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Components And Uses Of Poultry Manure
Poultry
manure
management
management
Dr William Stiles: IBERS, Aberystwyth University.
Take home messages:
· Poultry manure is rich in nutrients making it an effective
fertiliser.
· Initial composting can improve the nutrient composition of
this material.
· Guidance should be sought from the APHA before moving it
between farms.
Poultry production is a growing sector of agriculture in the UK,
due to the increasing demand for poultry meat and egg products.
Poultry manure is a by-product of this production and is rich in
nutrients, which can provide a major source of nitrogen (N), phosphorus (P) and
trace elements for crop production.
This material can also improve physical and biological fertility
of soil, making it ideal for land application as a fertiliser.
The
availability of poultry manure is growing rapidly, particularly in Wales, making
its usage in agricultural production more commonplace.
However
the effectiveness of poultry manure as a fertiliser has been questioned due
to low carbon (C):P and N:P ratios and the high potential for loss of N and P
through leaching.
In
addition, overuse or unplanned applications can result in nutrient saturation
and consequently environmental loss.
Initial
soil testing and defined nutrient management plans for fertiliser application
are therefore essential.
Finding effective ways to manage this potential resource
is therefore of key importance to enable a strategy for effective waste
management, and also to maximise farm business efficiency.
Composting poultry manure:
Composting poultry manure prior to
application can potentially improve nutrient constituent ratios and produce a
more predictable and reliable source of N and P, which remains as
available after composting as in the fresh litter material.
Composting
poultry manure might have additional benefits such as the decomposition of
veterinary drugs.
This
may be an important factor as the uptake of veterinary medicines by plants has
been reported as a potential consequence from the use of poultry manure.
Different
feedstock materials for composting alongside poultry manure have been trialled
to attain optimum nutrient ratios.
In
a study comparing different feedstock materials, compost produced from mixing
poultry manure with wood chippings and bark (42.5%), wheat straw (30%) and
grass clippings (20%) had the highest quality as a soil improver in terms of
organic matter content, C:P ratio, C:N ratio and stability.
Interestingly,
the poultry manure component was relatively small (7.5%) in order to achieve
optimum nutrient ratios.
Other
studies have demonstrated the effective use of a higher rate of inclusion of
poultry manure.
In
one, a mixture of 83% poultry manure and 17% wheat straw (dw) provided the
best conditions for the composting process out of three ratios tested (the
others were: 73.5% manure/26.5% straw and 88% manure/12% straw).
Nevertheless,
the addition of C rich material is necessary to avoid low C:N ratios in the
compost mixture, which may inhibit the composting process.
Temperatures
generated by this mixture during composting were also shown to be sufficient
for pathogen removal.
Alternative uses for poultry manure:
Spreading fresh manure on the land
can result in emissions of greenhouse gases (GHGs), such as N2O.
Alternative
strategies for using the manure material could be the generation of
electricity. This reduces the emission of GHGs from the manure and also reduces
the emissions of GHGs associated with fossil fuel combustion.
In
addition, the resultant ash is rich in P and K and can still be used as a
fertiliser.
The
use of biochar derived from poultry manure has also been shown to be
effective for use as a fertiliser in bean and maize crops.
This
approach may offer a mechanism to reduce the problems associated with use as a
fresh manure, whilst also generating energy and subsequently increasing C
storage in soil after application.
Nutrient management planning and factors to consider:
Due to a variable composition,
unprocessed (or ‘green’ manure) presents several difficulties in terms of even
spread of nutrients during land application.
In
addition, the high levels of N and P means that application rates must be
restricted to avoid nutrient leaching.
Long-term
applications of poultry manure may also affect soil P status, ultimately
leading to losses of P.
Poultry manure from different poultry
farming systems varies in composition due to the nature of farming practices
between systems.
Poultry
litter from floor-raised birds (broilers, turkeys, broiler breeder pullets)
consists primarily of droppings and bedding (usually wood shavings or sawdust).
Feathers
and waste feed make up the remaining litter components.
Poultry
manure consisting of only faecal droppings is associated with caged layers and
broiler breeders.
A
study of poultry manures from different systems from across the UK showed
that, in general, broiler/turkey litters had a higher dry matter content
(c.60%) than layer manures (c.35%), although all manure types had similar
concentrations of nutrients (N, P, K, Mg, S) on a dry weight basis.
Typically
N:P:K ratios were 6:2:2 for layer manures and 6:2:3 for broiler/turkey litters.
Current rules/regulations on the use of poultry manure:
According to information on GOV.UK:
to sell manure there are several stipulations which must be met.
For
sale in the EU, it must first be treated at an approved processing plant, where
manure must be heated to 70°C for at least 60 minutes.
Approval
must also be sought from the Animal and Plant Health Agency (APHA).
It
is possible to use alternative methods of processing, but these will need to be
ratified by the APHA and subsequent analysis of the resultant material
(including tests for bacteria, virus and parasite presence) will be required.
For
sale in the UK, partially processed material can be sold. Approval will still
be needed from the APHA for this practice.
However,
the distribution of material which isn’t commercially exchanged may still be
acceptable.
The website stipulates that ‘you can
spread poultry manure on your own land or supply it for use on other farms and
markets gardens if you take the following steps to avoid the spread of
botulism: inspect your birds regularly and remove any dead ones from the litter
immediately so carcasses don’t end up in the manure; don’t dispose of feathers
or cracked eggs in your manure (some feathers will naturally fall into the
litter but don’t dump bulk quantities, e.g. after the slaughter of turkeys at
Christmas)’.
The
burning of poultry manure in a combustion unit also requires prior application
to the APHA.
It
is recommended therefore that guidance is sought before commencing with the
movement of manure between farms or any other distribution activities.
Summary
The growth of poultry production within
the agricultural industry, both in the UK and globally, will ensure supplies of
poultry manure will also grow concurrently.
A
major challenge for this growing sector is the management of this substantial
waste burden, which, if managed correctly, is a valuable resource of nutrients.
Poultry manure has the potential to
be a highly effective fertiliser, as it has a high nutrient content.
The
use of green manure may however be problematic due to the relative ratios of
nutrients within this material.
Initial
composting of this material can improve these characteristics and the resultant
compost material can be stored for longer periods and is easier to apply in
field than unprocessed chicken litter.
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