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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



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


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

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


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 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


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


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






Low volume (not turned on day 24)

High volume (not turned on day 24)


0 10 20 30 40 50









Low volume

Days after windrow formation

High volume

Temperatuire (


Time (days)



Temperatuire (


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


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-


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


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


3 Concentration (ppm)









~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


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 -


2. Brown Bear Corporation, Corning Iowa:

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 >

Project Reports > Search the database

for project # SW00 -040


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