{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/35194"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/35194","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Nitrogen modeling of potato fields in the Bolivian Andes using GLEAMS","abstract":"An increase in population in rural agricultural communities and higher demand for food throughout Bolivia create the need for increased agricultural production. The objective of this study was to assess the suitability of the GLEAMS model as a tool for evaluating fertilization and cropping system practices for potatoes in the Andes of central Bolivia, and make recommendations for the continued development of the model as an analysis tool to improve sustainable crop production. Model suitability was evaluated through assessment of model representation of observed potato farms and behavior of simulated soil nitrogen (N) and N transformation trends; validation with field data taken from six agricultural sites in central Bolivia for runoff volume, soil total Kjeldahl N concentration, crop production, and crop N uptake; and sensitivity analysis. Validation of model output with observed values was completed both graphically and by determining the root mean square error standard deviation ratio (RSR) and the percent bias (PBIAS). RSR and PBIAS values for runoff volume were 4.0 and 65%, 4.5 and 4%, and 2.7 and 55% for three respective experimental plot repetitions using a calibrated SCS curve number of 90. The RSR and PBIAS, respectively, for soil total Kjeldahl N concentration were 3.0 and -2.2%. The RSR and PBIAS, respectively, for crop dry matter production were 7 and 21%. The RSR and PBIAS, respectively, for crop N uptake were 10 and 21%. The mineralization processes in GLEAMS must be improved before model application to central Bolivia, where agricultural production is highly dependent on mineralization of organic N from soil and applied animal manure. Recommendations for model improvement and development include modification to the process that determines mineralization from the soil potentially mineralizable N pool; validation of the percolation volume and nitrate leaching losses; and improved model representation of banded manure application.","abstract_html":"An increase in population in rural agricultural communities and higher demand for food throughout Bolivia create the need for increased agricultural production. The objective of this study was to assess the suitability of the GLEAMS model as a tool for evaluating fertilization and cropping system practices for potatoes in the Andes of central Bolivia, and make recommendations for the continued development of the model as an analysis tool to improve sustainable crop production. Model suitability was evaluated through assessment of model representation of observed potato farms and behavior of simulated soil nitrogen (N) and N transformation trends; validation with field data taken from six agricultural sites in central Bolivia for runoff volume, soil total Kjeldahl N concentration, crop production, and crop N uptake; and sensitivity analysis. Validation of model output with observed values was completed both graphically and by determining the root mean square error standard deviation ratio (RSR) and the percent bias (PBIAS). RSR and PBIAS values for runoff volume were 4.0 and 65%, 4.5 and 4%, and 2.7 and 55% for three respective experimental plot repetitions using a calibrated SCS curve number of 90. The RSR and PBIAS, respectively, for soil total Kjeldahl N concentration were 3.0 and -2.2%. The RSR and PBIAS, respectively, for crop dry matter production were 7 and 21%. The RSR and PBIAS, respectively, for crop N uptake were 10 and 21%. The mineralization processes in GLEAMS must be improved before model application to central Bolivia, where agricultural production is highly dependent on mineralization of organic N from soil and applied animal manure. Recommendations for model improvement and development include modification to the process that determines mineralization from the soil potentially mineralizable N pool; validation of the percolation volume and nitrate leaching losses; and improved model representation of banded manure application.","abstract_has_math":false,"creators":["Walker, Sarah Madeline"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Biological Systems Engineering","degree_department":"Biological Systems Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Heatwole, Conrad D."],"committee_members":["Wolfe, Mary Leigh","Alley, Marcus M."],"year":2009,"date_issued":"2009-09-11","date_published":"2009-09-11","updated_at":"2026-07-22T22:18:50Z","subjects":["Bolivia","Andes","manure","GLEAMS model","potato","Nitrogen"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["4516"],"render_values":[{"text":"4516","href":null,"code":true}]},{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-09252009-161328"],"render_values":[{"text":"etd-09252009-161328","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/35194","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Heatwole, Conrad D."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Wolfe, Mary Leigh","Alley, Marcus M."]},{"key":"dc:contributor.department","label":"Department","values":["Biological Systems Engineering"]},{"key":"dc:creator","label":"Author","values":["Walker, Sarah Madeline"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:45:59Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:45:59Z","2009-10-01"]},{"key":"dc:date.issued","label":"Date","values":["2009-09-11"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biological Systems Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Bolivia","Andes","manure","GLEAMS model","potato","Nitrogen"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["4516"]},{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-09252009-161328"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/35194"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["An increase in population in rural agricultural communities and higher demand for food throughout Bolivia create the need for increased agricultural production. The objective of this study was to assess the suitability of the GLEAMS model as a tool for evaluating fertilization and cropping system practices for potatoes in the Andes of central Bolivia, and make recommendations for the continued development of the model as an analysis tool to improve sustainable crop production. Model suitability was evaluated through assessment of model representation of observed potato farms and behavior of simulated soil nitrogen (N) and N transformation trends; validation with field data taken from six agricultural sites in central Bolivia for runoff volume, soil total Kjeldahl N concentration, crop production, and crop N uptake; and sensitivity analysis. Validation of model output with observed values was completed both graphically and by determining the root mean square error standard deviation ratio (RSR) and the percent bias (PBIAS). RSR and PBIAS values for runoff volume were 4.0 and 65%, 4.5 and 4%, and 2.7 and 55% for three respective experimental plot repetitions using a calibrated SCS curve number of 90. The RSR and PBIAS, respectively, for soil total Kjeldahl N concentration were 3.0 and -2.2%. The RSR and PBIAS, respectively, for crop dry matter production were 7 and 21%. The RSR and PBIAS, respectively, for crop N uptake were 10 and 21%. The mineralization processes in GLEAMS must be improved before model application to central Bolivia, where agricultural production is highly dependent on mineralization of organic N from soil and applied animal manure. Recommendations for model improvement and development include modification to the process that determines mineralization from the soil potentially mineralizable N pool; validation of the percolation volume and nitrate leaching losses; and improved model representation of banded manure application."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Nitrogen modeling of potato fields in the Bolivian Andes using GLEAMS"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Heatwole, Conrad D."],"dc:contributor.committeemember":["Wolfe, Mary Leigh","Alley, Marcus M."],"dc:contributor.department":["Biological Systems Engineering"],"dc:creator":["Walker, Sarah Madeline"],"dc:date.accessioned":["2014-03-14T20:45:59Z"],"dc:date.available":["2014-03-14T20:45:59Z","2009-10-01"],"dc:date.issued":["2009-09-11"],"dc:description.abstract":["An increase in population in rural agricultural communities and higher demand for food throughout Bolivia create the need for increased agricultural production. The objective of this study was to assess the suitability of the GLEAMS model as a tool for evaluating fertilization and cropping system practices for potatoes in the Andes of central Bolivia, and make recommendations for the continued development of the model as an analysis tool to improve sustainable crop production. Model suitability was evaluated through assessment of model representation of observed potato farms and behavior of simulated soil nitrogen (N) and N transformation trends; validation with field data taken from six agricultural sites in central Bolivia for runoff volume, soil total Kjeldahl N concentration, crop production, and crop N uptake; and sensitivity analysis. Validation of model output with observed values was completed both graphically and by determining the root mean square error standard deviation ratio (RSR) and the percent bias (PBIAS). RSR and PBIAS values for runoff volume were 4.0 and 65%, 4.5 and 4%, and 2.7 and 55% for three respective experimental plot repetitions using a calibrated SCS curve number of 90. The RSR and PBIAS, respectively, for soil total Kjeldahl N concentration were 3.0 and -2.2%. The RSR and PBIAS, respectively, for crop dry matter production were 7 and 21%. The RSR and PBIAS, respectively, for crop N uptake were 10 and 21%. The mineralization processes in GLEAMS must be improved before model application to central Bolivia, where agricultural production is highly dependent on mineralization of organic N from soil and applied animal manure. Recommendations for model improvement and development include modification to the process that determines mineralization from the soil potentially mineralizable N pool; validation of the percolation volume and nitrate leaching losses; and improved model representation of banded manure application."],"dc:description.degree":["Master of Science"],"dc:identifier":["4516"],"dc:identifier.other":["etd-09252009-161328"],"dc:identifier.uri":["http://hdl.handle.net/10919/35194"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Bolivia","Andes","manure","GLEAMS model","potato","Nitrogen"],"dc:title":["Nitrogen modeling of potato fields in the Bolivian Andes using GLEAMS"],"dc:type":["Thesis"],"thesis:degree_discipline":["Biological Systems Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:50Z"}