they may have simply blown into the feed yard.
droppings typically have fewer weed seeds surviving the
digestive processes. However, other animal manure may
contain numerous viable weed seeds if the original feeds
were contaminated. Composting and stockpiling manure can
reduce the number of viable weed seeds.
contain 4 to 5% soluble salts (dry weight basis) and may
run as high as 10%. To illustrate, an application of 5
tons of manure containing 5% salt would add 500 lbs. of
irrigation and rain water will sufficiently leach
well-drained soils to prevent damaging salt
accumulations. However, one should be cautious with
poorly drained soils, soils with existing salinity
problems, or unusually high application rates, especially
when concentrated near young plants.
can be induced or increased with repeated high rates of
manure, especially on sandy soils.
infrequent applications do not normally present a zinc
problem. However, growers should be aware of the
potential problem, especially with soils and varieties or
crops of known susceptibility to zinc deficiency.
The principal value of manure is its extended
availability of nitrogen -- of particular value in the
more readily leached sandy soils. Manure is also helpful
in improving soil fertility in cut areas from land
and rate of availability varies widely, depending mostly
on manure source, handling methods, and water content.
Fresh manure which includes both liquid and solid
fractions with the least handling and then work in
immediately after spreading will retain the most
nitrogen. A laboratory analysis of the manure for
nitrogen content is useful. An accurate sample of the
manure requires a composite of many samples throughout
the pile or lagoon.
poultry manure is highest in nitrogen content, followed
by hog, steer, sheep, dairy, and horse manure. Feedlot,
steer manure requires fairly high rates to meet
first-year nitrogen requirements because of its lower
nitrogen percent and gradual nitrogen release
feature provides for more continued nitrogen availability
in succeeding years, allowing for progressively lower
annual application rates to meet plant requirements.
nitrogen-release sources, such as poultry manure, require
more constant and lower annual rates to maintain nitrogen
advantages of organic matter content and disadvantages of
weed seed and salt content should be considered in using