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PART V. CHOOSING FERTILIZERS AND SOIL TREATMENTS
A.
General Principles
There are several factors to consider when choosing soil
treatments and fertilizers. These relate to: the way in which
they will be applied, as well as to the precautions that you
will need to take whilst storing them.
Application methods range from aerial spraying (used for
forestry, or large expanses of crops) to tractor based and
manual methods. There are restrictions in the Member State Laws
as to when, where, and how you can apply fertilisers, especially
if your farm is close to a village, or a school.
When considering storage, it is important to realise that many
fertilisers are “fire accelerants”. That means that whilst they
are not necessarily explosive by themselves, they can increase
the intensity of any fire that they get caught up in, and will
increase the flammability of anything in their immediate
vicinity. Some can also become unstable in extremes of
temperature. You must store them with this in mind.
Many fertilisers include ammonia, or ammonium salts. These
fertilisers have the capacity to be toxic and cause severe skin
and eye damage.
And even “natural fertilisers” like manures have the scope to
harbour bio-toxins and infectious agents. Legislation and
guidance on the use of manures concentrates on the protection of
“ready to eat foods” from contamination by micro-organisms and
toxins in manures (see section 5.2). But if you, or your
workers, handle these products during harvesting and packaging
then you too may be at risk.
In the following sections we provide some guidance prepared by
regulatory agencies and the International Labour Organisation
which should help you to be more aware of the dangers inherent
in fertilisers and soil treatments.
B.
UK Guidelines on the Management of Farm Manures to
Ensure Food Safety
Farm
manures (both solid manures and slurries) are applied to
agricultural land to meet crop nutrient requirements and to
improve soil fertility. Around 90 million tonnes of farm manures
are applied to approximately 4 million hectares of agricultural
land each year in the UK. These manures can contain pathogenic
microorganisms (e.g. E.coli
O157,
Salmonella, Listeria, Campylobacter, Cryptosporidium
and
Giardia) which
may cause foodborne illness. The number of microorganisms in
manures is affected by factors such as the age, diet and
management of animals, as well as regional and seasonal
influences.
The
management and handling of farm manures, particularly the length
of time they are stored, are important factors in the survival
of microorganisms. The method and timing of manure applications
to land can affect the length of time that pathogens survive in
the soil, and the likelihood of their getting onto food crops.
In order to reduce any risks of foodborne illness resulting from
the use of farm manures, there is a need for due diligence in
the growing, harvesting and packing of ready to eat crops.
What Crops Pose the Greatest Risks?
The
microbiological contamination of crops that are unlikely to be
cooked before they are eaten is a risk to human health. Such
crops include salads, fruit and some vegetables - commonly
referred to as ready to eat crops. Crops with a short growing
season, such as salads and strawberries, are particularly
vulnerable. Up to 10% of the area growing ready to eat crops may
receive farm manures prior to planting.
Washing crops thoroughly after harvest will significantly reduce
the risks of foodborne illness. However, not all crops are
routinely washed so other precautions must be taken.
Sources of Microbial Contamination
Contamination by farm manures may occur through:-
-
Application to land before a crop is established
-
Application to growing crops
-
Runoff from solid manure field heaps
-
Leaking or overflowing solid manure stores and slurry lagoons
-
Transfer via contaminated equipment and vehicles
-
Aerosol or windborne contamination
-
Contamination of surface and irrigation water by livestock or
manures.
-
Livestock having access to cropped areas
What Kills Pathogenic Microorganisms?
Pathogens can be killed either in the manure itself or after
application to land. The main factors that will lead to a
reduction in numbers are:-
-
Temperature
–
in general, the higher the temperature the greater the level
of kill, with temperatures above 55oC
being particularly effective.Freezing can also reduce numbers.
-
Sunlight
–
exposure to sunlight and in particular ultra violet radiation
will significantly increase die off.
-
pH –
microorganisms generally survive best at a neutral pH. A low
pH (acid) or high pH (alkaline) environment will speed up the
rate of kill.
-
Drying –
microorganism numbers are generally reduced by drying.
-
Time
–
pathogenic microorganisms die out over time. The rate at which
this happens depends on environmental conditions. In some
conditions they can survive for several months.
STAGE 1 – MINIMISING RISKS BEFORE CROP ESTABLISHMENT
Pathogens such as E.coli
O157 can survive in soil for several months following
the spreading of farm manures or deposition during grazing. They
may also be present in dirty water, yard runoff and leachate
from stored manures.
Site Selection
You
can minimise the risks of microbiological contamination by
careful choice of where you grow the crop. Where possible:-
-
Avoid fields that have recently received manure or have been
used for livestock grazing. This may be difficult where the
nutrient supply and soil conditioning benefits of manure are
fundamental to the system. Consider if you can adopt a
rotational manuring policy and apply manures before a lower
risk crop, such as a cereal.
-
Minimise the risks of airborne contamination, by choosing
fields that are not adjacent to livestock units.
-
Avoid fields where there is a risk of surface runoff from
yards or manure storage areas.
Use of Fresh Manure
You should NOT apply fresh manure to land where you intend to
grow ready to eat crops, unless there will be at least a 6
months period between the manure application and harvest
Dung
deposited by livestock should also be considered as a potential
source of pathogens.
You should leave at least a 4 months gap between livestock last
being in the field and harvest of a subsequent ready to eat crop
Use of Stored and Treated Manure
The
batch
storage of solid manures and slurries for at
least 3 months (i.e. no additions of fresh manure are made to
the store during this period) or ‘active’ treatment, are
effective methods of killing pathogens.
Composting
is a
particularly effective method of controlling pathogens in
solid manures, but
for best results needs to be actively managed. Turn the manure
regularly (at least twice) either with a front-end loader or
preferably a purpose built compost turner. This should generate
high temperatures over a period of time (e.g. >55o C for 3 days)
which are effective in killing pathogens.
Other
forms of ‘active’ treatment, which are particularly suited to
the treatment of slurries
and can result in a significant reduction in
pathogens are:-
-
anaerobic digestion
(typically at 30-35o C with 12 days retention for pig slurry
or 20 days for cattle and poultry slurry).
-
lime treatment
(addition of quick lime or slaked lime to raise the pH to 12
for at least 2 hours).
You should NOT apply batch stored or treated manures to land
where you intend to grow ready to eat crops, unless there will
be at least a 2 months period between the manure application and
harvest
Land Application and Soil Incorporation
To
make best use of manure nutrients and to minimise air and water
pollution, you should follow advice in the relevant Codes of
Good Agricultural Practice (see Sources of Information and
Advice).
Design and locate manure storage areas to ensure that water
pollution risks are minimised. This should include adequate
containment measures.
Apply
manures uniformly and with due regard to the environment.
Observe any no spreading zones (e.g. next to watercourses or
boreholes) identified in a Farm Waste Management Plan. This will
minimise the risks of runoff and indirect contamination of
nearby crops. Keep a detailed record of manure application date,
type and rate.
Although pathogens can be killed by exposure to sunlight, you
should incorporate manures into the soil as soon as is
practicable, as this will reduce the potential for direct crop
contamination and also reduce odour and ammonia emissions.
In summary:
-
You should
select fields carefully so as to minimise the risks of
indirect contamination via surface runoff from manure heaps
and stores, or following the land spreading of manures
-
You should NOT
apply fresh solid manures and slurries within
6
months
of
harvest
-
You should NOT
apply treated or batch stored solid manures and slurries
within
2
months
of
harvest
-
You should
allow at least
4
months
between livestock last being in the field and harvest
STAGE 2 - MINIMISING RISKS AFTER CROP ESTABLISHMENT AND DURING
THE GROWING SEASON
Manure Applications
Manure should not come into direct contact with ready to eat
crops during the growing season.
Do NOT apply manure to ready to eat crops during the growing
season Field Operations
Avoid
spreading manure on neighbouring fields if runoff will be a
potential source of contamination of growing crops. Spreading is
a potential source of wind borne contamination. Use low
trajectory equipment and do not spread manures on windy days
upwind of ready to eat crops.
Whenever working in ready to eat crops ensure that equipment is
clean. Do not drive vehicles
through any manure or effluent on the way to the field.
Irrigation and Water Use
Water
used on the farm is a potential route of microbiological
contamination. It is very important that manure storage areas
and field heaps do not contaminate watercourses or sources of
irrigation water.
Keep Livestock out of Growing Crops
As
far as possible, you should prevent livestock from having access
to ready to eat crops. Where necessary, check that fences and
hedges are stock proof. Ask the public to keep dogs on leads
where footpaths run through cropped areas.
In summary:
-
Do NOT
apply manure to ready to eat crops during the
growing
season
-
Do
store solid manures and slurries well away from growing areas
-
Do
avoid contamination of growing crops e.g. from aerosol and
windborne drift during manure spreading, or by runoff from
adjacent fields where manure has been spread.
-
Do
ensure water sources used on the farm are not contaminated
with pathogens
-
Do
ensure all equipment (including vehicles) is clean
-
Do
keep livestock out of cropped areas
STAGE 3 – MINIMISING RISKS AFTER HARVEST
The
following guidance should be read in conjunction with other
advice on good worker hygiene, packing and storage protocols and
maintenance of temperature regimes.
Harvesting
Ensure that all harvesting machinery and equipment are clean. Do
not drive vehicles through any manure or effluent between the
field and the packhouse.
When
you harvest ready to eat crops, make sure that containers and
packaging are clean.Take particular care if the crops are packed
in the field and will not be washed. Keep all animals and birds
out of packhouses and storage areas.
Produce Washing
The
main risks of contamination after harvest relate to the possible
contamination of water used for washing or transporting produce.
Use only potable water for washing produce and transporting
produce in flumes.
In summary:
-
Ensure all equipment (including vehicles) is clean
-
Only use potable water for washing produce and transportation
flumes
-
Keep livestock away from packing and storage areas
-
Ensure staff observe good hygiene practices
STAGE 4 - GENERAL MANAGEMENT
You
should include the handling, storage and application of farm
manures in your assessment and control of microbiological
hazards, and in your Control of Substances Hazardous to Health (COSHH)
assessment.
Record all manure applications on a field by field basis
detailing the type, rate, date of application, source and
management of the manure before spreading.
Always follow Good Agricultural Practice and guidance in the
relevant Codes (see Sources of Information and Advice)
You
can obtain further guidance on worker hygiene and ways to
minimise the risks of microbiological contamination from amongst
others, the Fresh Produce Consortium.
In summary:
-
Do
include manure handling, storage and application in your
assessment and control of microbiological hazards, and COSHH
assessment
-
Do
record all manure applications on a field by field basis
-
Do
make all manure applications according to guidelines in the
relevant Codes of Good Agricultural Practice.
C.
Safe Storage and Handling of Anhydrous Ammonia
Anhydrous ammonia is commonly used nitrogen fertilizer
(82-0-0). It is pure ammonia gas (NH3)
compressed into a liquid form under high pressure. When
injected into the soil, anhydrous ammonia quickly returns to a
gas and dissolves in soil moisture. Anhydrous ammonia is very
dangerous if not handled correctly. Over the years a number of
farmers have been badly injured or killed while applying
anhydrous ammonia.
 Hazard:
Exposure to the liquid can cause frostbite. Exposure to high
concentrations (2,000-3,000 ppm) of the gas can cause severe
burns in a very short time. The gas will quickly react with
water in the skin, eyes and the respiratory airways. It forms a
substance that in sufficient quantities is very corrosive and
can cause serious burns to these tissues. The eyes, which are
80% water, are particularly vulnerable. A small amount of
anhydrous ammonia in the eyes is extremely painful and can cause
blindness. Inhaling large amounts can cause the lungs to fill
with fluid (pulmonary edema), which may lead to death by
suffocation.
Ammonia can be smelled by most people at concentrations below 25
parts per million (ppm) which is the regulatory limit for an 8
hour exposure. A short exposure to this concentration will not
cause serious damage, but should alert you to a possible
problem. At higher concentrations (400 ppm, for example)
anhydrous ammonia has a pungent odour that will sting and
irritate the nose, throat and eyes. Most people cannot tolerate
this and will leave the area without any permanent damage.
Anhydrous ammonia is not regarded as a fire hazard, as it is
unusual for it to explode or burn.
Risk
of Exposure:
Anhydrous ammonia is a colourless gas, but when released from
tanks in high concentrations, it looks like dense steam.
Dangerous concentrations usually occur when there is a major
rupture or leak of a tank, hose or connector. Smaller releases
can also occur, for example when one of the application tubes or
knives has been damaged.
Equipment
Safety:
It is
probable that your local Government Agencies will want to
inspect your anhydrous ammonia tanks on a regular basis and may
therefore need to be registered before use. Tanks, fittings,
hoses, couplers, connectors and machinery used for the
application of anhydrous ammonia, and which tow applicator tanks
during the application must meet strict standards
All
ammonia equipment must carry appropriate signs and have
appropriate safety markings. Anhydrous ammonia is classified by
the United nations as a “Dangerous Good” and is transported
under the EU regulations that relate to the
Transportation of Dangerous
Goods. It is also regarded as a dangerous product
and its use should be carefully supervised in the work place.
In the glossary we include appropriate MSDS data for anhydrous
ammonia.
You
should never fill a tank over 85% of its capacity and never
leave transfer operations unattended. Always be sure to relieve
pressure before disconnecting hoses or parts. When equipment is
unattended, always close valves and disconnect hoses.
Do
not use fertilizer additives in an anhydrous ammonia tank.
Mixing these chemicals may set off a dangerous chemical reaction
and cause injury. Anhydrous ammonia is not only very corrosive
to living tissue; it is corrosive to brass, copper, zinc and
many alloys. Anhydrous ammonia tanks and equipment must not be
used for any other compressed gases unless a qualified engineer
has certified the tank for that purpose.
Safe Handling:
·
If
you are considering transporting anhydrous ammonia, contact your
local Government Agency with responsibility for Highways and
Transportation to obtain the detailed local regulations that you
will need to follow.
·
Always wear the goggles and rubber gloves provided with the
equipment when handling anhydrous ammonia.
·
Certain repair and maintenance procedures may involve some
exposure to known concentrations of ammonia gas. For these
procedures a respirator can provide adequate protection. Wear
an approved respirator with cartridges suitable for ammonia.
Wearing a full-face mask is recommended, but a half-face mask
can also be worn with goggles. Do not attempt a repair or
maintenance procedure if concentrations of anhydrous ammonia
over 250 ppm (parts per million) are anticipated. The
respirator will not provide enough protection at these
concentrations. Contact your dealer instead.
·
Clean, fresh water must be available for first aid. One
container of not less than 4 gallons must be on the applicator
and another smaller one in the tractor. The operator should
carry a small squeeze bottle of water in his shirt pocket. Use
this to immediately flush eyes in the event of an accident.
·
Contact lenses should not be worn when working with anhydrous
ammonia. They can trap ammonia against the eyes and cause
blindness.
·
Work
upwind, keeping face and body clear. Concentrate on the task at
hand. Children, bystanders and pets should be kept well away.
·
Equipment should be inspected regularly and maintained in good
condition.
·
Instructions from the equipment manufacturer and dealer must be
followed.
·
Do
not use anhydrous ammonia indoors.
·
Keep
emergency numbers handy and have some means of summoning help
quickly.
·
Never
attempt field adjustments or repairs without noting wind
direction and staying upwind.
Dealing With Emergencies:
Be
alert to the smell of ammonia. The smell can warn you of a
leak. If the smell is pungent, assume the leak or rupture is
serious. In the event of a serious rupture or leak accident,
never try to handle the emergency by yourself. Quickly evacuate
upwind, wearing a respirator if it is handy. Contact your
dealer and the RCMP immediately.
First Aid:
In
the event of suspected injury, get medical help immediately and
tell them you were exposed to anhydrous ammonia.
Eyes:
Water
is the only effective first aid treatment. You must begin
flushing immediately. Seconds may save your eyesight. Carry a
small squeeze bottle of water with you at all times and use it
until you can reach the larger water containers on your
equipment. Your eyes must be held open and rinsed thoroughly
with clean water. Rinse both the eyes and linings of the
eyelids. Keep washing for at least 20 minutes. Then get help
and go to a doctor immediately. Continue flushing your eyes on
the way
Skin:
Ammonia will continue to burn as long as it remains on your
skin. Wash it off with water for at least 20 minutes. Clothing
may be frozen to the skin. Thaw the clothing by soaking with
water before trying to remove it. Do not use salves or
ointments on an ammonia burn. Seek medical assistance
immediately.
Inhalation:
Move
the victim immediately to an uncontaminated area. Keep the
victim warm and get to a hospital as soon as possible. If
breathing has stopped, begin artificial respiration immediately
and administer oxygen. Watch for signs of shock and keep the
victim at rest. Activity can worsen respiratory problems.
More
information can be found at:
http://www.labour.gov.sk.ca/safety/pamphlets/anhydrous/caution.htm
D.
Safe Storage and Handling of Ammonium Nitrate
based Fertilizers and Soil Additives
The
following information has been taken from a pamphlet developed
by the Health and Safety Executive in the UK to explain the
implications of the UK Health and Safety at Work etc Act 1974
for the safe storage and handling of ammonium nitrate in large
quantities such as might be found on a farm. The full leaflet
is available at
http://www.hse.gov.uk/pubns/indg230.pdf.
The
main use of ammonium nitrate is as a fertiliser, marketed either
as prills (small spheres) or granules. It has a melting point
of 1700C and decomposes above 2100C. It
is not in itself combustible but, as it is an oxidizing agent,
it can assist other materials to burn, even if air is excluded.
Ammonium nitrate will not explode due to the friction and impact
found in normal handling, but it can be detonated under heat and
confinement or severe shock. For example, in a fire, pools of
molten ammonium nitrate may be formed and if the molten mass
becomes confined (eg in drains, pipes, plant or machinery) it
could explode, particularly if it becomes contaminated.
In a
fire, all types of ammonium nitrate may melt and decompose with
the release of toxic fumes (mainly oxides of nitrogen) which may
be yellow or brown. Most types do not continue to decompose
once the fire has been extinguished. However, when some types
of ammonium nitrate fertilisers (cigar burners) are heated they
undergo a smouldering (self-sustaining) decomposition that can
spread throughout the mass to give substantial toxic fumes, even
when the initial heat source is removed.
The
risk of fire or explosion is greatly increased if ammonium
nitrate is mixed with combustible or incompatible materials,
such as powdered metals, alkali metals, urea, chromium or copper
salts, organic and carbonaceous materials, sulphur, nitrites,
alkalis, acids, chlorates and reducing agents (consult data
sheets to establish if a substance has reducing properties).
Fertilisers that contain 28% or less nitrogen. Compound
fertilizers form the major proportion of this group. The
straight nitrogen types are usually a mixture of ammonium
nitrate with limestone or similar inert materials. These
materials rarely present an explosion hazard.
For
ammonium nitrate and ammonium nitrate fertilisers that contain
more than 28% nitrogen, the risk of an explosion is increased by
a combination of the following:
-
heating ammonium nitrate (eg in a fire);
-
contamination;
-
serious confinement (eg in drains or enclosed parts of
equipment).
To
minimise the risk of explosion it is therefore important to take
precautions against each of these situations. In the UK, the
Fertilisers Regulations 1991, as amended, require all straight
ammonium nitrate fertiliser with more than 28% nitrogen, sold
for final use in the UK, to be packaged and meet certain quality
criteria, minimising the risk of contamination and therefore
explosion. Similar regulations will be in force in all EU
Member States.
Storage areas:
Ammonium nitrate should normally be stored in single storey,
dedicated, well-ventilated buildings that are constructed from
materials that will not burn, such as concrete, bricks or
steel. Clean the store before it is used for ammonium nitrate.
However, in some circumstances, such as where the stores are
located near to densely populated areas, it may be better to
store ammonium nitrate outside, provided it is in a secure area
away from combustible materials and sources of contamination.
Such outdoor storage can remove or reduce the risk of, for
example, fires due to electric lights and other equipment.
However, if ammonium nitrate is stored outdoors it may be
necessary to consider methods to prevent it deteriorating due to
sunlight or water (eg covering it with sheets or shrink-wrapping
and ensuring that water can run away from the storage area).
Avoid
drains, channels or pits where molten ammonium nitrate from a
fire could become confined. Where the presence of drains, etc
is unavoidable, they should be protected so that molten ammonium
nitrate cannot run into them. Locate storage away from possible
sources of heat, fire or explosion, such as oil storage, gas
pipelines, timber yards, flammable liquids, flammable solids and
combustible materials.
Arson
and faulty or damaged electrical equipment are major risk
factors for warehouse fires, so prevent unauthorised access to
the store. Ensure regular inspection and maintenance of
electrical equipment and fittings. Damage from animals can be
limited by implementing a pest control system.
Stacks:
Self-confinement of straight ammonium nitrate in large stacks
can increase the risk of a detonation of the whole stack in a
fire, so limit stacks to a maximum of 300 tonnes Keep straight
ammonium nitrate of relatively low density (ie non fertiliser
grade below 900 kg/m3-
see the label or other documents) to stacks of approximately 2 m
high and 3 m wide, but again this limit may be raised at
purpose-built stores.
To
help prevent fires and other heat sources from affecting stored
ammonium nitrate, and to allow access to stacks in an emergency,
leave a space of at least 1 m between stacks and between the
stack and the walls, roof or any electric lights or heating
pipes. Check the height of doors, beams and electrical
equipment in relation to that of any lifting equipment used,
such as fork-lift trucks.
Do
not allow ammonium nitrate, including when molten in a fire, to
come into contact with materials such as flammable liquids,
powdered metals, acids, chlorates, nitrates, zinc, copper and
its salts, oils, grease, gas cylinders and chemicals of
incompatible or unknown properties. Do not store ammonium
nitrate in the same building as such materials.
When
it is absolutely necessary to store urea and ammonium nitrate
products in the same building, keep them in such a manner that
they cannot mix with each other in any likely accident. This
can be achieved by keeping the materials in separate bays which
have walls that extend at least 1 m beyond the limit of storage
of each material.
Do
not store ammonium nitrate that contains more than 28% nitrogen
in the same stack as other products.
On
farms, separate ammonium nitrate fertiliser from hay, straw,
grain, feedstuffs, or other combustible materials by a suitable
fire break, such as a distance of at least 5 m or a barrier of
inert material of at least 1.5 m (eg one pallet) width.
General precautions:
For
ease of movement and stability of the stacks keep 50 kg bags
palletised. To prevent spillage and contamination make sure
that the bags have been completely sealed on filling, are made
of a material that is impermeable to water or oil, and are
strong enough to withstand damage during normal storage,
handling and conveyance. Paper packaging alone is therefore
unsuitable. It is recommended that 50 kg bags have microvents
to avoid ballooning and consequent instability in stacks.
Where
wooden pallets are used check that they are not damaged or
significantly contaminated. Do not store unused pallets in, or
against the walls of, the store because of the increased risk of
fire affecting the ammonium nitrate. Where it is necessary to
keep the pallets in the store, separate them from the ammonium
nitrate by a suitable fire break or partition.
Prohibit smoking in all storage areas and display prominent NO
SMOKING notices.
Keep
vehicles, fork-lift trucks and mechanical shovels clean and well
maintained to prevent ammonium nitrate coming into contact with
fuel, oil or grease. It is recommended that mobile equipment is
fitted with suitable fire extinguishers of adequate capacity to
deal with a fire on the vehicle. Do not leave such equipment
running while unattended or store it in the stortage area unless
separated from the ammonium nitrate by a suitable fire break,
preferably in a clearly marked, dedicated area.
Housekeeping: The following precautions are also essential:
-
Store filled bags and intermediate bulk containers (IBCs) in
stable stacks.
-
Clear spillage up promptly.
-
Do
not use organic materials such as sawdust as an aid to
cleaning floors.
-
Put
damaged bags into overpacks, ie a secondary bag of sound
construction that will prevent further spillage.
-
Promptly and safely dispose of contaminated products. Small
amounts may be spread thinly on open ground or washed away as
permissible, but not into water courses or drains.
-
Do
not allow pallets, ropes, covers, or other equipment to become
impregnated with ammonium nitrate.
-
Keep walls, floors and equipment clean.
-
Locate electrical equipment where it cannot come into contact
with the stored materials.
-
Avoid hollow sections in equipment, or where unavoidable wash
them regularly (away from the storage area) to prevent any
build-up of ammonium nitrate.
-
Ensure that bags of ammonium nitrate have been removed from
the immediate area and contaminated items have been thoroughly
washed to remove ammonium nitrate before allowing any
maintenance that involves heat, such as welding or cutting.
Apart from the risk of explosion in confined areas there is
also a risk of toxic fumes being produced.
Fire precautions:
Inform the local fire authority that ammonium nitrate is stored
and agree with them the arrangements for giving early warning of
a fire, providing suitable access to the site and ensuring that
an adequate supply of water is available, or can be made
available, to tackle an incident.
Note: Where a site
contains 25 tonnes or more of dangerous substances, the
Dangerous Substances (Notification and Marking of Sites)
Regulations 1990 in the UK require the person in control of the
site to notify the fire authority and the enforcing authority of
certain details. Similar rules are likely to apply in all
Member States.
Employees need to be trained and practised in the actions to
take in a fire. This includes using portable fire-fighting
equipment to tackle any fire in its early stages. Portable
water fire extinguishers or fire hose reels are appropriate
where ammonium nitrate is, or might be, involved. To enable
employees to deal with such incidents, they need to receive
specific training to ensure that they do not put themselves at
risk of breathing fumes from decomposing ammonium nitrate.
The
effects of the inhalation of these fumes may be delayed so if
anyone has, or is suspected of having, inhaled such fumes,
remove them to a safe shaded area where they should be kept warm
and rested, ideally lying down. Seek immediate medical help.
Additional safeguards may be necessary at some sites where there
are large quantities of ammonium nitrate which, due to explosion
or fumes in a fire, might affect neighbouring buildings or plant
or pose a significant off-site risk. These safeguards may
include measures to ensure that the fire brigade is called
quickly, for example an automatic fire detection system or
continuous supervisory staffing by workers who have ready access
to a telephone. Consider the need to install a fixed water
deluge system as well, which may also help limit the potential
for environmental damage by contaminated water from subsequent
fire-fighting. Further advice on the control of fire-water
run-off is given in EH 70.
Bulk products:
All ammonium nitrate fertilisers with more than 28% nitrogen by
weight, sold for final use in the UK, must be packaged.
However, bulk products could be stored at, for example bagging
plants or premises where they are blended with other
ingredients. There is a greater risk of an unpackaged (bulk)
product becoming contaminated than there is with a packaged
product. Therefore it is essential that precautions are taken
to minimise the risk of contamination, especially with
combustible or incompatible materials. The advice already given
also applies to bulk products (except for the paragraphs on
palletised product which are not relevant). The following
advice is additional.
Only
store bulk ammonium nitrate inside buildings constructed as
described for packaged products, or in silos made from materials
that do not readily ignite, such as glass fibre reinforced
plastic. Situate such silos at least 10 m from combustible
materials. Due to the corrosive nature of ammonium nitrate,
avoid using galvanized items such as sheeting, joints and
girders.
Whenever possible, only use the buildings for ammonium nitrate
and ingredients used in ammonium nitrate fertiliser blends.
When the buildings are not being used for ammonium nitrate
fertilisers, thoroughly clean them before any other product is
introduced.
The
building may be subdivided into storage bays of convenient shape
and dimensions and constructed of a material that does not burn,
preferably concrete. To prevent cross contamination:
-
clearly label the bays to indicate what they are intended for;
-
do
not store other products in the same bay;
-
clean bays regularly;
-
inspect bays for contamination before new batches are added;
and
-
clean any mechanical handling equipment before and after it is
used for other products.
Ideally, fertilisers should be taken in and out of a building by
a conveyor system. Equipment used in the handling of ammonium
nitrate, such as conveyor belts, should be made of material that
does not readily ignite or burn. Keep the equipment well
maintained to avoid potential heat sources and contamination.
Where
a mechanical shovel is used to feed the conveyor or load
vehicles it should preferably be kept in the building - in a
clearly marked, dedicated area which is separated from the
storage area by a suitable fire break - except when it has to be
maintained or repaired. Where it is not reasonably practicable
to use a conveyor system, and it is necessary to introduce a
road vehicle into the store, it is important that the vehicle is
inspected for oil and fuel leaks and the load compartment or the
ammonium nitrate carried does not become contaminated. Good
maintenance of vehicles is essential to prevent contamination.
To
minimise the risk of contamination, keep the doors to the store
closed as much as possible and only allow access to authorised
people.
Keep
any passage next to the storage area clean, and remove any
spillage promptly, place it in a dedicated area and dispose of
it as soon as possible. Do not allow fertiliser to become
compacted into the floor of the passage or bays where it can
become contaminated with spilled oil, etc.
Decomposition could occur if heaters are positioned too near to
ammonium nitrate or if dust deposits are allowed to accumulate
on steam pipes or other heating devices. Do not use direct
electrical heaters in ammonium nitrate stores.
In
unheated buildings, cover ammonium nitrate with a waterproof
sheet to minimise the pick-up of moisture, which could lead to
caking of the product and an increased susceptibility to
explosion in a fire.
Ensure that light fittings are robust, made of material that
does not readily burn and constructed or positioned so that
ammonium nitrate dust cannot penetrate them. Locate main
electrical switches, fuses, etc outside the storage area to
minimise the risk of fire. Do not locate local switches where
they could lead to a fire in the store or contact stored
ammonium nitrate.
It is
important in harbour areas for loading and unloading facilities
from ship to shore to be designed to avoid contamination.
Loading and unloading during adverse weather such as rain, snow,
or hail are not advisable because of the risk of caking.
Premises where ammonium nitrate is stored may be subject to
specific national regulations, depending on the quantity stored.
The
following terms are used to describe the different types of
ammonium nitrate fertiliser The type can be identified in
practice from information on the label or data sheets supplied
with the product:
-
Straight ammonium nitrate
fertiliser contains ammonium nitrate to provide the essential
element nitrogen, although it may also contain fillers such as
ground limestone, calcium sulphate, ground dolomite, magnesium
sulphate or kieserite.
-
Compound
fertiliser contains ammonium nitrate mixed with potash and/or
phosphate to supply the essential elements nitrogen, potassium
and phosphorus. They are sometimes referred to as NPK
fertilisers.
-
EEC
fertiliser is
fertiliser that meets certain quality, packaging and labeling
requirements specified in the fertiliser Regulations 1991, as
amended.
-
EEC grade straight ammonium nitrate
fertiliser is
straight ammonium nitrate fertiliser that meets certain
quality specifications (based on Annex 1 of Directive
80/876/EEC) of the fertiliser Regulations 1991. The
designation 'EEC fertiliser ' therefore distinguishes them as
posing less of an explosion hazard than similar products. The
consequence is that larger quantities may be stored before
certain regulations apply (see the section on specific
legislation, page 10).
-
Cigar burners
are
ammonium nitrate
fertilizers which, if they are in a fire, can
sustain a decomposition even once the fire has been
extinguished. They are normally compound fertilisers that
contain between 5% to 25% nitrogen from ammonium nitrate, up
to 20% phosphate (as P2O5)
and chloride (which may only be present as a small
percentage). However, a fertiliser that meets this
description is not necessarily a cigar burner. Currently, none
are manufactured in the UK, but you should consult the
manufacturer or supplier to establish whether their products
are cigar burners.
E.
Safe Storage and Handling of Urea based
Fertilizers and Soil Additives
This
information is part of a more detailed explanation of urea
fertilizers and was extracted from:
http://www.extension.umn.edu/distribution/cropsystems/DC0636.html
In
the past decade urea has surpassed and nearly replaced ammonium
nitrate as a fertilizer. This has brought about new questions on
urea and its use.
It is a
white, crystalline solid containing 46% nitrogen, and widely
used in the agricultural industry as an animal feed additive and
fertilizer.
Commercially, urea fertilizer can be purchased as prills, or as
a granulated material. In the past, it was usually produced by
dropping liquid urea from a "prilling tower" while drying the
product. The prills formed a smaller and softer substance than
other materials commonly used in fertilizer blends. Today,
though, considerable amounts of urea are manufactured as
granules. Granules are larger, harder, and more resistant to
moisture than prills. As a result, granulated urea has become a
more suitable material for fertilizer blends.
Advantages of Fertilizer Urea
-
Urea can be applied to soil as a solid or solution or to
certain crops as a foliar spray.
-
Urea usage involves little or no fire or explosion hazard.
-
Urea's high analysis, 46% N, helps reduce handling, storage
and transportation costs over other dry N forms.
-
Urea manufacture releases few pollutants to the environment.
-
Urea, when properly applied, results in crop yield increases
equal to other forms of nitrogen.
Urea
Storage:
Urea is neither combustible nor explosive. It can be stored
safely with no loss of quality under normal circumstances.
Small or fast-moving augers should not be used to move granular
urea. Urea particles are generally soft and abrasion can break
the granules. Belt conveyers should be used whenever possible.
However, urea should not be stored with ammonium nitrate. These
materials, when in contact, rapidly absorb water when the
relative humidity is above 18%. The table below indicates the
relative humidity at which urea and ammonium nitrate absorb
moisture from the air.
Material |
CRH% |
|
Urea |
75.2 |
|
Ammonium Nitrate (A.N.) |
59.4 |
|
Urea + ammonium nitrate |
18.1 |
Critical relative humidities (CRH) of urea, ammonium nitrate,
and a mixture of the two
F.
Equipment maintenance: Fertilizer applicators
The following information has been adapted from the American
website:
http://www.ipm.iastate.edu/ipm/icm/2002/2-18-2002/fertapplicators.html
Liquid fertilizer application equipment:
The
primary maintenance consideration for liquid fertilizer
application equipment is the relatively high application volumes
required. For example, an application of liquid nitrogen of 150
lb/acre using UAN solutions requires 50 gal/acre, adding up to
2,000 gallons for a 40-acre field. Older centrifugal or roller
pumps are not good choices to deliver high-capacity flow. Pump
capacities of less than 40 gallons per minute and 1/2-inch
distribution hoses on applicators are probably inadequate for
larger sprayers. Check the pump closely for wear, regardless of
its capacity, because suspension materials used for liquid
fertilizers can accelerate wear and tear.
Look
the sprayer over closely, paying attention to hoses and pipes.
They need to be clean and free of clogs, kinks, and leaks.
Consider Viton seals in check valves for heavy use to avoid
rapid seal deterioration. When you do get to the field, check
for even application. And don't forget that the equipment should
be rinsed and cleaned at the end of each day.
Dry granular fertilizer application equipment:
Spinners can vary between spreading equipment models, but the
checklist for obtaining a uniform pattern with dry granular
fertilizer equipment includes inspection of the gate opening,
divider (between two spinners) position, delivery point to the
spinner, spinner speed, and vane-blade angle on the spinner. On
pneumatic spreaders, check for uniform flow to each distribution
tube and proper adjustment of trim tabs and deflectors at the
exits of the tubes
When
applying granular fertilizer, wait for low winds and make sure
the swath pattern is accurate. The physical properties of dry
fertilizer material can be inconsistent, so it is important to
ensure even distribution within the swath. When you are in the
field, do a pattern check by laying out several pans
perpendicular to the direction of travel of the spreader.
Avoid
using granules of varying size in the same application. Larger
granules tend to roll off the "cone" when loading. Make several
smaller cones as you load to avoid problems.
Anhydrous ammonia application equipment:
The
nature of anhydrous ammonia (a high-pressure liquid converted to
a liquid-gas mixture as pressure drops while traveling to the
knife outlet) makes safety a primary consideration when looking
at equipment.
Check
the condition of the knives to make sure they can penetrate the
soil adequately and distribute anhydrous ammonia evenly, and
remember to test them in the field, adapting spring pressure to
current conditions, such as soil type, soil moisture, and soil
compaction.
Make
sure that hoses and pipes are clean and free of clogs, kinks,
and leaks. Iowa Sate University researchers recommend connecting
hoses from adjacent applicator shanks to different regions
around the manifold outlet ring to improve distribution across
the applicator's swath. Also, the length of each hose from the
distribution manifold to each injection knife should be equal.
Coil hoses that attach to knives near the manifold and secure
them horizontally.
When
connecting hoses during application season, avoid introducing
ammonia into the line until necessary. Make all the connections,
tighten the bleeder valves, and then open the valves starting at
the furthest downstream valve and work upstream, opening the
valve at the tank that releases ammonia into the hose last. When
disconnecting hoses, start closing valves at the upstream end
and work toward the downstream end.
As you
work with anhydrous ammonia this spring, stay upwind when
operating valves. Also, keep a 5-gallon water supply available
and a 6-ounce plastic squeeze bottle in your pocket for
immediate treatment of accidental exposures. Be aware of
volatilization of nitrogen (N). Losing N to volatilization is an
avoidable expense. Shallow (2-4-inch) incorporation of liquid
and dry granular N urea-containing fertilizers can reduce
potential volatilization loss. Anhydrous ammonia should be
injected deeply enough to avoid losses. If you smell or see
excess vapor escaping, reset the covering discs or "beaver tail"
tabs.
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