The Experts below are selected from a list of 8253 Experts worldwide ranked by ideXlab platform
Birgir Norddahl - One of the best experts on this subject based on the ideXlab platform.
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Ammonium Fertilizers production from manure a critical review
Critical Reviews in Environmental Science and Technology, 2015Co-Authors: Agata Zarebska, Romero D Nieto, Knud Villy Christensen, Fjerbaek L Sotoft, Birgir NorddahlAbstract:Excessive livestock production in small areas poses a risk of nitrogen release to the environment and thus air and water contamination. Recovery of ammonia is necessary to avoid overfertilization, but manure management of untreated slurry is costly and complex. The authors discuss Ammonium fertilizer recovery from manure using membrane processes and physicochemical methods including technology and energy assessments. Currently, nanofiltration, reverse osmosis, membrane distillation combined with ultrafiltration, and air stripping are the best choices. The processes rely highly on selection of appropriate pretreatment, as residual particulates will lead to fouling of membranes and stripping towers hence affect the performance greatly.
Mussie Y Habteselassie - One of the best experts on this subject based on the ideXlab platform.
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ammonia oxidizing bacteria are more responsive than archaea to nitrogen source in an agricultural soil
Soil Biology & Biochemistry, 2016Co-Authors: Yang Ouyang, Jeanette M Norton, John M Stark, Jennifer R Reeve, Mussie Y HabteselassieAbstract:Abstract In the majority of agricultural soils, Ammonium (NH 4 + ) is rapidly converted to nitrate (NO 3 − ) in the biological ammonia and nitrite oxidation processes known as nitrification. The often rate-limiting step of ammonia oxidation to nitrite is mediated by ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA). The response of AOA and AOB communities to organic and conventional nitrogen (N) Fertilizers, and their relative contributions to the nitrification process were examined for an agricultural silage corn system using a randomized block design with 4 N treatments: control (no additional N), Ammonium sulfate (AS) fertilizer at 100 and 200 kg N ha −1 , and steer-waste compost (200 kg total N ha −1 ) over four seasons. DNA was extracted from the soil, and real-time PCR and 454-pyrosequencing were used to evaluate the quantity and diversity of the amoA gene which encodes subunit A of ammonia monooxygenase. Soil pH, nitrate pools, and nitrification potentials were influenced by Ammonium and organic Fertilizers after the first fertilization, while changes in AOB abundance and community structure were not apparent until after the second fertilization or later. The abundance of AOA was always greater than AOB but was unaffected by N treatments. In contrast, AOB abundance and community structure were changed significantly by Ammonium Fertilizers. Specific inhibitors of nitrification were used to evaluate the relative contribution of AOA and AOB to nitrification. We found that AOB dominantly contributed to potential nitrification activity determined at 1 mM Ammonium in soil slurries and nitrification potential activity was higher in soils treated with Ammonium Fertilizers relative to control soils. However, AOA dominated gross nitrification activity in moist soils. Our result suggests that AOB activity and community are more responsive to Ammonium Fertilizers than AOA, but that in situ nitrification rate is controlled by Ammonium availability in this agricultural soil. Understanding this response of AOA and AOB to N Fertilizers may contribute to improving strategies for the management of nitrate production in agricultural soils.
Ouyang Yang - One of the best experts on this subject based on the ideXlab platform.
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Short-Term Nitrogen Fertilization Affects Microbial Community Composition and Nitrogen Mineralization Function in an Agricultural Soil
Hosted by Utah State University Libraries, 2020Co-Authors: Ouyang Yang, Norton, Jeanette M.Abstract:Soil extracellular enzymes play a significant role in the N mineralization process. However, few studies have documented the linkage between enzyme activity and the microbial community that performs the function. This study examined the effects of inorganic and organic N fertilization on soil microbial communities and their N mineralization functions over 4 years. Soils were collected from silage corn field plots with four contrasting N treatments: control (no additional N), Ammonium sulfate (AS; 100 and 200 kg of N ha−1), and compost (200 kg of N ha−1). Illumina amplicon sequencing was used to comprehensively assess the overall bacterial community (16S rRNA genes), bacterial ureolytic community (ureC), and bacterial chitinolytic community (chiA). Selected genes involved in N mineralization were also examined using quantitative real-time PCR and metagenomics. Enzymes (and marker genes) included protease (npr and sub), chitinase (chiA), urease (ureC), and arginase (rocF). Compost significantly increased diversity of overall bacterial communities even after one application, while Ammonium Fertilizers had no influence on the overall bacterial communities over four seasons. Bacterial ureolytic and chitinolytic communities were significantly changed by N fertilization. Compost treatment strongly elevated soil enzyme activities after 4 years of repeated application. Functional gene abundances were not significantly affected by N treatments, and they were not correlated with corresponding enzyme activities. N mineralization genes were recovered from soil metagenomes based on a gene-targeted assembly. Understanding how the structure and function of soil microbial communities involved with N mineralization change in response to fertilization practices may indicate suitable agricultural management practices that improve ecosystem services while reducing negative environmental consequences
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Agricultural Nitrogen Management Affects Microbial Communities, Enzyme Activities, and Functional Genes for Nitrification and Nitrogen Mineralization
DigitalCommons@USU, 2016Co-Authors: Ouyang YangAbstract:The transformations of organic nitrogen to Ammonium and nitrate are central processes in the internal soil nitrogen cycle. In most agricultural soils, Ammonium is rapidly oxidized to nitrate in the process known as nitrification; often leading to loss of nitrate from the system. Nitrification is mediated by ammonia oxidizing bacteria or archaea, and nitrite oxidizing bacteria. Understanding links between process rates, enzyme activities and the communities of microbes that cycle nitrogen may contribute to sustainable management. Our main objective was to determine the impacts of contrasting nitrogen management on soil microbial communities, enzyme activities, and functional genes for nitrification and nitrogen mineralization in a Utah agricultural system. Process rates and activities were measured in laboratory potential assays and 15N isotope pool dilution experiments. The abundance and diversity of genes involved in nitrification and nitrogen mineralization were examined using quantitative real-time PCR, pyrosequencing, clone libraries, and metagenomics. Key enzymes and their relevant marker genes included ammonia monooxygenase (amoA), nitrite oxidoreductase (nxrB), protease (npr and sub), chitinase (chiA), and urease (ureC). The overall soil microbial community composition was assessed targeting ribosomal genes. Ammonia oxidizing bacteria were more responsive than archaea to Ammonium Fertilizers while the archaea were competitive under low Ammonium levels. The relative contribution of ammonia oxidizing archaea to nitrification increased with increasing temperature and their activity had a higher temperature optimum than bacteria. The abundance of ammonia oxidizers in the organic farming system increased with organic nitrogen Fertilizers and their activity was higher in manure than in compost treated soil. Nitrogen Fertilizers strongly stimulated the rates of potential nitrite oxidation. Nitrospira was the only known nitrite oxidizer genus recovered from any soil sample. The application of organic nitrogen Fertilizers, but not inorganic, increased the diversity of the prokaryotic community and the activities of soil enzymes. In the organic farming system, abundances of functional genes for mineralization were increased by organic nitrogen fertilizer and these abundances were significantly correlated with corresponding enzyme activity. Understanding the link between microbial communities and the biogeochemical functions of nitrification and mineralization may allow ecosystem models to incorporate microorganisms as dynamic components driving nitrogen flux
Agata Zarebska - One of the best experts on this subject based on the ideXlab platform.
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Ammonium Fertilizers production from manure a critical review
Critical Reviews in Environmental Science and Technology, 2015Co-Authors: Agata Zarebska, Romero D Nieto, Knud Villy Christensen, Fjerbaek L Sotoft, Birgir NorddahlAbstract:Excessive livestock production in small areas poses a risk of nitrogen release to the environment and thus air and water contamination. Recovery of ammonia is necessary to avoid overfertilization, but manure management of untreated slurry is costly and complex. The authors discuss Ammonium fertilizer recovery from manure using membrane processes and physicochemical methods including technology and energy assessments. Currently, nanofiltration, reverse osmosis, membrane distillation combined with ultrafiltration, and air stripping are the best choices. The processes rely highly on selection of appropriate pretreatment, as residual particulates will lead to fouling of membranes and stripping towers hence affect the performance greatly.
Yang Ouyang - One of the best experts on this subject based on the ideXlab platform.
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ammonia oxidizing bacteria are more responsive than archaea to nitrogen source in an agricultural soil
Soil Biology & Biochemistry, 2016Co-Authors: Yang Ouyang, Jeanette M Norton, John M Stark, Jennifer R Reeve, Mussie Y HabteselassieAbstract:Abstract In the majority of agricultural soils, Ammonium (NH 4 + ) is rapidly converted to nitrate (NO 3 − ) in the biological ammonia and nitrite oxidation processes known as nitrification. The often rate-limiting step of ammonia oxidation to nitrite is mediated by ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA). The response of AOA and AOB communities to organic and conventional nitrogen (N) Fertilizers, and their relative contributions to the nitrification process were examined for an agricultural silage corn system using a randomized block design with 4 N treatments: control (no additional N), Ammonium sulfate (AS) fertilizer at 100 and 200 kg N ha −1 , and steer-waste compost (200 kg total N ha −1 ) over four seasons. DNA was extracted from the soil, and real-time PCR and 454-pyrosequencing were used to evaluate the quantity and diversity of the amoA gene which encodes subunit A of ammonia monooxygenase. Soil pH, nitrate pools, and nitrification potentials were influenced by Ammonium and organic Fertilizers after the first fertilization, while changes in AOB abundance and community structure were not apparent until after the second fertilization or later. The abundance of AOA was always greater than AOB but was unaffected by N treatments. In contrast, AOB abundance and community structure were changed significantly by Ammonium Fertilizers. Specific inhibitors of nitrification were used to evaluate the relative contribution of AOA and AOB to nitrification. We found that AOB dominantly contributed to potential nitrification activity determined at 1 mM Ammonium in soil slurries and nitrification potential activity was higher in soils treated with Ammonium Fertilizers relative to control soils. However, AOA dominated gross nitrification activity in moist soils. Our result suggests that AOB activity and community are more responsive to Ammonium Fertilizers than AOA, but that in situ nitrification rate is controlled by Ammonium availability in this agricultural soil. Understanding this response of AOA and AOB to N Fertilizers may contribute to improving strategies for the management of nitrate production in agricultural soils.