{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/26166"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/26166","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Continuous No-till Management: Implications for Soil Quality, Carbon Sequestration, and Nitrogen Conservation","abstract":"No-till management for agronomic crop production is recognized as an effective practice to regain a portion of soil organic matter lost following decades of cultivation. Increasing soil organic matter sequesters C, conserves organic N and concomitantly improves soil quality. Objectives of this research were to: i) quantify C sequestration rate and N conservation with duration of continuous no-till; ii) measure C stratification with continuous no-till as an indicator of soil quality; and iii) evaluate the Illinois soil N test (ISNT) for its value to predict fertilizer N needs of corn in Virginia. Objectives i and ii were achieved by collecting soil samples from 63 production fields in the Virginia Coastal Plain that were managed using continuous no-till from 0 to 14 yrs. No-till management resulted in sequestration of 0.308 ± 0.280 Mg C ha⁻¹ y⁻¹ and conservation of 22.2 ± 21.2 kg N ha⁻¹ yr⁻¹ (0-15 cm). The C stratification ratio (0-2.5 cm: 7.5-15 cm) increased with increasing duration of continuous no-till (0.133 ± 0.056 yr⁻¹) due to the accumulation of organic matter at the soil surface indicating improved soil quality with continuous no-till management. Objective iii was addressed by conducting 29 on-farm fertilizer N response trials in major corn producing areas of Virginia with the duration of continuous no-till management ranging from 0 to 25 yrs. The ISNT values were significantly related to yield without fertilizer N (r² = 0.57; p<0.001) and relative yield (r² = 0.64; p<0.0001). We also found that the ISNT extracted a relatively consistent percentage of total soil N (16.3 ± 0.73 %) suggesting it is a poor indicator of labile N. Total soil N values did almost as well as the ISNT in predicting yield without fertilizer N (r² = 0.53; p = 0.0002), and equally well predicting relative yield (r² = 0.64; p<0.0001). Results do not suggest the ISNT is useful for measuring mineralizalbe N or improving fertilizer N recommendations in Virginia cropping systems.","abstract_html":"No-till management for agronomic crop production is recognized as an effective practice to regain a portion of soil organic matter lost following decades of cultivation. Increasing soil organic matter sequesters C, conserves organic N and concomitantly improves soil quality. Objectives of this research were to: i) quantify C sequestration rate and N conservation with duration of continuous no-till; ii) measure C stratification with continuous no-till as an indicator of soil quality; and iii) evaluate the Illinois soil N test (ISNT) for its value to predict fertilizer N needs of corn in Virginia. Objectives i and ii were achieved by collecting soil samples from 63 production fields in the Virginia Coastal Plain that were managed using continuous no-till from 0 to 14 yrs. No-till management resulted in sequestration of 0.308 ± 0.280 Mg C ha⁻¹ y⁻¹ and conservation of 22.2 ± 21.2 kg N ha⁻¹ yr⁻¹ (0-15 cm). The C stratification ratio (0-2.5 cm: 7.5-15 cm) increased with increasing duration of continuous no-till (0.133 ± 0.056 yr⁻¹) due to the accumulation of organic matter at the soil surface indicating improved soil quality with continuous no-till management. Objective iii was addressed by conducting 29 on-farm fertilizer N response trials in major corn producing areas of Virginia with the duration of continuous no-till management ranging from 0 to 25 yrs. The ISNT values were significantly related to yield without fertilizer N (r² = 0.57; p&lt;0.001) and relative yield (r² = 0.64; p&lt;0.0001). We also found that the ISNT extracted a relatively consistent percentage of total soil N (16.3 ± 0.73 %) suggesting it is a poor indicator of labile N. Total soil N values did almost as well as the ISNT in predicting yield without fertilizer N (r² = 0.53; p = 0.0002), and equally well predicting relative yield (r² = 0.64; p&lt;0.0001). Results do not suggest the ISNT is useful for measuring mineralizalbe N or improving fertilizer N recommendations in Virginia cropping systems.","abstract_has_math":false,"creators":["Spargo, John T."],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Crop and Soil Environmental Sciences","degree_department":"Crop and Soil Environmental Sciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Alley, Marcus M."],"committee_members":["Evanylo, Gregory K.","Follett, Ronald F.","Phillips, Steven B.","Zelazny, Lucian W."],"year":2008,"date_issued":"2008-02-01","date_published":"2008-02-01","updated_at":"2026-07-22T22:19:09Z","subjects":["Nitrogen use efficiency","carbon trading","nutrient trading","soil organic matter"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-02102008-174038"],"render_values":[{"text":"etd-02102008-174038","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/26166","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Alley, Marcus M."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Evanylo, Gregory K.","Follett, Ronald F.","Phillips, Steven B.","Zelazny, Lucian W."]},{"key":"dc:contributor.department","label":"Department","values":["Crop and Soil Environmental Sciences"]},{"key":"dc:creator","label":"Author","values":["Spargo, John T."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:07:17Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:07:17Z","2008-03-04"]},{"key":"dc:date.issued","label":"Date","values":["2008-02-01"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Crop and Soil Environmental Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. 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Increasing soil organic matter sequesters C, conserves organic N and concomitantly improves soil quality. Objectives of this research were to: i) quantify C sequestration rate and N conservation with duration of continuous no-till; ii) measure C stratification with continuous no-till as an indicator of soil quality; and iii) evaluate the Illinois soil N test (ISNT) for its value to predict fertilizer N needs of corn in Virginia. Objectives i and ii were achieved by collecting soil samples from 63 production fields in the Virginia Coastal Plain that were managed using continuous no-till from 0 to 14 yrs. No-till management resulted in sequestration of 0.308 ± 0.280 Mg C ha⁻¹ y⁻¹ and conservation of 22.2 ± 21.2 kg N ha⁻¹ yr⁻¹ (0-15 cm). The C stratification ratio (0-2.5 cm: 7.5-15 cm) increased with increasing duration of continuous no-till (0.133 ± 0.056 yr⁻¹) due to the accumulation of organic matter at the soil surface indicating improved soil quality with continuous no-till management. Objective iii was addressed by conducting 29 on-farm fertilizer N response trials in major corn producing areas of Virginia with the duration of continuous no-till management ranging from 0 to 25 yrs. The ISNT values were significantly related to yield without fertilizer N (r² = 0.57; p<0.001) and relative yield (r² = 0.64; p<0.0001). We also found that the ISNT extracted a relatively consistent percentage of total soil N (16.3 ± 0.73 %) suggesting it is a poor indicator of labile N. Total soil N values did almost as well as the ISNT in predicting yield without fertilizer N (r² = 0.53; p = 0.0002), and equally well predicting relative yield (r² = 0.64; p<0.0001). Results do not suggest the ISNT is useful for measuring mineralizalbe N or improving fertilizer N recommendations in Virginia cropping systems."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:title","label":"Title","values":["Continuous No-till Management: Implications for Soil Quality, Carbon Sequestration, and Nitrogen Conservation"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Alley, Marcus M."],"dc:contributor.committeemember":["Evanylo, Gregory K.","Follett, Ronald F.","Phillips, Steven B.","Zelazny, Lucian W."],"dc:contributor.department":["Crop and Soil Environmental Sciences"],"dc:creator":["Spargo, John T."],"dc:date.accessioned":["2014-03-14T20:07:17Z"],"dc:date.available":["2014-03-14T20:07:17Z","2008-03-04"],"dc:date.issued":["2008-02-01"],"dc:description.abstract":["No-till management for agronomic crop production is recognized as an effective practice to regain a portion of soil organic matter lost following decades of cultivation. Increasing soil organic matter sequesters C, conserves organic N and concomitantly improves soil quality. Objectives of this research were to: i) quantify C sequestration rate and N conservation with duration of continuous no-till; ii) measure C stratification with continuous no-till as an indicator of soil quality; and iii) evaluate the Illinois soil N test (ISNT) for its value to predict fertilizer N needs of corn in Virginia. Objectives i and ii were achieved by collecting soil samples from 63 production fields in the Virginia Coastal Plain that were managed using continuous no-till from 0 to 14 yrs. No-till management resulted in sequestration of 0.308 ± 0.280 Mg C ha⁻¹ y⁻¹ and conservation of 22.2 ± 21.2 kg N ha⁻¹ yr⁻¹ (0-15 cm). The C stratification ratio (0-2.5 cm: 7.5-15 cm) increased with increasing duration of continuous no-till (0.133 ± 0.056 yr⁻¹) due to the accumulation of organic matter at the soil surface indicating improved soil quality with continuous no-till management. Objective iii was addressed by conducting 29 on-farm fertilizer N response trials in major corn producing areas of Virginia with the duration of continuous no-till management ranging from 0 to 25 yrs. The ISNT values were significantly related to yield without fertilizer N (r² = 0.57; p<0.001) and relative yield (r² = 0.64; p<0.0001). We also found that the ISNT extracted a relatively consistent percentage of total soil N (16.3 ± 0.73 %) suggesting it is a poor indicator of labile N. Total soil N values did almost as well as the ISNT in predicting yield without fertilizer N (r² = 0.53; p = 0.0002), and equally well predicting relative yield (r² = 0.64; p<0.0001). Results do not suggest the ISNT is useful for measuring mineralizalbe N or improving fertilizer N recommendations in Virginia cropping systems."],"dc:description.degree":["Ph. D."],"dc:identifier.other":["etd-02102008-174038"],"dc:identifier.uri":["http://hdl.handle.net/10919/26166"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Nitrogen use efficiency","carbon trading","nutrient trading","soil organic matter"],"dc:title":["Continuous No-till Management: Implications for Soil Quality, Carbon Sequestration, and Nitrogen Conservation"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Crop and Soil Environmental Sciences"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:09Z"}