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Drying and Rewetting Effects on Gas Emissions from Dairy Manure in Semi-arid Regions


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The major source of emissions in animal production sites is from animal waste (manure), which can be in solid, slurry, or liquid states, exhibiting varying physical properties. Once manure is excreted from an animal, processes of biological decomposition and formation of gaseous compounds continue, but diminish as the manure cools and dries. However, increases in gas emissions following rewetting, particularly from precipitation, have been observed in various agricultural lands. Our study investigates changes of gaseous emissions through manure drying and rewetting processes to identify the effects of climatic conditions and manure management on gaseous emissions. We carried out drying and rewetting processes of dairy manure in a greenhouse to maintain moderate wintertime temperatures (20 - 40 C) while monitoring gaseous emissions through these processes. Closed dynamic chambers (CDC) coupled with a multiplexed Fourier Transformed Infrared (FTIR) spectroscopy gas analyzer provided gas flux estimates. The analyzer was capable of monitoring 15 pre-programmed gases simultaneously including typical gaseous compounds and greenhouse gases emitted from manure sources; namely, ammonia, carbon dioxide, methane, nitrous oxide, oxides of nitrogen, and volatile organic compounds. Magnitude of dairy manure gas emissions resulting from variations in moisture and temperature provide insight toward enhancing manure management decisions. Results from our study should further understanding of manure gas emission temporal dynamics that are largely dictated by heat and by drying and rewetting processes that impact the generation and delivery of gasses to the atmosphere. Our overall goal is to advance development of appropriate best management practices to reduce gas emissions for dairy operations in semi-arid regions.

Presented by: Pakorn Sutitarnnontr

Published in: Education
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Drying and Rewetting Effects on Gas Emissions from Dairy Manure in Semi-arid Regions

  1. 1. Drying and Rewetting Effects on Gas Emissions from Dairy Manure in Semi-arid RegionsPakorn Sutitarnnontr1 (, Enzhu Hu1, Rhonda Miller2, Markus Tuller3, and Scott B. Jones11. Department of Plants, Soils and Climate, Utah State University, Logan, Utah2. Agricultural Systems Technology and Education Department, Utah State University, Logan, Utah3. Department of Soil, Water, and Environmental Science, University of Arizona, Tucson, ArizonaIntroductionAcknowledgmentsThe major source of gaseous emissions from animalproduction sites is animal waste (manure) in solid, slurry,or liquid forms, exhibiting varying physical properties.Once manure is excreted from an animal, processes ofbiological decomposition and formation of gaseouscompounds continue, but diminish as manure cools anddries. Animal manure and its common use as fertilizercontribute to gaseous emissions, significantly degradingair quality to the detriment of human health and theenvironment. Changes in gas emissions during drying andfollowing rewetting, particularly from precipitation, havebeen observed in various agricultural settings.Our study investigates changes of gaseous emissionsfrom manure-incorporated soils undergoing drying andrewetting processes to identify the effects of climaticconditions and manure management. The rewetting ofdry manure-incorporated soil represents abrupt stepchanges in physical soil conditions, particularly changesin moisture content. We dried and rewetted dairymanure-incorporated soil in a greenhouse to maintainmoderate summertime temperatures (15 - 40 oC), whilemonitoring gaseous emissions throughout theseprocesses. Closed dynamic chambers (CDC) coupled witha multiplexed Fourier Transformed Infrared (FTIR)spectroscopy gas analyzer provided gas flux estimates.The results from our study will be used to advancedevelopment of appropriate best management practicesto reduce gas emissions from dairy operations in semi-arid regions.The authors gratefully acknowledgesupport from the USDA-NIFA under theAFRI Air Quality Program (Grant # 2010-85112-50524) and the Western SustainableAgriculture Research and EducationProgram (Grant # GW13-006). Specialthanks go to Bill Mace for his assistancewith the experiments.Dairy cattle on a typical feedlot (left). Animal waste, includingbedding materials such as straw from the feedlot, is commonlycollected and transported to a manure storage area (right) beforebeing applied as fertilizer.A. GS3 Sensor Outputs (Volumetric WaterContent and Temperature)Experimental Design and SetupResults and DiscussionSoil water content,temperature, andelectrical conductivitywere monitored usingGS3 Sensors (DecagonDevices, Inc., Pullman,WA).12 PM 12 PM 12 PM 12 PM 12 PM 12 PM 12 PM 12 PM101520253035400 1 2 3 4 5 6 7Temperature(oC)DayOur investigation was conducted at the USUResearch Greenhouse Complex (Logan, UT).The average temperatures during day andnight times were 33 oC and 19 oC, respectively(see below). The dairy farm yard manure withstraw bedding material, collected from theCaine Dairy Teaching and Research Center(Wellsville, UT), was applied and incorporatedinto soil with an application rate of 50ton/acre. Gas emissions were monitored fromthe manure-incorporated soil using the CDCtechnique with a multiplexed FTIR gasanalyzer. In addition, we examined changes inmoisture content throughout the experiment.The Gasmet DX4030 FTIR gas analyzer(Gasmet Technology Oy, Helsinki, Finland)was capable of monitoring 15 pre-programmed gases simultaneously, includingtypical gaseous compounds and greenhousegases emitted from manure sources; namely,ammonia (NH3), carbon dioxide (CO2),methane (CH4), nitrous oxide (N2O), oxides ofnitrogen (NOx), and volatile organiccompounds (VOCs).12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM0102030405060700. 1 2 3 4 5 6 7Temperature(oC)VolumetricWaterContent(m3m-3)DayVolumetric Water Content (left axis)Temperature (right axis) Rewetting EventsDrying Process Drying ProcessDrying and rewetting events are important short-termnatural phenomenon in terms of hydrological cyclingwithin the soil-atmosphere system. We observed gasemissions of CO2 (illustrated in Figures B) are influencedsubstantially by these events. During drying, a strongcorrelation was seen between gaseous emissions andtemperature and moisture content.B. Gas Emissions (CO2 & NH3)0 3 6 9 12 15 18 21 24024681012CO2Flux(lbs/acre/hr)HoursRewetting0 3 6 9 12 15 18 21 24024681012CO2Flux(lbs/acre/hr)HoursRewettingGas emissions were suppressed during and shortly after the rewetting process, mainly due to reduction in air- filled pore spacecausing reduced gas diffusivity in the upper soil layer. Emissions in response to rewetting events are critical for understanding ofcarbon and nitrogen dynamics and land-atmosphere gas exchange.12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM 12:00 PM1.E-061.E-051.E-041.E-031.E-021.E-0105101520250 1 2 3 4 5 6 7NH3Emission(lb/acre/hr)CO2Emission(lbs/acre/hr)DaysCO2 Emission (left axis)NH3 Emission (right axis)