{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/124480"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/124480","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A quantitative evaluation of microbial interventions and biostimulant strategies in agricultural nitrogen management","abstract":"Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","abstract_html":"Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","abstract_has_math":false,"creators":["Klimasmith, Isaac Mowry"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Natural Res & Env Sciences","degree_department":null,"school":null,"contributors":["Kent, Angela D","Margenot, Andrew J","Below, Frederick E","Yang, Wendy","Ngumbi, Esther N"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-05","date_published":"2024-05","updated_at":"2026-07-22T22:25:02Z","subjects":["Microbial Ecology","Biosimulant","Nitrogen","Agriculture","Soil"],"languages":["en","eng"],"rights":["Copyright 2024 Isaac Klimasmith"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/124480","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Kent, Angela D","Margenot, Andrew J","Below, Frederick E","Yang, Wendy","Ngumbi, Esther N"]},{"key":"dc:creator","label":"Author","values":["Klimasmith, Isaac Mowry"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2024-05","2023-12-20"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Natural Res & Env Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Microbial Ecology","Biosimulant","Nitrogen","Agriculture","Soil"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2024 Isaac Klimasmith"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/124480"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","The student, Isaac Klimasmith, accepted the attached license on 2023-12-19 at 16:18.","The student, Isaac Klimasmith, submitted this Dissertation for approval on 2023-12-19 at 16:23.","This Dissertation was approved for publication on 2023-12-20 at 09:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #20193 on 2024-09-16 at 00:41:55","In response to the dual challenges of global population growth and environmental degradation, scientific and commercial focus on biostimulants as a possible route toward sustainable agricultural intensification has recently increased. In this dissertation, my work focuses on two types of biostimulants: nitrogen-fixing microbial inoculants and seaweed extracts. Microbial inoculants are applied to make diazotrophic bacteria more abundant in the soil, offering the tantalizing promise of maintaining crop productivity in the face of climate change while reducing dependence on synthetic fertilizers. Seaweed extracts are rich in carbon and micronutrients and can improve crop stress resistance, yield, and nutrient acquisition. While both classes of biostimulants have the potential to interact with the carbon and nitrogen cycles within the soil, relatively little attention has been paid to the impact of biostimulants on soil microbial communities and the nitrogen transformations they facilitate. Understanding these dynamics is vital to sustainably deploying biostimulants, as prior studies have shown that some biostimulants can exacerbate agricultural nitrogen pollution. The first three studies presented here quantify the impact of biostimulant addition on the microbial nitrogen cycle in maize agriculture. While seaweed extract addition appears to have little effect on microbial nitrogen cycling, nitrogen cycling outcomes under nitrogen-fixing inoculant addition shift depending on fertilizer application rate and in-furrow carbon addition. Overall, inoculant application alone can mildly exacerbate nitrification and denitrification in higher fertilizer conditions. However, these outcomes shift towards lower rates of nitrification and denitrification when the inoculant is paired with an intermediate fertilizer rate or in-furrow carbon. Across the growing season, the treatment effect of inoculant addition declines, suggesting that these bacteria struggle to survive and persist in the soil community. To investigate practices that can improve inoculant persistence, I applied propagule pressure models developed for invasion ecology to microbial introductions. Based on inoculant persistence in a greenhouse study, these models predict that more frequent application (increased propagule number) but not increased inoculant concentration (propagule size) can raise the establishment probability of microbial inoculants. Together, these studies contribute to our understanding of biostimulants not as static inputs, but as interactive components of dynamic agroecosystems."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["A quantitative evaluation of microbial interventions and biostimulant strategies in agricultural nitrogen management"]}]}],"canonical_facts":{"dc:contributor":["Kent, Angela D","Margenot, Andrew J","Below, Frederick E","Yang, Wendy","Ngumbi, Esther N"],"dc:creator":["Klimasmith, Isaac Mowry"],"dc:date":["2024-05","2023-12-20"],"dc:description":["Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","The student, Isaac Klimasmith, accepted the attached license on 2023-12-19 at 16:18.","The student, Isaac Klimasmith, submitted this Dissertation for approval on 2023-12-19 at 16:23.","This Dissertation was approved for publication on 2023-12-20 at 09:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #20193 on 2024-09-16 at 00:41:55","In response to the dual challenges of global population growth and environmental degradation, scientific and commercial focus on biostimulants as a possible route toward sustainable agricultural intensification has recently increased. In this dissertation, my work focuses on two types of biostimulants: nitrogen-fixing microbial inoculants and seaweed extracts. Microbial inoculants are applied to make diazotrophic bacteria more abundant in the soil, offering the tantalizing promise of maintaining crop productivity in the face of climate change while reducing dependence on synthetic fertilizers. Seaweed extracts are rich in carbon and micronutrients and can improve crop stress resistance, yield, and nutrient acquisition. While both classes of biostimulants have the potential to interact with the carbon and nitrogen cycles within the soil, relatively little attention has been paid to the impact of biostimulants on soil microbial communities and the nitrogen transformations they facilitate. Understanding these dynamics is vital to sustainably deploying biostimulants, as prior studies have shown that some biostimulants can exacerbate agricultural nitrogen pollution. The first three studies presented here quantify the impact of biostimulant addition on the microbial nitrogen cycle in maize agriculture. While seaweed extract addition appears to have little effect on microbial nitrogen cycling, nitrogen cycling outcomes under nitrogen-fixing inoculant addition shift depending on fertilizer application rate and in-furrow carbon addition. Overall, inoculant application alone can mildly exacerbate nitrification and denitrification in higher fertilizer conditions. However, these outcomes shift towards lower rates of nitrification and denitrification when the inoculant is paired with an intermediate fertilizer rate or in-furrow carbon. Across the growing season, the treatment effect of inoculant addition declines, suggesting that these bacteria struggle to survive and persist in the soil community. To investigate practices that can improve inoculant persistence, I applied propagule pressure models developed for invasion ecology to microbial introductions. Based on inoculant persistence in a greenhouse study, these models predict that more frequent application (increased propagule number) but not increased inoculant concentration (propagule size) can raise the establishment probability of microbial inoculants. Together, these studies contribute to our understanding of biostimulants not as static inputs, but as interactive components of dynamic agroecosystems."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/124480"],"dc:language":["en","eng"],"dc:rights":["Copyright 2024 Isaac Klimasmith"],"dc:subject":["Microbial Ecology","Biosimulant","Nitrogen","Agriculture","Soil"],"dc:title":["A quantitative evaluation of microbial interventions and biostimulant strategies in agricultural nitrogen management"],"dc:type":["text"],"thesis:degree_discipline":["Natural Res & Env Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:02Z"}