Feeding Distillers Grains and Reduced Sulfur Emissions
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For more: http://www.extension.org/67657 Odorous reduced sulfur compounds are produced during manure decomposition and emitted from confined animal feeding operations. Feeding high-sulfur distiller’s byproducts may increase the emission of these compounds. The objectives of a series of feedlot pen studies was to (i) determine if emissions of reduced sulfur compounds from fresh manure and from the feedlot surface where affected if cattle were fed varying levels of distillers byproducts, and (ii) determine the areas within a pen that emit greater amounts of reduced sulfur compounds.
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Feeding Distillers Grains and Reduced Sulfur Emissions
- 1. Dan Miller, Mindy Spiehs, and Bryan Woodbury USDA-ARS, Lincoln & Clay Center, NE Reduced sulfur emissions and feeding distillers byproducts
- 2. 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
- 3. 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 Sulfides Rumen Bacteria
- 4. Research Questions Q: How does diet effect sulfur emissions? Q: Where are cattle feedlot pen ‘hot spots’? Q: Sulfur sources: manure or soil?
- 5. 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
- 6. 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 ( g/g DM) 1.57a 3.07a 8.85b 16.41c 0.88 Varel et al., JEQ 2008
- 7. 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)
- 8. Three highest values averaged & background subtracted TRS Emission Profile Pen 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,ppm Manure Added Manure Removed
- 9. • Feeding >20% wet distillers increases H2S emission. • Similar result for large-scale feedlot? WDGS Study #1 WDGS Study #1 0.00 0.50 1.00 1.50 2.00 2.50 3.00 0 20 40 60 Percentage Wet Distillers Grains TotalReducedSulfur,ppm 8/20/2007 9/24/2007 10/22/2007 a a a a b b b c a a b c
- 10. 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
- 11. 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,ppm 0% 40% P = 0.001 P = 0.079 P = 0.002 P = 0.088
- 12. WDGS Study #2b (Post Production—Lingering Effects?) • Four pens (2 WDGS, 2 DRC) • Utilize EC to select 20 sites per pen Represent entire surface Classified sites as ‘Mound’ or ‘Edge’ • Measure H2S flux with chambers • Collected soil samples for analysis Moisture content Organic matter content
- 14. 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
- 15. WDGS Study #3 Multi-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
- 16. WDGS Study #3 Relative TRS emission • WDGS flux 0.3 to 4-fold higher on 5 of 7 dates.
- 17. WDGS Study #3 Edge versus Mound • Larger relative emission in control diet. • WDGS consistent but not significant Diet Mound Edge WDGS 3.35 5.56 Control 2.21A 2.99B T-test 0.001 0.028
- 18. Research Questions Q: Diet? Q: Location?Q: Source? A: 40% WDGS increases TRS. A: Pen edges more important than mound A: Manure strongest source.
- 19. 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?
- 20. Questions?