Compost Bedded Pack Barns Composting and Design Considerations

Compost Bedded Pack
Barns
----
Composting and Design
Considerations
Joseph Taraba
Department of Biosystems
and Agricultural Engineering
University of Kentucky
joseph.taraba@uky.edu

Compost Barn Research Team
Animal Science Biosystems and
Agricultural
Engineering
Jeff Bewley George Day
Randi Black Flavio Damasceno
Elizabeth Eckelkamp

Challenges That Milk Producers Confront
Cost of production (particularly for small herd)
Feed
Energy
Capital
Bedding
Cow Productivity
Environmental impacts
Water quality
Air quality (odor and GHG)
Animal welfare
Quality of life
Health
Milk quality
Reduced somatic cell counts

Dairy facilities in KY are a
significant source of water
pollution.
-- Ky DOW

The COMPOST BEDDED LOOSE
HOUSING BARN and the solid composted
waste is an important alternative manure
management practice to allow flexibility in
utilization of plant nutrients and organic
matter for soil fertility.
OTHER ENVIRONMENTAL BENEFITS:
- Improved air quality – odor, GHGs (?)
- Reduced fly populations

Non-Confinement-Grazing

Confinement-Freestalls

Confinement- Bedded Pack
Loose Housing Barn

Success for the dairyman is based on
both the management of the bed and
Compost Bedded Pack
the interaction of the bed and the
Loose Housing Dairy Barn
surrounding managed environment
within the structural envelope

General
Compost
Barn Layout

History of the Compost
Bedded Pack
Concept introduced in Virginia in late
1980s by producers
Kentucky’s first barn built in 2002 in
Monroe County
In 2008 there were approximately 30
barns in Kentucky, in Feb 2011 there
were 60
Today we know of 80 barns in Kentucky

Potential Benefits
Improved cow comfort
Lower somatic cell count
Less clinical mastitis
Increased milk
production
Reduced lameness
Improved hoof health
Less hairy heel warts?
Increased cow
longevity
Reduced culling rates
Improved heat
detection
Reduced odor
Reduced fly population
Improved consumer
acceptance?

Potential Liabilities
• Mastitis
• Availability of sawdust
• Considered the best type bedding
• Only for small producers (??)
• Heat production in hot weather that
increases heat stress
• Poor understanding of bed and barn
management leading to significant costs
to operation

This cow is in deep sleep
Is this good or bad?

This is hottest day in 2012
Is this good or bad?

The “Ideal”
Composting Process
NH 3
N 2O

Temperature Dynamics
Adding feces, urine and bedding continuously
changes static bed composting process
Feces Urine Bedding

Stirring
the Bed
2 x per
day
religiously
Rototiller tillage
depth 6-8”
10-12” stirring depth
with deep tillage

Depth of Compost Bed
24 to 48”
10 to 12”
Compost Bedded Pack
Ventilation/Circulation Air
Aerobic Zone
Aerobic/ Anaerobic
Transition Zone
Anaerobic Zone
Ambient
Soil
Temp, o F
120 -140 F

Pack Moisture Control
Biological activity generates heat which
helps to dry the bedding material
Bedding cannot absorb all the water
from urine and manure without
evaporation of water
Unless area per cow more
than doubles in winter
Too wet of a bedded pack reduces
aeration, slows biological activity, slow
heat generation and water evaporation

Heat Losses from
Compost Bedded Pack
Conduction
Radiation
Ventilation/Circulation Air
Evaporation
and Convection

Management of
the Bedded Pack

What we have learned
from assessment of
compost beds

Barn Facility Measurements

Environmental Measurements
• Air temperature, relative humidity, and air
velocity and wind direction (0.05 and 1.2 m);

Bedding Temperature Measurement
Bedding temperature – surface and two different
depths (0.10 and 0.20 m);
Bedding Moisture
Measurement
Bedding moisture – surface to 0.20 m

Stocking Density
Recommended
Stocking Density
ft 2 /cow
Recommended
Adjusted Stocking
Density – ft 2 /cow

Average Water Holding Capacity = 72.7%

Outside
Surface
8 “ deep
4 “ deep

Temporal Compost Bed Monitoring
Bed Moisture
Outside Air T
Bed T 8” deep
Bed Surface T

Fall
Winter

Carbon/Nitrogen Ratio
Bed Carbon/Nitrogen Ratio
50
45
40
35
30
25
20
15
10
5
0
20 30 40 50 60 70 80
Bedding Moisture (% - wb) 0"- 4"

Nutrient Levels in Dairy Manures
Are Highly Variable
(lb/1,000 gal)
Compost bed manure (lb/ton (lb/1,000 - gal) Kentucky) 10 5
3
5 3
10 7
5
(0.6 to 10)
range (5 to 16) (2 to 11) (3 to 21)
(0.6 to 10)
3
3
(0.8 to 5) (0.4 to 8) (0.5 to 21)
(0.8 to 5) (0.4 to 8) (0.5 to 21)
7

Temporal Compost Bed Monitoring

Dairy Barn Compost Bed Densities
Compost Bed
Zone
Tillage Layer – 0-
8”
Below Tillage
Layer
Below Tillage
Layer - High
Traffic Entryway
Dry Matter
Density (#/ft 3 )
Wet Density
(#/ft 3 )
Moisture Content
(%-wb)
11.0 25.7 57%
20.4 62.7 67%
28.0 82.9 66%

Tillage

Rotary Spader

What we have learned
from assessment of
barn structural details

40%
35%
30%
25%
20%
15%
10%
5%
0%
Barn Orientation
Recommended
N (N-S) NE (NE-SW) E (E-W) NW (NW-SE)
| / ̶— \

Roof Pitch
Recommended

Side Wall Eave Height
Recommended

Barn Ventilation/Circulation
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
Box fans High Volume Low
Speed Fans (HVLS)
Natural ventilation Tunnel ventilation

Potential Warm Weather Compost
Bed Drying Rate
- Rototilled bed (~ 55% wb) -
Air Velocity 2" Above Bed Net Water Drying Cow water
Surface
Rate output
mph ft/min #/ft2/day #/day/ft2
4 360 0.9 0.93
2 180 0.6 0.93
0 0 0.2 0.93

Type
Ridge Design
Name
Open Ridge
Open ridge
with cover
Overshot
Hoop
structure
Capped ridge
Recommended

Ridge Opening to Barn Width Ratio
Recommended
Recommended

Airflow Patterns
Overshot ridge - OVR Open ridge with chimney - ORC
The smoke was visually observed when it was
passed through and over the ridge opening

Develop CFD model of compost barn
Wind direction
Wind direction
Open ridge Closed ridge Overshot

Position in the Landscape
HIGH GROUND:
-To reduce the effects of local
obstructions such as trees and
other buildings
-Takes advantage of upslope air
currents
HILLSIDE CUTS:
DEPRESSIONS:
-In upland wind shadow
-Bowl depression subject to
temperature inversions
-Does reduce winter radiation
losses to sky

Feedbunk Space

Waterer Space

Potential Design Flaws
• Not enough space per cow
• Inadequate ventilation
– Sidewalls too low (

Compost Bedded
Pack Success
To generate enough heat --
Need to have a high porosity bed for a level of
oxygen to sustain the compost process. (But not
too high or too low)
- Bed stirring
- Bedding type
- Bedding particle size

Stirring
the Bed
Pulling tillage tool
Wheels following
tillage tool leads to
compaction and
lower temperatures

Moisture
Levels
Just right leads to clean,
comfortable conditions for cow
Too wet leads to poor conditions and
a dirty potentially cold stressed cow
Waterers in bed area can
create a too wet condition

Sawdust
Sawdust/
Shavings
A B
C
Type Bedding
Materials
Shavings

Type Bedding Materials
Not Recommended
Wood chips Hammer milled

1:1 Chopped Straw:sawdust
Chopped Straw
thru 1 “ Screen
Ground Straw
Long Straw

When purchasing bedding –
Buy dry matter, not water
Buy dry matter, not air
The higher the water content of
the dry matter, the less water
that will be able to be absorbed
by the bedding

How Can You Reduce Bedding
Use In Winter
• Allow cow access to pasture in good
weather
• Increase air circulation in barn when
cows are milking or in pasture
– But not to point of losing too much bed
temperature
• Use kiln dry sawdust in winter, green
sawdust during warmer weather
• Stockpile and/or store kiln dry sawdust
under roof or tarp

Why Don’t All Packs Work?
• Stocking density
– too many cows! Poor distribution of cows
• Bed material used
– straw, cedar
• Insufficient bedding volumes
• Inadequate/ineffective stirring
– Stirring frequency (less than 2x/day)
– Depth of stirring (

What are Alternative
Bedding Sources
• Efforts underway to increase sawdust supply
• Green vs kiln dried sawdust
• Ground corn cobs
• Finely chopped soy straw/stubble
• Kenaf?
• Peanut shells?
• Other ideas?
• Need more definitive research and producer
ideas and cooperation to answer these
questions

Questions?

Potential of Contaminated
Water Draining from
Compost Bed

Urine
Drainage
from
Uncompacted
Till Layer
Urine
Drainage
from
Compacted
Till Layer
Drainage
Drainage
DM Density
Compacted Bed
Tilled Layer
Depth
Tilled Layer Depth (in)

Preferential
Flow
Does the Rototilled Layer
Retain Urination Volume?
Diffuse
Flow
11”