A g r i c u l t u r a l I n n o v a t i o n s
In -H o u s e C o m p o s t i n g i n H i g h -R i s e , C a g e d L a y e r F a c i l i t i e s
Richard T. Koenig
Washington State University, Pullman
Introduction
M
anure handling, storage, and disposal are common
problems facing poultry producers in the United
States. Fly and odor control, urban encroachment, a limited
nearby land base for manure disposal, and increased regula-
tory pressures necessitate the development of alternatives
to traditional scrape and haul systems.
One alternative for high -rise layer facilities is to compost
manure inside of the buildings housing laying hens. Re-
search showed that the addition of a carbon source coupled
with frequent aeration of compost in a layer house pro-
duced temperatures high enough to inhibit fly reproduction
in the material.
In -house composting offers promising solutions to common
problems faced by egg producers. Since manure can be
treated within the layer facility, odors associated with ma-
nure disturbance and handling when cleaning out a build-
ing are reduced. Fly control is achieved with heat, thereby
reducing the need for pesticides. In addition, a more uni-
form and marketable compost product is produced, which
greatly reduces the need for a nearby agricultural land base
for manure disposal. Research conducted by others [1] also
has shown that the final weight and volume of material
produced are at least 35% lower after in -house composting
compared to traditional systems where poultry manure ac-
cumulates undisturbed.
This article summarizes the in -house composting process
and relevant research findings from a Western SARE pro
(Introduction continued on page 2)
Inside this fact sheet:
# Introduction
# High -Rise, Caged Layer Facilities
# An Overview of In -House Composting
# Managing Compost Inside Poultry Facilities
# Economic Evaluation
# SARE Research Synopsis
# References
SARE Agricultural Innovations are based on
knowledge gained from SARE -funded projects.
Written for farmers and agricultural educators,
these peer reviewed fact sheets provide practical,
hands -on information to integrate well -researched
sustainable strategies into farming and ranching
systems. The articles are written by project
coordinators and published by SARE.
Continental U.S. and areas with similar climate and high
-rise, caged layer poultry production systems. This SARE
research was conducted in the western U.S., but similar
research has been done in Pennsylvania, Maryland and
Georgia.
G E O G R A P H I C R A N G E :
F a c t S h e e t Practical applications for
s u s t a i n a b l e a g r i c u l t u r e
PDF available at www.sare.org/publications/factsheet/pdf/04AGI2005.pdf
Sustainable Agriculture Research & Education
F. Dean Miner, Jr.
Utah State University Extension, Provo
Bruce E. Miller
Utah State University, Logan
Matt D. Palmer
Utah State University Extension, Tooele
County Extension Agent Dean Miner sifts through
composted poultry manure. Photo by Gary Neuenswander
In-House Composting in High -Rise, Caged Layer Facilities SARE 2
ject in Utah for producers interested in
adopting the process on their farms. Ad-
ditional information on in -house com-
posting can be found on the Internet and
in the publications cited in this article.
High -Rise, Caged Layer
Facilities
The standard structure design for high -
rise, caged layer facilities involves hous-
ing poultry in offset -stacked cages in the
upper floor of the structure. Manure
from the cages is directed with plastic
sheeting into the storage area below
(Figure 1). Manure may accumulate for
several months or more before buildings
are cleaned out.
Automated fans housed in the lower portion of the struc-
ture control ambient temperatures in the cage area by
drawing air in through evaporative cooling screens located
in the roof and expelling it through the walls in the manure
storage area. The fans also serve to vent ammonia and
other gasses from the building, and to accelerate manure
drying. Fly control is normally achieved by supplying a
feed -based larvicide to laying hens coupled with topical
applications of insecticides on the manure as needed to
control outbreaks. Odor and fly complaints are commonly
associated with the clean -out process when accumulated
manure is disturbed for loading and transport.
An Overview of In -House
Composting
Composting is possible inside high -rise facilities using
equipment sized to fit in the manure accumulation area
of the structure. Cooperators at the sites where this
SARE research was conducted used a Brown Bear
model 24C compost turner [2] fitted to a skid -steer drive
unit to aerate the materials (photo A). The skid -steer is
the same power unit that, when fitted with a loader
bucket, is used to remove material from the buildings.
To prepare for a compost cycle, a carbon source such as
straw or sawdust is spread on the floor after cleaning out
a building. Manure is allowed to accumulate on the car-
bon bed for 2 to 4 days before forming the material into
windrows with the turner. The material is turned
(aerated) every two to four days, depending on the size
of windrows and material temperature.
Aerating promotes rapid decomposition by microorgan-
isms. The metabolic heat produced by the microorganisms
is capable of generating temperatures in the compost above
the lethal limit for fly larvae (110 oF). Aerating also rotates
fresh manure into the center of the pile where high tem-
peratures kill new fly larvae. Material is removed when the
volume exceeds the operational capacity of the turner.
In -house composting differs from traditional composting.
Since manure is being added continuously, the product at
the end of a cycle is not finished compost. However, as a
result of frequent mixing and partial decomposition, the
material is more uniform and has a lower moisture content
and less odor than fresh poultry manure. If desired, fin-
Figure 1. Schematic of a high -rise layer structure. Fans in the wall of the struc-
ture draw air out under negative pressure (suction). This pathway of air flow
serves to vent ammonia and other gasses out of the structure, minimizing expo-
sure of poultry.
Photo A. A Brown Bear 24C compost turner [2] fitted to a
skid -steer drive unit turns compost inside a high -rise layer
structure.
In-House Composting in High -Rise, Caged Layer Facilities SARE 3
ishing can occur outdoors in a conventional composting
system, or partially composted material can be land -
applied without finishing. Practitioners should check
with state and local officials regarding regulations on com-
posting facilities and compost quality standards before
marketing the products of this process as compost.
An essential component of in -house composting is the
negative pressure ventilation system that vents ammonia
and other gasses from the composting area. This reduces
the exposure of poultry and employees to potentially toxic
gasses produced during composting. High concentrations
of harmful gasses may still be present in the composting
area, so employees working there should be equipped with
appropriate monitoring and respira-
tory safety devices. Also, practitioners
should be aware of impending air
quality rules designed to regulate am-
monia emissions from poultry farms.
Careful attention to composting con-
ditions, particularly the carbon to ni-
trogen (C:N) ratio of the material, can
limit ammonia emissions. There is
also some evidence (cited later) that
chemical amendments can be used to
reduce ammonia volatilized from com-
posting manure.
Managing Compost
Inside Poultry
Facilities
Details on composting processes and
methods are outside the scope of this
article but are presented elsewhere in
comprehensive manuals [3]. Two of
the most important factors for success-
ful in -house composting are the appro-
priate C:N ratio and moisture content
of the material. Carbon to nitrogen
ratio should be in the range of 20:1 to
40:1, with moisture contents in the
range of 40 to 65% by weight. Practitioners are encouraged
to purchase a comprehensive reference on composting
methods, and to periodically have samples of material ana-
lyzed to compare results to desired ranges and make ad-
justments as necessary.
Carbon requirements
Initial research showed that high composting temperatures
could be achieved in -house using relatively low rates of
carbon material (200 to 600 lbs per 1,000 square feet of
floor area, [4, 5]) (Figure 2). The resulting C:N ratio of the
compost, however, was approximately 10:1, much lower
than recommended for optimum composting. Compost-
ing with a low C:N ratio contributes to high rates of am-
monia gas evolution and atmospheric ammonia concentra-
tions inside the layer facility. While using less carbon ex-
tends the length of time compost can accumulate before
the volume exceeds the capacity of the turner, the resulting
high rates of ammonia volatilization are not sustainable
from an air quality perspective.
Increasing the amount of carbon used to produce a target
C:N ratio of 20:1 to 40:1 will reduce ammonia volatiliza-
tion. Formulae are available to calculate the exact amount
of carbon necessary to achieve a target C:N ratio, knowing
the characteristics of the manure and carbon source mate-
rial [3]. Higher C:N ratio carbon sources are desirable, as
they reduce the total amount of carbon required. Depend-
ing on the source, from 1/3 to 2 pounds of carbon per
pound of manure would be required for an optimum C:N
ratio with in -house composting.
Figure 2. Daily compost temperatures measured during a seven -week in -house cy-
cle. The treatments consisted of high and low initial volumes of composting material.
Arrows indicate when compost was turned. The horizontal line represents the lethal
limit for fly larvae (43 oC = approximately 110 o F). The * indicates when certain rep-
lications of the treatments were not turned on day 24. Data from Miner et al. (2001)
[5]. 22 24 26 28
30
40
50
60
70
Low volume (not turned on day 24)
High volume (not turned on day 24)
*
0 10 20 30 40 50
0
10
20
30
40
50
60
70
Low volume
Days after windrow formation
High volume
Temperatuire (
oC)
Time (days)
*
[
Temperatuire (
oC)
In-House Composting in High -Rise, Caged Layer Facilities SARE 4
According to published research, a single laying hen pro-
duces approximately 0.058 lb manure per day (41% mois-
ture equivalent) [6]. The C:N ratio of layer manure aver-
ages 8.5 [4, 5]. Using this information, together with data
on the carbon source and the formulae cited above, the
total amount of carbon needed for a given number of birds
and length of time composting will occur can be calcu-
lated. Research [1] also suggests that as much as 35% of the
manure decomposes during in -house composting, so some
adjustment in the amount of manure may be warranted
when forecasting carbon requirements.
Since manure is added continuously over time, all of the
carbon should not be added at the beginning of an in -
house composting cycle. Divide the carbon into three or
more separate applications made at regular intervals during
a cycle. For example, in a six -week cycle, add approxi-
mately 33% of the carbon at the beginning of the cycle,
33% after two weeks, and the final 33% after four weeks.
Turning frequency
Research demonstrated the importance of turning fre-
quency on maintaining compost temperatures above the
lethal limit for fly larvae. Results showed that critical tem-
peratures could be achieved by turning the material once
every 2 to 3 days (Figure 2). Missed turning events re-
sulted in a rapid drop in temperatures below the critical
value (see insert graph in Figure 2). Regular monitoring of
compost temperatures is critical to determine when to aer-
ate the materials. An inexpensive compost thermometer
should be purchased to monitor windrow temperatures.
Temperature monitoring also can be used as a trouble-
shooting tool. If temperatures do not reach critical values
for fly control after a turning event, check compost mois-
ture content and C:N ratio and compare to desired ranges
cited above or in handbook references [3].
Average compost temperatures increased over time as the
total volume and insulating capacity of the material in-
creased (Figure 2). However, frequent turning is still nec-
essary to ensure that fresh material deposited on top of the
windrows is rotated into the pile and heated to kill fly lar-
vae. Flies develop from egg to adult stages in as little as
nine days under ideal conditions. Therefore, ensuring that
all manure is rotated into compost piles at least once every
nine days is critical for successful fly control.
Composting manure from young poultry
(pullets)
Composting manure from pullets was less successful in
research. Compost failed to reach critical temperatures for
fly control despite more frequent turning and supplemen-
tal carbon additions. The failure of composting with pullet
manure was attributed to a higher moisture content com-
pared to layer manure. Additional research on pullet ma-
nure composting is warranted. Increasing the rate of car-
bon may further promote successful pullet manure com-
posting.
Moisture content
In the arid climate where this research was conducted, the
moisture content of in -house compost declined to as low as
30% by weight during summer months [4, 5], well below
the acceptable range of 40 to 65% [3]. Critical temperatures
for fly control were still achieved with this low moisture
content. Although studies in
which water was added to
composting materials were
not conducted, supplemental
water may increase compost-
ing temperatures in situations
where the moisture content of
material declines below criti-
cal levels.
Compost moisture content
was higher in winter than in
summer due to higher relative
humidity, lower ambient
temperatures and reduced
operation of ventilation/
cooling fans in the buildings
during winter. More fre-
quent turning and the addi-
Utah egg producer Mike
Shepherd holds composted
poultry manure. Photo by
Gary Neuenswander
Research demonstrated the importance of turning fre-
quency to maintain high compost temperatures.
In-House Composting in High -Rise, Caged Layer Facilities SARE 5
tion of higher rates of carbon during winter are recom-
mended to accelerate drying and promote higher material
temperatures.
Fly control
The farmer cooperators on this SARE research project
were able to discontinue using a feed -based larvicide and
shift to topical applications of an insecticide when needed
as long as the material was managed appropriately to main-
tain high temperatures. Fly outbreaks, though infrequent,
did occur when equipment broke down and turning sched-
ules could not be maintained.
Similar success in controlling
flies with in -house composting
has been reported by other re-
searchers [7].
Ammonia volatilization
and control
One of the main challenges with
in-house composting is the accu-
mulation of high levels of ammo-
nia and other gasses inside layer
houses and venting of these gas-
ses from the facility. Active bio-
logical decomposition coupled
with the low carbon to nitrogen
ratio and frequent turning of the
material contributes to higher
ammonia levels than in high -rise
layer facilities where manure ac-
cumulates in static beds. Moni-
toring showed that atmospheric
ammonia in the composting area
peaked well above safe levels for
humans and poultry when the
compost was being turned (Figure
3). Atmospheric ammonia was also
higher in winter when fan use to
cool buildings was reduced. Am-
monia concentrations in the cage area were less than 50%
of the concentrations in the composting area due to air
flow patterns created by operation of the ventilation sys-
tem [8].
There are several options to manage atmospheric ammonia
during in -house composting. Practices that conserve nitro-
gen and reduce ammonia volatilization are the most desir-
able and environmentally sustainable solutions. Using
rates of carbon calculated to maintain optimum C:N ratios
will increase ammonia assimilation by microorganisms and
reduce ammonia volatilization. Chemical amendments
such as aluminum sulfate also have the potential to reduce
ammonia volatilization from in -house compost [9], but
more research remains to be done in this area. To reduce
exposure in the short term, facility personnel where this
research was conducted would over -ride the automated fan
system for 15 to 30 minutes to vent ammonia when com-
post was being turned. It is recommended that facilities
using in -house composting invest in ammonia gas sensors
to prevent exposure of workers and poultry to high levels
of atmospheric ammonia. In light of impending air quality
regulations, practitioners of in -house composting also are
cautioned to adopt practices that reduce ammonia emis-
sions from poultry facilities.
Economic Evaluation
Cooperators on this project reported cost savings associ-
ated with reduced pesticide use for fly control, removal of
less material from the buildings at cleanout, and the pro-
Figure 3. Ammonia concentrations over time in the manure storage area of a high -
rise layer structure during in -house composting. The peak concentration occurred
during a compost turning event. The –— line indicates the 8 hour human health ex-
posure limit. The — — line indicates the 10 minute human health exposure limit.
Data are from Koenig et al. (in press) [9]. Time (minutes after 13:30)
0 500 1000 1500 2000 2500 3000 3500 4000 4500
NH
3 Concentration (ppm)
0
10
20
30
40
50
60
}
~90 minutes
In-House Composting in High -Rise, Caged Layer Facilities SARE 6
duction of a higher value and saleable product. Additional
costs were incurred for turning the compost. Based on par-
tial budget analysis including these costs, annual savings
equaled $6,000 per building per year. Total annual savings
at a 330,000 laying hen facility was approximately $30,000.
This was equivalent to a 65% reduction in costs associated
with pesticides and manure removal and disposal. Overall,
the greatest cost reduction was realized from reducing the
amount of pesticide used. The savings offset the costs of
new compost turners and other equipment required for in -
house composting in less than three years. Additional op-
portunities were created to use waste cardboard and egg
shells from a cracking operation as a car-
bon source and amendment, respec-
tively, to the compost.
SARE Research Synopsis
The goal of SARE research project In -
house composting in high -rise, caged
layer facilities was to develop opera-
tional parameters for in -house compost-
ing. Specific objectives were to: 1)
evaluate carbon source, rate, and turn-
ing frequency variables for their effects
on compost temperatures; 2) evaluate
amendments and process controls to
reduce ammonia volatilization from
composting manure; and 3) conduct a
partial budget economic analysis of in -
house composting relative to traditional
methods of handling and disposing of
poultry manure.
The research was initiated in 1998 at a
330,000 -layer egg farm and later ex-
panded to a second facility of similar size. Both farms were
located in central Utah and featured high -rise, caged layer
buildings. Each building housed approximately 65,000 lay-
ing hens. The manure accumulation area in each building
was divided into multiple quadrants and treatments ap-
plied to separate quadrants in a randomized complete
block experiment design. Each treatment was replicated
three times within a building.
Two trials were conducted to evaluate the effect of carbon
rate and turning frequency on compost temperatures. Tri-
als indicated that initial carbon rates of 200 to 600 lbs per
1,000 square feet of floor area were adequate to achieve
critical temperatures for fly control as long as material was
turned at least once every three days during early stages of
composting. Wheat straw and sawdust were equally effec-
tive as carbon sources.
Trials demonstrated the importance of turning frequency
to maintain high compost temperatures. Temperatures
peaked on the day of turning and declined rapidly thereaf-
ter. A turning frequency of once every two to three days
was essential to maintain high in -house compost tempera-
tures in layer manure. We also found that rotating fresh
manure with live larvae from the surface to the interior of
the pile enabled heat to kill the larvae. Longer intervals
between turning events could be used later in the compost-
ing cycle when higher volumes of compost
were present.
In -house composting with manure from
young birds (pullets) was generally unsuc-
cessful due to the higher moisture content of
pullet compared to layer manure. Two addi-
tional trials were completed evaluating the
effects of turning frequency (three or six
days per week) and carbon rate (400 or 800
lbs/1,000 square feet of floor area) on com-
posting pullet manure. Results indicated that
increasing the turning frequency could accel-
erate pullet manure drying and increase
compost temperatures. Doubling the rate of
carbon was less effective than increasing
turning frequency.
In all of these studies, the C:N ratio of com-
posting material was in the range of 10 to 12:1
throughout a cycle. Composting with low
C:N ratios generated high levels of atmos-
pheric ammonia within the poultry facilities.
While no reductions in egg production or increases in bird
mortality were noted, high ammonia levels were a health
concern for workers and poultry.
Initial efforts to control atmospheric ammonia were fo-
cused on documenting the spatial and temporal variability
of ammonia inside high -rise facilities during composting.
Atmospheric ammonia levels were shown to vary spatially
within the buildings, with higher concentrations found
near the center of the building away from ventilation fans.
Concentrations frequently exceed 25 ppm ammonia (the
upper limit for eight -hour exposure of workers) in the ma-
nure storage area. Atmospheric ammonia concentrations
were approximately 50% lower in the cage area. Spikes in
atmospheric ammonia exceeding 35 ppm (the upper limit
for 10 -minute exposure) occurred immediately after a
Researchers found annual
savings of $6,000 per hen
house per year.
Ohio State University
Photo Library
In-House Composting in High -Rise, Caged Layer Facilities SARE 7
References
1. Thompson, S.A., P.M. Ndegwa, W.C. Merka and A.B. Webster. 2001. Reduction in layer manure weight and volume
using an in -house layer manure composting system under field conditions. Journal of Applied Poultry Research 10:255 -
261.
2. Brown Bear Corporation, Corning Iowa: http://www.brownbearcorp.com/
3. Rynk, R. (Ed). 1992. On -Farm Composting Handbook. Publication #54 of the Northeast Regional Agricul-
tural Engineering Service (NRAES).
4. Miner, F.D., R.T. Koenig and B.E. Miller. 2000. In -house composting in high -rise layer facilities. Journal of Applied
Poultry Research 9:162 -171.
5. Miner, F.D., R.T. Koenig and B.E. Miller. 2001. The influence of bulking material type and volume on in -house com-
posting in high -rise, caged layer facilities. Compost Science and Utilization 9:50 -59.
6. Lorimor, J.S. and H. Xin. 1999. Manure production and nutrient concentrations from high -rise layer houses. Applied
Engineering in Agriculture 15:337 -340.
7. Pitts, C.W., P.C. Tobin, B. Weidenboerner, P.H. Patterson and E.S> Lorenz. 1998. In -house composting to
reduce larval house fly, Musca Domestica L., populations. Journal of Applied Poultry Research 7:180 -188.
8. Koenig, R.T., F.D. Miner, Jr., B.E. Miller and J.D. Harrison. Spatial and temporal variability of atmospheric ammonia
during in -house composting in high -rise, caged layer facilities. Compost Science and Utilization (in press).
9. Koenig, R.T., M.D. Palmer, F.D. Miner, Jr., B.E. Miller and J.D. Harrison. 2005. Chemical amendments and process
controls to reduce ammonia volatilization during in -house composting in high -rise, caged layer facilities. Compost Sci-
ence and Utilization 13:141 -149.
SARE Fact Sheet #04AGI2005
compost turning event and lasted for less than 60 minutes.
Ammonia levels also increased over time as compost vol-
umes increased. In a series of laboratory and limited in -
house trials, process controls and chemical amendments
such as aluminum sulfate showed potential to reduce am-
monia volatilization from composting poultry manure.
This fact sheet is based on a SARE -funded project.
For more information, please visit www.sare.org >
Project Reports > Search the database
for project # SW00 -040
