This study evaluated the potential for stocking density manipulation to reduce feedyard dust levels. Researchers blocked pens into control (normal 150 ft2/hd density) and treatment (double density of 75 ft2/hd) groups. Dust sampling found PM10 concentrations, emission fluxes, and emission factors were significantly lower in doubled density pens compared to controls, indicating increased stocking density can effectively reduce dust through manure compaction and moisture retention.

1. Evaluating the Dust Abatement Potential
of Stocking Density Manipulation at
Open-Lot Cattle Feedyards
K. Jack Bush, Research Associate, Texas A&M AgriLife
Research; Brent W. Auvermann, Professor of Agricultural
Engineering, Texas A&M AgriLife Research; Gary W. Marek,
Postdoctoral Research Associate, Texas A&M AgriLife
Research; Kevin Heflin, Extension Associate, Texas A&M
AgriLife Research; Sharon Preece, Senior Research
Associate, Texas A&M AgriLife Research.

2.  Feedyard Dust
◉ Annoyance
◉ Health Hazard
◉ Traffic Hazard
Introduction

3.  Manure Harvest
 Water application
◉ Sprinkler, Water Truck etc.
 Chemical Amendments
◉ Oils and Resins
 Feed Management
◉ Feed Timing
◉ Increased Lipids
 Stocking Density
◉ Low Cost Alternative?
Dust Abatement Measures

4.  Feedyard Pens Blocked
◉ Control Pens = Normal Stocking Density of 150 ft2/hd
◉ Treatment 1 = Double Stocking Density of 75 ft2/hd by 50%
Reduction in Pen Area
◉ Treatment 2 = Double Stocking Density of 75 ft2/hd by 100%
increase in # of Cattle
Methods

5. Stocking Density Treatments

6.  Mobile sampling platforms provide path averaged airborne
dust concentrations
 2 Samplers used
◉ Optical Particle Sizer (OPS) (model 3330, TSI inc., Shoreview,
MN)
◉ Aerosol Monitor (model DUSTRAK II 8530, TSI inc., Shoreview,
MN)
 Sampler Inlet set at 22 inches above ground
 Collocated with GPS Device
 Cruise Control Fabricated to limit speed to 1mph
PM10 Sampling

7.  ATV Outfitted with
OPS and GPS
Devices
Sampling Platforms

8.  UTV Outfitted with
DUSTRAK II and
GPS
Sampling Platforms

9.  OPS Driven in Loop
Downwind of J pens
 Dustrak Driven in Loop
Downwind of K pens
 Each loop takes 30
Minutes
 15 Minutes on Downwind
 15 Minutes on Upwind
Sampler Path

10.  Southerly Winds
 Dry Conditions
 Sample in the evening to take advantage of the “Evening
Dust Peak” when dust concentrations are highest
PM10 Sampling Criteria

11.  Weather Station recorded surface data for entire
sampling period
Weather

12.  AERMOD (Lakes Environmental, Waterloo, ON)
◉ EPA Regulatory model
◉ Used to Calculate PM10 Emission Rates ( g/m2 –sec) and
Emission Factors (kg/1000 hd-day) using a standard scaling
approach
Dispersion Modeling

13. Corral Surface Condition Description
A
Little to no uncompacted manure visible on the corral surface;
hard and smooth, may be moist to dry
B
Well compacted surface easily visible; small clods of uncompacted
manure present
C
Compacted surface sparsely visible, nearly covered with small
manure clods
D
Compacted layer not visible, completely covered with dry,
uncompacted manure in chunks and/or clods
E
Completely covered with <1” of finely textured, dry, uncompacted
manure “fluff”
F
Completely covered with >1” of finely textured, dry, uncompacted
manure “fluff”
W Wet; sloppy and/or uneven surface >25% of corral area
Pen Surface Assessment

14.  B
Pen Surface Assessment

15.  C
Pen Surface Assessment

16.  E
Pen Surface Assessment

17. Results

18. Results
0
100
200
300
400
500
600
700
J Row K+J Rows
AverageDownwindPM10Concentration(g/m3)
Average Downwind PM10 Concentrations
Control
Treatment 1
Treatment 2

19. Results
0
5
10
15
20
25
30
35
40
45
50
J Row K+J Rows
AverageCalculatedEmissionFlux(g/m2-sec)
Average PM10 Emission Flux
Control
Treatment 1
Treatment 2

20. Results
0
10
20
30
40
50
60
J Row K+J Rows
AverageCalculatedEmissionFactor(Kg/1000hd-day)
Average PM10 Emission Factor
Control
Treatment 1
Treatment 2

21. Post Hoc Tukey Test ( =0.05)
J Row (OPS) K+J Row (DUSTRAK II)
Concentration Emission Flux Concentration Emission Flux
Control - T1 * p = 0.002 X * p=0.001 * p=0.010
Control- T2 X X * p=0.001 *p=0.004
T1-T2 * p = 0.002 X X X
Results
ANOVA ( =0.05)
J Row (OPS) K+J Row (DUSTRAK II)
Concentration Emission Flux Concentration Emission Flux
* p=0.003 X * P= 0.001 * P=0.002

22. Results
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
W
A
B
C
D
E
F
%OfTimesScoreUsed
Surface Condition Score
Corral Surface Assessment Score Frequency
Control Pens
Double Stocked Pens

23.  Boundary
Between
Control and
Treatment
Blocks
Dust Plume

24. Discussion
 PM10 Emissions reduced
◉ Emission Flux
◉ Emission Factor
 Increased Stocking Density Changes Feedyard Surface
◉ Compacting Manure layer
◉ Increasing Moisture Content

25.  JBS Five Rivers
Acknowledgements

26. J Row (OPS Measured) K Row (DUSTRAK II Measured)
Avg 1hr Mass
Concentration
( g/m3)
Avg Emission Flux
( g/m2-sec)
Emission Factor
(kg/1000 hd-day)
Avg 1hr Mass
Concentration
( g/m3)
Avg Emission Flux
( g/m2-sec)
Emission Factor
(kg/1000 hd-day)
Control 632.16 45.15 54.33 339.8 42.16 50.73
Treatment 1 60.56 21.44 12.9 64.99 11.7 7.04
Treatment 2 292.85 21.89 13.18 52 7.56 4.55
Results