livestock
livestock
a n i m a l s c i en ce
j u ly 2 012
Manure Management for Horse Owners
Erin Cortus | SDSU Assistant Professor & Environmental Quality Engineer Rebecca Bott | SDSU Extension Equine Specialist
Horse owners learn quickly through experience that a
horse can produce an enormous amount of manure.
On average, a 1,000-pound horse can produce upwards of 50 pounds of manure each day, nearly 9 tons
yearly. This manure not only takes up a large amount
of space, but if left un-managed, manure components
can taint water and air, create unbalanced and less
productive pastures, and increase risks of internal
parasites. Potential long-term impacts of poor manure
management are horse health impacts, reduced productivity of pasture land (this may mean having to purchase more horse feed), pollution of water and air and
reduced land value. However, manure is an important
plant fertilizer and should be viewed as an important
resource in that regard.
Stewardship means taking responsibility for one’s
choices. The goal of this iGrow Solution is to demonstrate how horse owners can practice environmental
stewardship through (1) understanding the environmental risks associated with manure; and (2) understanding
the best management practices for manure management on a small farm to address these environmental
risks and effectively utilize the nutrients in the manure.
Taking responsibility for manure management benefits
everybody, including horses, pasture land, environment, and neighbor relations.
What are the Environmental Risks
associated with Manure?
Manure contains valuable nutrients like nitrogen and
phosphorus, as well as organic matter, which are
beneficial for crops and other vegetation when properly applied to the land. However, horse owners, like
all other livestock owners, should also be aware that
these components of manure can degrade water and
air quality when they are transported away from where
they are intended to be stored or utilized as fertilizer.
Manure and Water Quality Risks
The common contaminants from manure are nitrogen
(in the form of ammonia and nitrates), phosphorus,
pathogens and organic matter. When these nutrients
contaminate a water source they can have very serious
health implications not only for the environment, but
also for for our horses and other animals and our families (Table 1).
Under most circumstances, manure contaminants travel via indirect routes to water bodies. Surface runoff
occurs when rainfall or other water flows over a land
area or manure pile, picking up soil and manure particles and depositing them away from the source, often
in a water body. Surface runoff is the primary transport
mechanism for the common manure contaminants
to move away from either a manure storage area or
horse pasture. As water moves down through the soil,
the soil will filter a majority of manure contaminants.
However, nitrate nitrogen can move with the water and
travel through the soil to ground water. This process is
called leaching. The groundwater may later be pumped
up and used for drinking water or eventually feed into
surface waters. Manure contaminants can also infiltrate into the soil through large cracks or move along
well casings to the ground water.
Finally, manure can release ammonia nitrogen into the
air as a gas to be deposited elsewhere, including on
water bodies.
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Ta b l e 1. C o m m o n man u r e co n t amin an t s, t h e ir p r e d o mi nant envi ronment al ri sk, and thei r most common pathway to water.
Ad a p t e d f r o m Ko e lsch (2 0 0 3 ).
Potential Pollut ant
Envi r on me n t a l R i s k
Mo s t C o mmo n Pa t h wa y t o Wa t e r
Hig h n itrate l evel s can cause bl ue baby
syn d r o me, whi ch i s most l i kel y to harm
N i t r a t e - N i t ro g e n
in fan t s and pregnant women due to
oxyg e n depri vati on. The st andard for
d r in kin g water i s 10 mg/L^-1.
A m m o n i a - N i t ro ge n
Phosphorus
Pa t h o g e n s
parti cl es that move through the s oi l . If the
water and ni trate i s not t aken u p a nd us ed
by a pl ant, i t can move or l each further
down through the soi l to ground wa ter tha t
feeds a wel l or surface water bo dy.
Ammo n i um-N i n water can be toxi c to
Ammoni um-N can move from th e l a nd i n
f ish . Toxi ci t y depends on the temperature
surface water runoff. It i s hi ghly vol a ti l e,
an d p H of cont ami nated water. Fi sh are
meani ng i t can transfer from wa ter to a i r i n
su sce p t i bl e when l evel s exceed 2 mg L-1.
the form of gas. Once i t i s i n the a i r i t c a n
Th e lo ss of fi sh harms the bi odi versi t y of
be redeposi ted i n another l ocati on away
a wat e r body.
from the source.
P h o sp h orus, together wi th ni trogen can
Phosphorus i s mai nl y excreted in s ol i d
cau se excessi ve al gae growth i n l akes
manure and st ays bound to sol i d m a teri a l .
an d e stuari es. Thi s, i n turn l i mi ts aquati c
Therefore, phosphorus tends to bi nd to
p lan t g r owth, l eadi ng to reduced vari et y
sol i d parti cl es and move from the s i te of
in p lan t s and other aquati c organi sms.
manure deposi ti on i n surface wa ter runoff
Th is p r ocess i s cal l ed eutrophi cati on.
or wi th soi l erosi on.
Th e r e are numerous human and horse
Pathogens are most l i kel y to travel a c ros s
h e alt h r isks associ ated wi th di fferent
l and i n surface water runoff to wa ter
b act e r ia, vi ruses, and protozoa that may
bodi es, or be deposi ted di rectl y through
b e p r e sent i n fresh horse manure.
ani mal wadi ng i nto l akes and strea m s .
Or g an ic matter consumes the oxygen i n
Organic solids
N i trate compounds att ach to wa ter
wat e r as i t breaks down. Thi s depl etes
t h e oxygen suppl y for other speci es, l i ke
f ish , in the water.
Organi c sol i ds are most l i kel y to be
transported to surface water i n s urfa c e
water runoff.
Manure and Air Quality Risks
Gases, dust and odor released from manure can degrade the air quality in and around a farm. For small
farms, odor is likely to raise the largest stink. Odor is a
combination of many gases, many in very low concentrations. The risk for gas and odor release is greatest
when there is exposed wet manure, with warm temperatures and high airflow. Exposed wet manure also
provides a breeding ground for flies. The more concentrated and large manure storage areas will produce
higher levels of odors. Horses that are kept indoors
in poorly or inadequately ventilated buildings are also
at risk for respiratory distress from the ammonia in
urine. Barns that are properly ventilated will reduce the
buildup of ammonia in the air, thus creating a healthier
environment for your horse and you.
and measurements of your property, identifying water
sources, direction of water flow after a rain, neighbors,
and prominent wind directions can help you to identify
potential problem areas and minimize risks.
Assessing Environmental Risks
It’s a fact of life - if you have a horse on your property
there will be manure. If manure is stored in an area
away from large amounts of water runoff or ground
water access points, the environmental risks are lower
- but what are appropriate distances? Taking stock
Step 1: Sketch a layout for your farm and identify areas
of interest (see Figure 1 for an example layout).
•
Draw the farm, using simple circles to show main
components or use an aerial/satellite photo available from numerous online map programs (draw in
any changes to the farm since photo was taken)
•
Identify where manure is located, stored and/or
applied. This includes pastures, storage areas and
fields.
•
Identify water bodies (i.e. streams, lakes, rivers,
ditches) and water sources (i.e. wells) within 200 ft
of the farm.
•
Identify neighbors or businesses within 500 ft of
the farm.
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Step 2: Show water and air movement, and separation
distances on the layout with arrows.
•
When it rains, what direction does water tend to
flow away from the manure locations?
•
What direction does water flow in the water bodies or ditches?
•
What is the common wind direction in the summer?
•
What is the depth of any drinking water well? This
is typically noted on a well log, and this indicates
the depth of a usable water supply.
•
Calculate distances between manure storage/application areas with water bodies, well casings and
neighbors.
Step 3: Identify water and air quality risk areas.
•
Using Table 2, go through each column and circle
the square(s) that apply to your pasture or manure
stockpiling/storage area. If you do not use either,
leave this table blank. Once you have finished,
identify any circles in the high or moderately high
risk rows.
•
Using Table 3, circle the squares that apply to your
exercise area. If you do not have one, leave this
table blank. Once you have finished, identify any
circles in the high or moderately high risk rows.
Step 4: Evaluate best management practices that can
reduce water and air quality risks for your farm. Consider the environmental benefit, cost, time and energy
requirements for each practice.
Ta b l e 2 . R i s k a s s e ssme n t fo r wat e r an d air q u alit y cont ami nati on by nutri ents, pathogens and organi c sol i ds from pastures a nd
s t o ck p i l e d m a n u r e . (ad ap t e d f r o m Far m-A-Syst , Wo r ksheet 7)
Pas t ur e
Pas t u re o r
S t o ck p i l e d
m an u re o r
Com p o s t p i l e s
Di s t anc e t o
wat er body
Loc at i o n re l a t i v e
t o d ri n k i n g
wat e r w e l l
Risk
S t o ck p i l e d ma n u re o r C o mp o s t p i l e s
Ru n o ff c o n t ro l
Ma n u re s u rf a c e
ch a ra c t e ri s t i c s
Re l a t i o nship t o
n e i g hbor s
Pi l e covered wi th
5 0 0 ft o r g r e at e r,
L ow
w it h a ru n o ff
co n t r o l syst e m*
Dow n sl ope from
wel l
straw or t arp, on a
Manure surface
50 0 ft o r grea ter;
concrete pad wi th
covered wi th straw
or downw i nd duri ng
curbs, gutters and
or other materi al
warm s ea s on
settl i ng basi n
On a concrete pad
Mo d e ra te l y L ow
15 0 0 ft o r g r e at e r,
On level ground (no
n o ru n o ff co n t r o l
slo p e ), more than
syst e m
20 0 ft
wi th curbs, gutters
Shelterbel t
and wel l -mai nt ai ned
downwi nd from
veget ati on
manure s ourc e
surroundi ng storage
area**
St acked on hi gh
ground i n the fi el d
L ive st o ck p r eve n t e d
Mo d e ra te l y H i g h
f r o m e n t e r in g
On level ground,
or i n an earthen
Manure surface
ad jace n t wat e r b o d y
le ss than 20 0 ft
yard, fi ne-textured
general l y dr y
soi l s, water t abl e
by fe n cin g
deeper than 20 ft
Stacked on high
S t r e am f low s
High
through the
Up slo p e from wel l ,
p astu r e ; live st o ck
d ist an ce l ess than
n o t fe n ce d f r o m
10 0 ft
wat e r b o d y
ground in the field
or in an earthen
Large, exposed and
yard, coarse-
wet manure surface
textured soils, water
Less tha n 50 ft,
upwi nd d uri ng wa rm
sea s on
table within 20 ft
* A ru n o ff c o n t r o l syst e m is t h e u se o f o n e o r mo r e management practi ces to prevent water pol l uti on; management prac ti c es c a n
in c l u d e d i ve r s i o n of ru n o ff f r o m t h e yar d , r o o f ru n o ff systems, yard shapi ng , settl i ng basi ns, fi l ter stri ps and/or buffer area s .
** D i m e n s i o n s o f ve g e t at ive f ilt e r st r ip s/b u ffe r s d e pend on the characteri sti cs of the manure storage area.
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Ta bl e 3 . R i s k a s s e s s me n t fo r wat e r an d air q u alit y co n t ami nati on by nutri ents, pathogens and organi c sol i ds from exerci se l ots ,
ba rnya r d s , b a r n s , o r ot h e r h ar d , e ar t h e n su r face s w it h l i ttl e veget ati on where horses spend a l ot of ti me. (adapted from Fa rm -A -Sys t,
Work s h e e t 8 a n d 8 A )
Risk
Dista nc e
to wa t er
body
Loc at i on
r el at i ve t o
dr i nk i ng
wat er w el l
S l ope
Clean
wa t e r
diversion*
Lo t ru n o ff
Ya rd
cleaning
&
s c ra p i n g
Ma n u re
application
Anima l
c o nce nt r a t ion
( f or e x e r cise
lot only )
Based on
5 0 0 ft o r
g r e a t e r, w it h
L ow
a ru no ff
control
2 -7 % slo p e,
A l l upsl ope
Dow n slo p e
ru n o ff
and roof
f r o m we ll
co n t r o l
water
syst e m
di verted
s ys te m
a nutri ent
N o yard runoff
N o yard
management
(ei ther barn or
(ani mal s
pl an (i ncl udi ng
roofed area)
confi ned)
regul ar soi l
C onfi ned to ba rn
or on pa s ture
and manure
tests)
A l l runoff
15 0 0 ft o r
M od e ra te l y
L ow
g r e at e r,
n o ru n o ff
c o n tr o l
s ys t e m
On leve l
2 -7 % slo p e,
Most
ground,
n o ru n o ff
upsl ope and
mo r e t h an
co n t r o l
roof water
2 0 0 ft
syst e m
di verted
col l ected;
Sol i ds
separated;
Water
Once per
week
Manure
i ncorporated
i nto soi l
di rected onto
M ore tha n
250 0 s qua re ft
per a ni m a l ; N o
pa s ture
fi l ter stri p
L i ve s t o ck
M od e ra te l y
High
fe n ce d
On leve l
away f r o m
g r o u n d , le ss
a d j a ce n t
t h an 2 0 0 ft
7-14 % slo pe
wa t e r b o d y
S t r e am
High
f l ows
Up slo p e
No slo p e ,
t h r o u gh lo t ;
f r o m we ll,
o r slo p e
l i ve s t o ck n o t
le ss t h an
g r e at e r t h an
fe n c e d f r o m
10 0 ft
15%
wa t e r b o d y
N o upsl ope
Most of
water
l ot runoff
di verted;
col l ected
Some roof
from curbed
Once per
water
l ot; Some
month
col l ected
sol i ds
and
removed; N o
redi rected
fi l ter stri p
Al l upsl ope
and roof
water runs
through the
Lot runoff
uncontrol l ed
yard
Rarel y
Manure
appl i ed to
sl oped l and.
M ore tha n
150 0 s qua re ft
per a ni m a l ; N o
pa s ture
Manure
Les s tha n 10 0 0
appl i ed to
s qua re ft per
sl oped and
a ni m a l ; N o
frozen l and.
pa s ture
* C l e a n wa t e r ( i . e . r ain t h at falls o n a r o o f o r u p lan d o f the ani mal /manure area) shoul d be di verted to mi ni mi ze the tot al am ount of
runo ff t o c o n t r o l a n d h an d le .
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F i g u re 1 : E xamp le far m layo u t fo r a smal l farm wi th three horses. Propert y l i ne i s shown as a dashed
l i n e . Man u r e st o r ag e an d an imal u se areas are shown i n bl ue.
What are the Best Management Practices
for Small Farm Manure Management?
Feeding the Horse
Manure composition starts with the horse’s diet. Selecting and balancing feed ingredients to meet, not
exceed, a horse’s needs is critical. The nutritional
requirements of a horse depend on their age, size, activity, and other physiological parameters such as lactation or pregnancy. Many horses are fed in excess of
their requirements. Similarly to humans, excess intake
can put horses at risk for a variety of health problems.
Obesity can lead to a variety of metabolic disorders,
and excess weight or body condition places more
strain on the joints of a horse. Furthermore, as a horse
eats more they will have to drink more water. Adequate access to clean, fresh water will help to promote
normal digestion and gut health. As a result, the urine
and manure output of that horse increases, putting
further burden on the environment. Excess nutrients
such as phosphorus and nitrogen that are not needed
by the horse will be plentiful in the urine and manure.
Research to determine appropriate feed requirements
for horses is ongoing, but some very good information to estimate their needs is available. Work with a
nutritionist or Extension Specialist who is aware of the
current recommended feeding guidelines to create a
nutrition plan that is optimal for your horse and the environment.
Managing Manure in Pastures
With a pasture-based system, manure management
goes hand-in-hand with providing water of good quality
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and source and managing the land for optimum condition of forages. The risk for odors is low, provided the
manure does not accumulate in a small, concentrated
area and is allowed to dry out. The following are some
examples of best management strategies for common
situations.
Situation: When horses reside in pastures, they
are selective in choosing grassy areas from which to
eat, and others in which to roll and defecate. These behaviors can lead to an uneven appearance of land with
“mowed” areas where horses have eaten and taller
areas where grasses grow up around manure. The
overall mass of the fecal material is greatly reduced
by the loss of water through natural weathering over
time, but the nutrients and organic matter take longer
to decompose. The nutrients in the manure can be
absorbed into the soil where the manure is deposited,
but can also be carried away by rainfall or runoff.
BMP: This uneven distribution of manure can be
corrected in part by harrowing/dragging pastures to
evenly disperse the manure. Harrowing/dragging a
pasture is most effective immediately after removing
horses. This way, the dispersed manure has a longer
exposure period to UV light and natural weathering,
which helps reduce the risk of spreading pathogens.
Situation: Nutrients and solid matter from manure or soil can be picked up by rain water and runoff
from the pasture, moving towards a water source.
BMP: Grass and other vegetation are a great filter
for preventing contaminants in water and soil runoff
from reaching other water sources. Vegetative buffer strips physically slow down the water movement,
allowing time for nutrients and solids to settle out.
These nutrients are often absorbed and utilized by the
vegetation. The necessary dimensions of the buffer
strip depend on the slope of the land, type of vegetation and soil characteristics.
pond bank and further contribute to water quality degradation in the stream.
BMP: If possible, fence horses off of streams,
ponds, or other water sources in the horse pastures
and provide an alternative drinking source in-land. If an
in-land drinking source is not available, consider the
following practices:
•
Provide access points to the water that has been
stabilized with rock, concrete or similar
•
Allow rest time for the water bank through rotational grazing
•
Provide shade away from the water source to limit
horse activity in the area to drinking
Managing Manure in a Collection or
Stockpiling System
In a collection-based system the manure is collected
from where it is deposited by a horse and used elsewhere. This can be from lots, pens, small paddocks,
stalls, corrals, trailers, or any other confinement areas
where horses defecate. The frequency that manure
is collected depends on many factors, including the
size of the area, availability of labor, and use of the
area. For example, a horse stall should be cleaned of
manure at least once daily to maintain an environment
that is healthy for the horse. In a larger area, such as a
paddock or large run, manure might be collected every
few days. If manure is piled, this is referred to as stockpiling. Alternatively, collected manure can be treated
(see Composting Systems) or land-applied (see LandApplication). If a manure stockpile presents a moderate
to high risk to water or air quality, one solution is to
consider moving the pile to an area where the risk of is
lower.
Situation: When manure is stockpiled, manure
pollutants can move from the stockpile when rainfall or
other water falls on the pile and runs off.
Situation: When horses access a stream or other
water body for water, there will be some direct manure
deposition in or adjacent to the water source. In addition, horse play and trampling can erode the stream or
BMP: Storage sites should be distanced from any
wells or water sources to reduce the risk of water
contamination by runoff. You can create a containing-
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area with solid floors and sides out of a material such
a concrete to prevent nutrient runoff or leaching. With
or without a constructed storage area, the runoff that
does occur should be either collected or directed over
a vegetated area (refer to vegetative buffer strips discussed in Pasture Systems).
Situation: Rainfall or other water, especially if the
stockpile is in the path of runoff from an uphill area,
adds to the amount of manure that must be managed,
and can make a muddy mess.
BMP: Reduce the amount of rain water that falls
directly, or indirectly, in the collection area. Clean water
diversions including roofs, rain gutters, and berms can
be used to keep fresh water separate from the manure
collection areas.
Situation: Manure nutrients like nitrate-nitrogen
can move from the manure down through the soil under the stockpile.
BMP: The stockpile should be located in an easily
accessible location with a solid or low-permeable floor
on a low-grade slope that prevents water from pooling around the pile. A solid floor helps prevent nutrient
leaching through the soil and makes manure removal
easier.
Situation: An uncovered stockpile will release
some gases and odor. The amount of ammonia and
odor release will be higher during warmer weather.
BMP: The best storage locations have taken prominent wind directions and aesthetics into consideration
to foster good relationships with neighbors. Simple
straw covers can reduce the exposed surface area and
reduce odor and gas emission; however, additional
straw will add to the amount of manure mass that
must be handled. Trees downwind of the pile can help
dilute the odorous air with cleaner air, and can also
shield the pile from eyesight.
Composting Horse Manure
Composting is a manure “treatment” option for horse
owners that can be applied to all or some of the ma-
nure. There is a misperception that piling manure is
“composting”. Composting is an active process that
requires attention to details including moisture, airflow,
and temperature. Consult a composting handbook
(such as “Horse Manure Management: A Guide for
Bay Area Horse Keepers” indicated in the reference
list) for more detailed design and management information.
Through composting, micro-organisms help break
down the manure and other material to form a soil-like
substance called compost. Careful management helps
this process proceed efficiently and produces an organic end-product free of parasites, E. Coli, and weed
seeds that can be applied to gardens and pastures.
Horse manure, combined with bedding is often the
ideal mixture of carbon and nitrogen for feeding the microorganisms, making this treatment technique easier
for horse owners compared to other species. Despite
these benefits, compost management can be time and
labor intensive. The following section provides basic
information and considerations for composting manure
on a horse farm.
Location
When selecting a site, consider the proximity of the
pile to either the manure source or the application land,
and the availability of water. The compost pile should
be situated in a well-drained area, preferably with a
2-4% slope, as far from any water sources as possible,
and preferably under cover and out of view from neighbors and the public. A cover or roofed area allows for
better moisture control compared to a pile exposed to
the elements. Compost can be highly combustible and
should be kept away from horse pens or stalls.
Size and Construction
The size and shape of a compost pile depends on the
amount of material to be composted, how often new
material is added, and where the pile is located. If a
pile is too large it may be difficult to maintain airflow
and moisture evenly throughout the pile. If it is too
small, temperatures will likely not elevate to proper
temperatures. Compost piles/bins for horse manure
need to be at least 3 feet squared in area, and more
generally are 4 feet squared and 3-5 feet in height.
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Concrete or wood flooring and sides are commonly
used. It is generally beneficial to have two or more
piles/bins to store manure at various stages in the
compost process. You do not want to mix fresh manure with a pile of compost that is nearly complete because you run the risk of introducing new pathogens to
an already pathogen-free pile. Check with your county
before starting construction to see if you need a permit
to compost.
Moisture, Temperature, and Air Flow
Composting requires careful management of pile
temperature, moisture, and material to be efficient
and effective. The compost pile is essentially a living
organism during its “active stage”. Microbes are a key
factor because they are responsible for breaking down
the manure. Just like horses, these microbes are most
efficient when their food, water and air requirements
are met. The microbe food is a balance of carbon and
nitrogen found in the fecal material, in bedding, and any
other compost material such as leaves. The ideal balance of carbon to nitrogen is near 30:1 (30 parts carbon to 1 part nitrogen) and is often found in compost
piles containing horse manure with some bedding.
Water is important because it helps microbes move
through the compost and aids with food digestion. Too
much water can block air movement through a pile,
while too little water slows down microbial activity. A
rule of thumb is to maintain a moisture level between
40 and 60%. If a handful of compost is moist to the
touch, without losing water when squeezed, it is in this
ideal range. You may need to add water to the pile to
maintain the ideal range, especially during hot or dry
weather. Infrequent monitoring will lead to a pile that
goes through dry and wet spills which may extend the
length of time necessary for the compost to mature.
Air movement helps remove heat and moisture from
the pile. A lack of oxygen leads to anaerobic conditions that produce foul odors and incomplete composting. Adding wood chips or drain tiles to the floor will
enhance air flow to the bottom of the pile. Similarly, it
may be beneficial to add thin layers of leaves or other
organic material between layers of manure to help increase airflow.
When the pile is first constructed, it will heat up as
microbes eat the organic material. Temperature is the
best indicator of active composting. Keeping temperatures in the optimum range ensures destruction
of parasites and pathogens. A temperature range of
110 to 150˚F, measured in multiple spots towards the
center depth is considered ideal. A 30 minute exposure to 140˚F will kill most pathogens. Maintaining
the compost pile at 145˚F for at least two weeks is
necessary to kill most parasite eggs. However, excess
heat (>150˚F) will kill beneficial microbes, and increase
the risk of combustion. Low temperatures indicate a
lack of food, oxygen or moisture. Mixing or turning the
compost pile will redistribute food, moisture, and oxygen and is important for consistent composting of the
entire pile.
Completion
Once the “active” stage of composting is finished,
the temperature will decline even with the addition
of moisture or oxygen. At this point, the pile will be
approximately half of the original volume. As the compost pile cools, this is called “curing.” Curing allows
microbes that thrive at lower temperatures to breakdown some of the remaining compounds in the pile.
Curing is complete when the pile temperature is similar
to the surrounding temperature. The entire process
start to finish generally takes 6 months of well managed composting. This timeline may vary depending
on the size of the pile and the amount of bedding.
Managing Compost to Benefit the Environment
Gas and odor production can be minimized with a well
managed compost pile. Too much nitrogen (manure)
relative to carbon (bedding) can produce higher ammonia and odor. If possible, locate the pile downwind
from sensitive areas and neighbors.
The following measures will help reduce the environmental impact of a compost system (NRAES, 1992):
1. Good overall management, including pile composition, temperature, and moisture control will keep the
process efficient and reduce the loss of nitrogen.
2. Maintain moisture content below 60% to reduce
leaching of nutrients.
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3. Prevent the runoff from the compost pile, stored
raw materials, and finished compost product from
entering surface water. The runoff can be directed
into a holding pond, or over a vegetated infiltration
area.
4. Divert clean runoff water from uphill sources
around the compost area.
5. Maintain appropriate separation distances (Table 2).
Once the compost is cured, it should be land-applied
with the same care and attention as manure that is discussed in the next section.
application suggestions below to use those nutrients where they are most needed.
When nutrients are applied in excess, or applied immediately before a heavy rain for example, the crop or
vegetation cannot consume the nutrients in a timely
matter. The nutrients and manure components are
then susceptible to surface water runoff and leaching.
When selecting areas and methods for land application, the separation distances discussed in Table 2 are
important. Also keep the following guidelines in mind:
•
Avoid application to frozen ground. Where absolutely necessary, apply to land with the most cover,
and furthest from water sources
•
Avoid spreading on steep slopes
•
Maintain a 100-ft distance from wells, springs,
streams, lakes and ponds
•
Spread as evenly as possible.
•
Incorporate the manure into the soil
Land Application
Manure has value when it can be spread on fields as a
form of fertilizer. Like any fertilizer, manure application
should be managed to provide the plant with required
nutrients, avoiding over-application. This makes not
only environmental sense, but also economic sense!
However, there are some human and horse health risks
that horse owners should be aware of.
* Fresh horse manure should never be applied to
gardens because of the risk of E. Coli. The close
contact between adults and children with the soil
and plants in a garden increases the risk of transfer
of this pathogen.
* If there is bedding mixed with the manure, a “nitrogen enhancement method” is recommended
before land application to avoid stunting plant
growth. The reader is referred to “A Horse Owner’s
Guide” by James (2005) for more specific details.
Balancing the crop needs with the manure nutrients
is called nutrient management planning. This is like
figuring out how much of a wall you can cover with the
paint you purchased. Use too little manure and your
crop growth will suffer (wall will show through the
paint). Use too much manure and it may move where
it should not (use too much paint and it could drip all
over!). When you develop a nutrient management
plan, you have a certain amount of P2 O5 in the manure
(paint left in the can), and a recommended application
rate to grow the type of crop you want (coverage
rate specified on the back of the paint can). Dividing
the P2 O5 in manure (amount of paint in can) by the
recommended application rate (coverage rate) gives
you the number of acres (amount of wall) you can
cover without exceeding the crop nutrient needs.
*Composting kills the parasite eggs and larvae in
manure so the human and horse health risks are
reduced. However, compost is still an amendment
to the soil that contains nutrients. Follow the land
The three things you need for a nutrient management
plan are manure analysis results, soil test results, crop
type and yield goal for the land where you are applying. Initially, you can use book values for manure
* Spreading fresh manure on active pastures increases the risk of parasite transfer from the manure to the horse. During a hot, dry period, it could
take two to four weeks for the sun to kill the larvae
in evenly spread manure on an inactive pasture.
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characteristics, but having a representative manure sample tested will provide more specific values for your farm.
Composted manure will have a considerably different makeup than the fresh manure example provided below. A
soil test will do two things: (1) tell you the current nutrient value in the soil already; and (2) provide crop nutrient
needs as part of the report. With the manure characteristics and soil test results, you can then plan your nutrient
application.
In “A Horse Owner’s Guide to Good Stewardship”, James (2005) describes the steps taken in a nutrient management plan using the following example:
Step 1: The soil test report says each acre of your mostly grass pasture needs:
Pound/Acr e
N
P 2O 5
K 2O
60
35
80
Step 2: You have one 1,000-lb horse. Based on book values, the manure will contain the following nutrients.
Its manure will have:
Pound/Year
N ( P l a nt -Availab le )
P 2O 5
K 2O
32
40
72
Alternatively, you could calculate these numbers based
on the amount of manure, and a manure sample analysis. Assume that the amount of N available for crop use
is only 1/3 of the amount in the test results.
Step 3: Look at the N and P2O5 numbers from the soil
test. In the example numbers from Steps 1 and 2:
•
The manure from the horse will have about ½ of
the N needed for 1 acre of pasture
However, the manure will have slightly more pounds of
P 2O5 than 1 acre of pasture needs
•
Therefore, you will need at least 1 acre of of pasture to spread the manure and use up the phosphorus
•
You can use the same process for any number of
horses or any other crops
•
You can add further nitrogen to meet your crop
needs, but remember that the manure already
provided about half the crop needs. Your other N
source, such as inorganic or commercial fertilizer
only needs to provide half of the N needs.
Summary
Managing manure is a requirement of horse owners.
However, this waste stream can be source of additional crop and plant nutrients when handled correctly.
There are several best management techniques that
reduce or eliminate the movement of nutrients, organic
matter and pathogens into water sources and air, but
carefully consider the time, energy and cost of each
technique. By understanding the nutrient value of the
manure and the crop needs, the fertilizer value of manure can be fully recognized and used. Composting is
an additional way to treat the manure, allowing manure
to be used for other purposes.
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References
NRAES. 1992. On Farm Composting Handbook. Northeast Regional Agricultural Engineering Service, Ithaca, NY.
James, R. 2005. A horse owner’s guide to good stewardship. LPES Small Farms Fact Sheets. Midwest Plan Service: Ames, IA.
Koelsch, R. 2001. Lesson 1: Principles of Environmental Stewardship. In Livestock and Poultry Environmental
Stewardship Curriculum. Midwest Plan Service: Ames, IA.
Russell, J. 2009. Grazing management to limit non-point source pollution in pastures. Grazing Management for
Water Quality Protection. eXtension. < http://www.extension.org/pages/23756/grazing-management-for-waterquality-protection> Accessed 2-Sept-11.
SDSU CES. 1998. Farm-A-Syst: Farmestead Assessment System. Extension Special Series 33: Water Quality.
Brookings, SD.
Buchanan, M. and associates. HORSE MANURE MANAGEMENT: A Guide for Bay Area Horse Keepers. Council
of Bay Area Resource Conservation Districts. < http://www.acrcd.org/Portals/0/Equine%20Fact%20Sheets/ManureMgtBooklet.pdf > Accessed on 10-Jan-12.
Contact Information
For more information on horses, contact SDSU Equine Specialist Dr. Rebecca Bott at 605-688-5412 or by
email, [email protected].
For further information on waste management systems, contact SDSU Air Quality and Waste Management
Specialist Dr. Erin Cortus at 605-688-5144, or by email [email protected].
South Dakota State University, South Dakota counties, and USDA cooperating. South Dakota State University adheres to AA/EEO
guidelines in offering educational programs and services.
Publication: 02-2018-2012
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