{"id":{"repo_id":"umn","oai_identifier":"oai:conservancy.umn.edu:11299/278025"},"canonical_url":"https://search.dev.ndltd.org/etd/umn/oai:conservancy.umn.edu:11299/278025","repository":{"repo_id":"umn","name":"University of Minnesota","base_url":"https://conservancy.umn.edu/server/oai/request"},"display":{"title":"Dialing in the most corn-profitable and environmentally responsible nitrogen rate","abstract":"Efficient nitrogen (N) management is essential for optimizing corn (Zea mays L.) productivity while minimizing environmental N losses in subsurface-drained continuous corn (CC) systems. This three-year study (2021 – 2023) at the Southwest Research and Outreach Center (SWROC) in Lamberton, Minnesota evaluated agronomic responses and environmental N losses across five N rates (0 – 360 kg N ha-1) using N best management practices (N-BMPs) including timing (in-season split application), placement (incorporation with tillage of pre-plant fertilizer), and source [enhanced efficiency fertilizers: polymer coated urea (ESN) and urea treated with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT)]. Measurements included grain yield, plant total N uptake (TNU), soil total inorganic N (TIN) at various depths within the top 90 cm, canopy sensing for N management, and N loss measurements of nitrate (NO3-N) leaching, ammonia (NH3-N) volatilization, and nitrous oxide (N2O-N) emissions. The mean economic optimum N rate (EONR) was 173 kg N ha-1, with a coefficient of variation (CV) of 23%, corresponding to an optimum range of 133 to 213 kg N ha-1. Above this threshold, yield gains plateaued or declined while residual soil N, N2O-N emissions, and NO3-N leaching increased linearly, indicating declining N use efficiency (NUE) and increased environmental risk. At 25% above the mean EONR, total N loss was estimated at 24.6 kg N ha-1, with NO3-N leaching accounting for 86% of the total, compared to only a 3% yield gain. This illustrates the disproportionate rise in environmental loss relative to agronomic benefit. Ammonia volatilization was most prominent in 2021 and influenced primarily by dry surface conditions rather than N rate. Nitrous oxide emissions peaked in 2022, because early-season rainfall events and waterlogging coincided with high surface N accumulation from prior dry conditions. Nitrate leaching dominated in 2023 due to frequent early-season precipitation and drainage. This sequence shows that timing and intensity of precipitation, not only total rainfall, critically shaped dominant N loss pathways. When one loss pathway increased, another often declined, revealing tradeoffs and demonstrating the interconnected nature of N loss mechanisms and the need for integrated management practices. Managing N inputs within a flexible EONR range provides a practical strategy to maintain yield and mitigate environmental losses across variable growing conditions. This study highlights the value of concurrently measuring multiple N loss pathways and supports season-specific adaptive strategies to reduce the environmental footprint of intensive CC production.","abstract_html":"Efficient nitrogen (N) management is essential for optimizing corn (Zea mays L.) productivity while minimizing environmental N losses in subsurface-drained continuous corn (CC) systems. This three-year study (2021 – 2023) at the Southwest Research and Outreach Center (SWROC) in Lamberton, Minnesota evaluated agronomic responses and environmental N losses across five N rates (0 – 360 kg N ha-1) using N best management practices (N-BMPs) including timing (in-season split application), placement (incorporation with tillage of pre-plant fertilizer), and source [enhanced efficiency fertilizers: polymer coated urea (ESN) and urea treated with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT)]. Measurements included grain yield, plant total N uptake (TNU), soil total inorganic N (TIN) at various depths within the top 90 cm, canopy sensing for N management, and N loss measurements of nitrate (NO3-N) leaching, ammonia (NH3-N) volatilization, and nitrous oxide (N2O-N) emissions. The mean economic optimum N rate (EONR) was 173 kg N ha-1, with a coefficient of variation (CV) of 23%, corresponding to an optimum range of 133 to 213 kg N ha-1. Above this threshold, yield gains plateaued or declined while residual soil N, N2O-N emissions, and NO3-N leaching increased linearly, indicating declining N use efficiency (NUE) and increased environmental risk. At 25% above the mean EONR, total N loss was estimated at 24.6 kg N ha-1, with NO3-N leaching accounting for 86% of the total, compared to only a 3% yield gain. This illustrates the disproportionate rise in environmental loss relative to agronomic benefit. Ammonia volatilization was most prominent in 2021 and influenced primarily by dry surface conditions rather than N rate. Nitrous oxide emissions peaked in 2022, because early-season rainfall events and waterlogging coincided with high surface N accumulation from prior dry conditions. Nitrate leaching dominated in 2023 due to frequent early-season precipitation and drainage. This sequence shows that timing and intensity of precipitation, not only total rainfall, critically shaped dominant N loss pathways. When one loss pathway increased, another often declined, revealing tradeoffs and demonstrating the interconnected nature of N loss mechanisms and the need for integrated management practices. Managing N inputs within a flexible EONR range provides a practical strategy to maintain yield and mitigate environmental losses across variable growing conditions. This study highlights the value of concurrently measuring multiple N loss pathways and supports season-specific adaptive strategies to reduce the environmental footprint of intensive CC production.","abstract_has_math":false,"creators":["Aanerud, Zachary"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-05","date_published":"2025-05","updated_at":"2026-07-24T05:19:58Z","subjects":["Ammonia","Corn","Drainage","Nitrate","Nitrogen","Nitrous Oxide"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/11299/278025","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Aanerud, Zachary"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-02-03T19:57:03Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-05"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Ammonia","Corn","Drainage","Nitrate","Nitrogen","Nitrous Oxide"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/11299/278025"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["University of Minnesota Ph.D. dissertation. May 2025. Major: Water Resources Science. Advisor: Fabian Fernandez. 1 computer file (PDF); x, 74 pages."]},{"key":"dc:description.abstract","label":"Abstract","values":["Efficient nitrogen (N) management is essential for optimizing corn (Zea mays L.) productivity while minimizing environmental N losses in subsurface-drained continuous corn (CC) systems. This three-year study (2021 – 2023) at the Southwest Research and Outreach Center (SWROC) in Lamberton, Minnesota evaluated agronomic responses and environmental N losses across five N rates (0 – 360 kg N ha-1) using N best management practices (N-BMPs) including timing (in-season split application), placement (incorporation with tillage of pre-plant fertilizer), and source [enhanced efficiency fertilizers: polymer coated urea (ESN) and urea treated with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT)]. Measurements included grain yield, plant total N uptake (TNU), soil total inorganic N (TIN) at various depths within the top 90 cm, canopy sensing for N management, and N loss measurements of nitrate (NO3-N) leaching, ammonia (NH3-N) volatilization, and nitrous oxide (N2O-N) emissions. The mean economic optimum N rate (EONR) was 173 kg N ha-1, with a coefficient of variation (CV) of 23%, corresponding to an optimum range of 133 to 213 kg N ha-1. Above this threshold, yield gains plateaued or declined while residual soil N, N2O-N emissions, and NO3-N leaching increased linearly, indicating declining N use efficiency (NUE) and increased environmental risk. At 25% above the mean EONR, total N loss was estimated at 24.6 kg N ha-1, with NO3-N leaching accounting for 86% of the total, compared to only a 3% yield gain. This illustrates the disproportionate rise in environmental loss relative to agronomic benefit. Ammonia volatilization was most prominent in 2021 and influenced primarily by dry surface conditions rather than N rate. Nitrous oxide emissions peaked in 2022, because early-season rainfall events and waterlogging coincided with high surface N accumulation from prior dry conditions. Nitrate leaching dominated in 2023 due to frequent early-season precipitation and drainage. This sequence shows that timing and intensity of precipitation, not only total rainfall, critically shaped dominant N loss pathways. When one loss pathway increased, another often declined, revealing tradeoffs and demonstrating the interconnected nature of N loss mechanisms and the need for integrated management practices. Managing N inputs within a flexible EONR range provides a practical strategy to maintain yield and mitigate environmental losses across variable growing conditions. This study highlights the value of concurrently measuring multiple N loss pathways and supports season-specific adaptive strategies to reduce the environmental footprint of intensive CC production."]},{"key":"dc:title","label":"Title","values":["Dialing in the most corn-profitable and environmentally responsible nitrogen rate"]}]}],"canonical_facts":{"dc:creator":["Aanerud, Zachary"],"dc:date.accessioned":["2026-02-03T19:57:03Z"],"dc:date.issued":["2025-05"],"dc:description":["University of Minnesota Ph.D. dissertation. May 2025. Major: Water Resources Science. Advisor: Fabian Fernandez. 1 computer file (PDF); x, 74 pages."],"dc:description.abstract":["Efficient nitrogen (N) management is essential for optimizing corn (Zea mays L.) productivity while minimizing environmental N losses in subsurface-drained continuous corn (CC) systems. This three-year study (2021 – 2023) at the Southwest Research and Outreach Center (SWROC) in Lamberton, Minnesota evaluated agronomic responses and environmental N losses across five N rates (0 – 360 kg N ha-1) using N best management practices (N-BMPs) including timing (in-season split application), placement (incorporation with tillage of pre-plant fertilizer), and source [enhanced efficiency fertilizers: polymer coated urea (ESN) and urea treated with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT)]. Measurements included grain yield, plant total N uptake (TNU), soil total inorganic N (TIN) at various depths within the top 90 cm, canopy sensing for N management, and N loss measurements of nitrate (NO3-N) leaching, ammonia (NH3-N) volatilization, and nitrous oxide (N2O-N) emissions. The mean economic optimum N rate (EONR) was 173 kg N ha-1, with a coefficient of variation (CV) of 23%, corresponding to an optimum range of 133 to 213 kg N ha-1. Above this threshold, yield gains plateaued or declined while residual soil N, N2O-N emissions, and NO3-N leaching increased linearly, indicating declining N use efficiency (NUE) and increased environmental risk. At 25% above the mean EONR, total N loss was estimated at 24.6 kg N ha-1, with NO3-N leaching accounting for 86% of the total, compared to only a 3% yield gain. This illustrates the disproportionate rise in environmental loss relative to agronomic benefit. Ammonia volatilization was most prominent in 2021 and influenced primarily by dry surface conditions rather than N rate. Nitrous oxide emissions peaked in 2022, because early-season rainfall events and waterlogging coincided with high surface N accumulation from prior dry conditions. Nitrate leaching dominated in 2023 due to frequent early-season precipitation and drainage. This sequence shows that timing and intensity of precipitation, not only total rainfall, critically shaped dominant N loss pathways. When one loss pathway increased, another often declined, revealing tradeoffs and demonstrating the interconnected nature of N loss mechanisms and the need for integrated management practices. Managing N inputs within a flexible EONR range provides a practical strategy to maintain yield and mitigate environmental losses across variable growing conditions. This study highlights the value of concurrently measuring multiple N loss pathways and supports season-specific adaptive strategies to reduce the environmental footprint of intensive CC production."],"dc:identifier.uri":["https://hdl.handle.net/11299/278025"],"dc:language.iso":["en"],"dc:subject":["Ammonia","Corn","Drainage","Nitrate","Nitrogen","Nitrous Oxide"],"dc:title":["Dialing in the most corn-profitable and environmentally responsible nitrogen rate"],"dc:type":["Thesis or Dissertation"]},"updated_at":"2026-07-24T05:19:58Z"}