The Environmental Protection Agency (EPA) currently uses a single methane (CH4) emissions factor of 160 kg CH4-C ha-1 for a primary rice (Oryza sativa L.) crop. The emissions factor is based on studies that do not adequately represent current management practices in Arkansas. Another concern is pre-flood fertilizer nitrogen (N) management, as the common N source, urea, is prone to loss via ammonia (NH3) volatilization. Thus, the objective of this research was to investigate trace gas emissions from rice on a silt-loam soil, including CH4 emissions as influenced by nitrogen (N) fertilization (i.e., optimal N and no N) in 2011, and previous crop [i.e., soybean (Glycine max L.) or rice] and cultivar (i.e., semi-dwarf, standard-stature, and hybrid) in 2012, and to assess the impact on grain yield of ammonia (NH3) volatilization from preflood urea application with and without the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). A chamber-based method was used to measure methane fluxes and linear interpolation and numerical integration between individual sample dates was performed to determine seasonal emissions. Ammonia volatilization was measured using semi-open static chambers. In 2011, no differences (P > 0.05) were measured in CH4 emissions due to N fertilization where mean annual emissions were 195 kg CH4-C ha-1. Methane emissions in 2012 were greater (P < 0.05) when rice was the previous crop (184 kg CH4-C ha-1) compared to when soybean was the previous crop (127 kg CH4-C ha-1), and emissions were greater from the semi-dwarf pure-line cultivar (169 kg CH4-C ha-1) and standard-stature pure-line cultivars (186 kg CH4-C ha-1), which did not differ, compared to the hybrid cultivar (111 kg CH4-C ha-1). Ammonia volatilization was reduced (P < 0.05) and grain yield increased when using NBPT compared to untreated urea. Methane results suggest the EPA's emissions factor potentially overestimates CH4 emissions in Arkansas, as 70% of rice production follows soybean and 50%
of production is from hybrid rice. Results also indicate NH3 volatilization can be reduced by the usage of NBPT. Thus, trace gas emissions measurements from rice will improve long-term sustainability assessments of rice.
","abstract_html":"<p>The Environmental Protection Agency (EPA) currently uses a single methane (CH4) emissions factor of 160 kg CH4-C ha-1 for a primary rice (Oryza sativa L.) crop. The emissions factor is based on studies that do not adequately represent current management practices in Arkansas. Another concern is pre-flood fertilizer nitrogen (N) management, as the common N source, urea, is prone to loss via ammonia (NH3) volatilization. Thus, the objective of this research was to investigate trace gas emissions from rice on a silt-loam soil, including CH4 emissions as influenced by nitrogen (N) fertilization (i.e., optimal N and no N) in 2011, and previous crop [i.e., soybean (Glycine max L.) or rice] and cultivar (i.e., semi-dwarf, standard-stature, and hybrid) in 2012, and to assess the impact on grain yield of ammonia (NH3) volatilization from preflood urea application with and without the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). A chamber-based method was used to measure methane fluxes and linear interpolation and numerical integration between individual sample dates was performed to determine seasonal emissions. Ammonia volatilization was measured using semi-open static chambers. In 2011, no differences (P > 0.05) were measured in CH4 emissions due to N fertilization where mean annual emissions were 195 kg CH4-C ha-1. Methane emissions in 2012 were greater (P < 0.05) when rice was the previous crop (184 kg CH4-C ha-1) compared to when soybean was the previous crop (127 kg CH4-C ha-1), and emissions were greater from the semi-dwarf pure-line cultivar (169 kg CH4-C ha-1) and standard-stature pure-line cultivars (186 kg CH4-C ha-1), which did not differ, compared to the hybrid cultivar (111 kg CH4-C ha-1). Ammonia volatilization was reduced (P < 0.05) and grain yield increased when using NBPT compared to untreated urea. Methane results suggest the EPA's emissions factor potentially overestimates CH4 emissions in Arkansas, as 70% of rice production follows soybean and 50% </p> <p>of production is from hybrid rice. Results also indicate NH3 volatilization can be reduced by the usage of NBPT. Thus, trace gas emissions measurements from rice will improve long-term sustainability assessments of rice. </p>","abstract_has_math":false,"creators":["Rogers, Christopher Wade"],"institution":null,"degree_name":"Doctor of Philosophy in Crop, Soil & Environmental Sciences (PhD)","degree_level":"Dissertation","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Brye, Kristofor R.","Evans-White, Michelle A."],"advisors":["Norman, Richard J."],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-05-01T07:00:00Z","date_published":"2014-05-01T07:00:00Z","updated_at":"2026-07-24T00:58:44Z","subjects":["Ammonia Volatilization","Methane","Rice","Trace Gases","Agronomy and Crop Sciences","Biogeochemistry"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.uark.edu/etd/2355","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Brye, Kristofor R.","Evans-White, Michelle A."]},{"key":"dc:contributor.advisor","label":"Advisor","values":["Norman, Richard J."]},{"key":"dc:creator","label":"Author","values":["Rogers, Christopher Wade"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2018-08-22T07:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy in Crop, Soil & Environmental Sciences (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Ammonia Volatilization","Methane","Rice","Trace Gases","Agronomy and Crop Sciences","Biogeochemistry"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarworks.uark.edu/etd/2355"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The Environmental Protection Agency (EPA) currently uses a single methane (CH4) emissions factor of 160 kg CH4-C ha-1 for a primary rice (Oryza sativa L.) crop. The emissions factor is based on studies that do not adequately represent current management practices in Arkansas. Another concern is pre-flood fertilizer nitrogen (N) management, as the common N source, urea, is prone to loss via ammonia (NH3) volatilization. Thus, the objective of this research was to investigate trace gas emissions from rice on a silt-loam soil, including CH4 emissions as influenced by nitrogen (N) fertilization (i.e., optimal N and no N) in 2011, and previous crop [i.e., soybean (Glycine max L.) or rice] and cultivar (i.e., semi-dwarf, standard-stature, and hybrid) in 2012, and to assess the impact on grain yield of ammonia (NH3) volatilization from preflood urea application with and without the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). A chamber-based method was used to measure methane fluxes and linear interpolation and numerical integration between individual sample dates was performed to determine seasonal emissions. Ammonia volatilization was measured using semi-open static chambers. In 2011, no differences (P > 0.05) were measured in CH4 emissions due to N fertilization where mean annual emissions were 195 kg CH4-C ha-1. Methane emissions in 2012 were greater (P < 0.05) when rice was the previous crop (184 kg CH4-C ha-1) compared to when soybean was the previous crop (127 kg CH4-C ha-1), and emissions were greater from the semi-dwarf pure-line cultivar (169 kg CH4-C ha-1) and standard-stature pure-line cultivars (186 kg CH4-C ha-1), which did not differ, compared to the hybrid cultivar (111 kg CH4-C ha-1). Ammonia volatilization was reduced (P < 0.05) and grain yield increased when using NBPT compared to untreated urea. Methane results suggest the EPA's emissions factor potentially overestimates CH4 emissions in Arkansas, as 70% of rice production follows soybean and 50%
of production is from hybrid rice. Results also indicate NH3 volatilization can be reduced by the usage of NBPT. Thus, trace gas emissions measurements from rice will improve long-term sustainability assessments of rice.
"]},{"key":"dc:title","label":"Title","values":["Methane Emissions and Ammonia Volatilization from Drill-Seeded, Delayed-Flood Rice on a Silt-Loam Soil in Arkansas"]}]}],"canonical_facts":{"dc:contributor":["Brye, Kristofor R.","Evans-White, Michelle A."],"dc:contributor.advisor":["Norman, Richard J."],"dc:creator":["Rogers, Christopher Wade"],"dc:date":["2014"],"dc:date.available":["2018-08-22T07:00:00Z"],"dc:description.abstract":["The Environmental Protection Agency (EPA) currently uses a single methane (CH4) emissions factor of 160 kg CH4-C ha-1 for a primary rice (Oryza sativa L.) crop. The emissions factor is based on studies that do not adequately represent current management practices in Arkansas. Another concern is pre-flood fertilizer nitrogen (N) management, as the common N source, urea, is prone to loss via ammonia (NH3) volatilization. Thus, the objective of this research was to investigate trace gas emissions from rice on a silt-loam soil, including CH4 emissions as influenced by nitrogen (N) fertilization (i.e., optimal N and no N) in 2011, and previous crop [i.e., soybean (Glycine max L.) or rice] and cultivar (i.e., semi-dwarf, standard-stature, and hybrid) in 2012, and to assess the impact on grain yield of ammonia (NH3) volatilization from preflood urea application with and without the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). A chamber-based method was used to measure methane fluxes and linear interpolation and numerical integration between individual sample dates was performed to determine seasonal emissions. Ammonia volatilization was measured using semi-open static chambers. In 2011, no differences (P > 0.05) were measured in CH4 emissions due to N fertilization where mean annual emissions were 195 kg CH4-C ha-1. Methane emissions in 2012 were greater (P < 0.05) when rice was the previous crop (184 kg CH4-C ha-1) compared to when soybean was the previous crop (127 kg CH4-C ha-1), and emissions were greater from the semi-dwarf pure-line cultivar (169 kg CH4-C ha-1) and standard-stature pure-line cultivars (186 kg CH4-C ha-1), which did not differ, compared to the hybrid cultivar (111 kg CH4-C ha-1). Ammonia volatilization was reduced (P < 0.05) and grain yield increased when using NBPT compared to untreated urea. Methane results suggest the EPA's emissions factor potentially overestimates CH4 emissions in Arkansas, as 70% of rice production follows soybean and 50%
of production is from hybrid rice. Results also indicate NH3 volatilization can be reduced by the usage of NBPT. Thus, trace gas emissions measurements from rice will improve long-term sustainability assessments of rice.
"],"dc:identifier":["https://scholarworks.uark.edu/etd/2355"],"dc:subject":["Ammonia Volatilization","Methane","Rice","Trace Gases","Agronomy and Crop Sciences","Biogeochemistry"],"dc:title":["Methane Emissions and Ammonia Volatilization from Drill-Seeded, Delayed-Flood Rice on a Silt-Loam Soil in Arkansas"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy in Crop, Soil & Environmental Sciences (PhD)"]},"updated_at":"2026-07-24T00:58:44Z"}