Dan Miller, Mindy Spiehs, and Bryan Woodbury USDA-ARS, Lincoln & Clay Center, NE Reduced sulfur emissions and feeding distillers byproducts
Nov 10, 2014
Dan Miller, Mindy Spiehs, andBryan Woodbury
USDA-ARS, Lincoln & Clay Center, NE
Reduced sulfur emissions and feeding distillers byproducts
Why Study Reduced Sulfur in Cattle Feedlots?
• Reduced sulfur gases very smelly• H2S (rotten eggs)• Methyl sulfides (even worse!)
• H2S reporting issue (not in feedlots)• ATSDR 30 & 70 ppb• H2S levels very low
Koelsch et al, 2004
How is TRS related to distillers byproducts?
• Wet distillers grains with solubles (WDGS)• Depleted in starch• Enriched in CP, oil, P and S• Sulfate due to sulfuric acid use• Fed at high levels (up to 50%)
Sulfate,Amino Acids
H2S,
Methyl SulfidesRumen Bacteria
Research Questions
Q: How does diet
effect sulfur emissions?
Q: Where are cattle
feedlot pen ‘hot spots’?
Q: Sulfur sources:
manure or soil?
WDGS Study #1
• 160 steer calves, 10 per pen• Concrete floor• Four levels WDGS (0, 20, 40, 60% on
DM basis)• Pens cleaned 3-4 weeks• Collect manure composite for each pen
at monthly intervals• Measure H2S content of manure• Determine relative TRS emission
Feeding >20% WDGS increases H2S content in the manure.
Manure Composition
WDGS in diet (% DM basis)
Constituent 0% 20% 40% 60% SEM
Total S (mg/g DM) 5.1a 8.7b 11.7c 14.2d 0.3
H2S-S (mg/g DM)
1.57a 3.07a 8.85b 16.41c 0.88
Varel et al., JEQ 2008
Measuring Relative TRS Emission
• Fresh manure sample (consistent surface area)
• Air flow 1 L/min (internal fan to mix)• Sample airstream for total reduced S (TRS)
Three highest values averaged & background subtracted
TRS Emission ProfilePen 3 (40% WDGS) 8/20/07
0
0.2
0.4
0.6
0.8
1
1.2
0 2 4 6 8 10 12
Gas sample
H2S
, pp
m
Manure Added
Manure Removed
• Feeding >20% wet distillers increases H2S emission.
• Similar result for large-scale feedlot?
WDGS Study #1WDGS Study #1
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0 20 40 60
Percentage Wet Distillers Grains
To
tal
Red
uce
d S
ulf
ur,
pp
m8/20/2007
9/24/2007
10/22/2007
a aa a
b
b
b
c
a a
b
c
WDGS Study #2a(During Production)
• Eight pens• Working feedlot (concrete & soil)• Two levels WDGS (0 & 40% on DM
basis)• Collect manure composite (feed
bunk area) for each pen at roughly monthly intervals
• Determine relative H2S emission
Study #2 Relative TRS Emission
• 0.7 to 2.5-fold increase for WDGS • Low moisture content on 5/5 and 6/16
2008 Feedlot Study
0.00
0.10
0.20
0.30
0.40
0.50
0.60
4/14 5/5 6/2 6/16
Date
H2S
, pp
m0%
40%
P = 0.001
P = 0.079
P = 0.002
P = 0.088
WDGS Study #2b(Post Production—Lingering
Effects?)
• Four pens (2 WDGS, 2 DRC)• Utilize EC to select 20 sites per pen
Represent entire surfaceClassified sites as ‘Mound’ or ‘Edge’
• Measure H2S flux with chambers• Collected soil samples for analysis
Moisture contentOrganic matter content
Comparing Field Emissions
Analysis of Results—Pen Average
Source Pr > F
Diet 0.037
Site 0.008
Diet*Site 0.407
Mound
Edge
DRC 8a 14.5b
WDGS 11.5a 21.0c
WDGS Study #3Multi-year, pen emission
• Ten pens (5 per diet treatment)• Twelve sites per pen (mound vs.
edge)• Two levels WDGS (0 & 40% on DM
basis)• Determine relative TRS emission
from the soil over two production cycles
WDGS Study #3Relative TRS emission
• WDGS flux 0.3 to 4-fold higher on 5 of 7 dates.
WDGS Study #3Edge versus Mound
• Larger relative emission in control diet.
• WDGS consistent but not significant
Diet Mound EdgeWDGS 3.35 5.56Control 2.21A 2.99B
T-test 0.001 0.028
Research Questions
Q: Diet? Q: Location?Q: Source?
A: 40% WDGS
increases TRS.
A: Pen edges more important
than mound
A: Manure strongest source.
Future Directions• What mechanism for soil emission?
• Degasing or sulfate reduction in the soil?
• Does this matter at the fence line?• What about low S WDGS?
Questions?