Proceedings available at: http://www.extension.org/67670 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

1. Drying and Rewetting Effects on Gas Emissions from Dairy Manure in Semi-arid Regions
Pakorn Sutitarnnontr1 (pakorn@aggiemail.usu.edu), Enzhu Hu1, Rhonda Miller2, Markus Tuller3, and Scott B. Jones1
1. Department of Plants, Soils and Climate, Utah State University, Logan, Utah
2. Agricultural Systems Technology and Education Department, Utah State University, Logan, Utah
3. Department of Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona
Introduction
Acknowledgments
The major source of gaseous emissions from animal
production sites is animal waste (manure) in solid, slurry,
or liquid forms, exhibiting varying physical properties.
Once manure is excreted from an animal, processes of
biological decomposition and formation of gaseous
compounds continue, but diminish as manure cools and
dries. Animal manure and its common use as fertilizer
contribute to gaseous emissions, significantly degrading
air quality to the detriment of human health and the
environment. Changes in gas emissions during drying and
following rewetting, particularly from precipitation, have
been observed in various agricultural settings.
Our study investigates changes of gaseous emissions
from manure-incorporated soils undergoing drying and
rewetting processes to identify the effects of climatic
conditions and manure management. The rewetting of
dry manure-incorporated soil represents abrupt step
changes in physical soil conditions, particularly changes
in moisture content. We dried and rewetted dairy
manure-incorporated soil in a greenhouse to maintain
moderate summertime temperatures (15 - 40 oC), while
monitoring gaseous emissions throughout these
processes. Closed dynamic chambers (CDC) coupled with
a multiplexed Fourier Transformed Infrared (FTIR)
spectroscopy gas analyzer provided gas flux estimates.
The results from our study will be used to advance
development of appropriate best management practices
to reduce gas emissions from dairy operations in semi-
arid regions.
The authors gratefully acknowledge
support from the USDA-NIFA under the
AFRI Air Quality Program (Grant # 2010-
85112-50524) and the Western Sustainable
Agriculture Research and Education
Program (Grant # GW13-006). Special
thanks go to Bill Mace for his assistance
with the experiments.
Dairy cattle on a typical feedlot (left). Animal waste, including
bedding materials such as straw from the feedlot, is commonly
collected and transported to a manure storage area (right) before
being applied as fertilizer.
A. GS3 Sensor Outputs (Volumetric Water
Content and Temperature)
Experimental Design and Setup
Results and Discussion
Soil water content,
temperature, and
electrical conductivity
were monitored using
GS3 Sensors (Decagon
Devices, Inc., Pullman,
WA).
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Temperature(oC)
Day
Our investigation was conducted at the USU
Research Greenhouse Complex (Logan, UT).
The average temperatures during day and
night times were 33 oC and 19 oC, respectively
(see below). The dairy farm yard manure with
straw bedding material, collected from the
Caine Dairy Teaching and Research Center
(Wellsville, UT), was applied and incorporated
into soil with an application rate of 50
ton/acre. Gas emissions were monitored from
the manure-incorporated soil using the CDC
technique with a multiplexed FTIR gas
analyzer. In addition, we examined changes in
moisture content throughout the experiment.
The Gasmet DX4030 FTIR gas analyzer
(Gasmet Technology Oy, Helsinki, Finland)
was capable of monitoring 15 pre-
programmed gases simultaneously, including
typical gaseous compounds and greenhouse
gases emitted from manure sources; namely,
ammonia (NH3), carbon dioxide (CO2),
methane (CH4), nitrous oxide (N2O), oxides of
nitrogen (NOx), and volatile organic
compounds (VOCs).
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VolumetricWaterContent(m3m-3)
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Volumetric Water Content (left axis)
Temperature (right axis) Rewetting Events
Drying Process Drying Process
Drying and rewetting events are important short-term
natural phenomenon in terms of hydrological cycling
within the soil-atmosphere system. We observed gas
emissions of CO2 (illustrated in Figures B) are influenced
substantially by these events. During drying, a strong
correlation was seen between gaseous emissions and
temperature and moisture content.
B. Gas Emissions (CO2 & NH3)
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CO2Flux(lbs/acre/hr)
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Rewetting
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CO2Flux(lbs/acre/hr)
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Rewetting
Gas emissions were suppressed during and shortly after the rewetting process, mainly due to reduction in air- filled pore space
causing reduced gas diffusivity in the upper soil layer. Emissions in response to rewetting events are critical for understanding of
carbon and nitrogen dynamics and land-atmosphere gas exchange.
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NH3Emission(lb/acre/hr)
CO2Emission(lbs/acre/hr)
Days
CO2 Emission (left axis)
NH3 Emission (right axis)