{"id":{"repo_id":"ag-u-iceland","oai_identifier":"oai:skemman.is:1946/53363"},"canonical_url":"https://search.dev.ndltd.org/etd/ag-u-iceland/oai:skemman.is:1946/53363","repository":{"repo_id":"ag-u-iceland","name":"Agricultural University of Iceland","base_url":"https://skemman.is/oai/request"},"display":{"title":"The Effect of Split Nitrogen Fertilization on Yield, Quality, and Nitrogen Use Efficiency of Spring Barley Grown on Two Different Soil Types in Iceland","abstract":"Split nitrogen (N) fertilization is a strategy aimed at maximizing nitrogen use efficiency (NUE) by applying N at specific growth stages when plant utilization is greatest, thereby minimizing environmental impacts from runoff and greenhouse gas emissions. Icelandic studies on split fertilization in cereal cultivation are scarce, and the practice is uncommon amongst cereal farmers in Iceland. Consequently, little is known about the potential benefits of this strategy under Icelandic conditions. Trials were conducted at two locations in Iceland, using two different soil types and two spring barley varieties, Smyrill (six-row) and Kría (two-row), to study the effects of different N split applications on growth, grain yield, grain protein content (GPC), and NUE. Treatments included single fertilization at sowing, early booting, and/or late anthesis with different N rates for each application. Splitting N did not increase grain yield compared to a single application at sowing, but high N doses at sowing tended to increase grain yield. The effect of soil type was greater on yield and grain size. An association was found between grain size and GPC, with smaller grains giving higher GPC. The six-row variety had significantly higher GPC than the two-row variety at both locations. Single application had the highest NUE at both locations and both varieties, while 67/16.5/16.5% split resulted in the highest total N uptake and lowest unaccounted N. In a cold and wet growing season, split fertilization at early booting and/or late anthesis does not appear to have a positive effect on barley’s yield, quality, and NUE in barley cultivation in Iceland","abstract_html":"Split nitrogen (N) fertilization is a strategy aimed at maximizing nitrogen use efficiency (NUE) by applying N at specific growth stages when plant utilization is greatest, thereby minimizing environmental impacts from runoff and greenhouse gas emissions. Icelandic studies on split fertilization in cereal cultivation are scarce, and the practice is uncommon amongst cereal farmers in Iceland. Consequently, little is known about the potential benefits of this strategy under Icelandic conditions. Trials were conducted at two locations in Iceland, using two different soil types and two spring barley varieties, Smyrill (six-row) and Kría (two-row), to study the effects of different N split applications on growth, grain yield, grain protein content (GPC), and NUE. Treatments included single fertilization at sowing, early booting, and/or late anthesis with different N rates for each application. Splitting N did not increase grain yield compared to a single application at sowing, but high N doses at sowing tended to increase grain yield. The effect of soil type was greater on yield and grain size. An association was found between grain size and GPC, with smaller grains giving higher GPC. The six-row variety had significantly higher GPC than the two-row variety at both locations. Single application had the highest NUE at both locations and both varieties, while 67/16.5/16.5% split resulted in the highest total N uptake and lowest unaccounted N. In a cold and wet growing season, split fertilization at early booting and/or late anthesis does not appear to have a positive effect on barley’s yield, quality, and NUE in barley cultivation in Iceland","abstract_has_math":false,"creators":["Sunna Skeggjadóttir 1999-"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Landbúnaðarháskóli Íslands"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-05-26T12:28:49Z","date_published":"2026-05-26T12:28:49Z","updated_at":"2026-07-27T18:40:16Z","subjects":["Bygg","Skipt köfnunarefnis áburðargjöf","Nitur","Vaxtarstig","Uppskeruþættir","Prótín","Niturnýtni"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1946/53363","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Landbúnaðarháskóli Íslands"]},{"key":"dc:creator","label":"Author","values":["Sunna Skeggjadóttir 1999-"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-05-26T12:28:45Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-05-26T12:28:45Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-05-26T12:28:49Z"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Bygg","Skipt köfnunarefnis áburðargjöf","Nitur","Vaxtarstig","Uppskeruþættir","Prótín","Niturnýtni"]}]},{"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/1946/53363"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Split nitrogen (N) fertilization is a strategy aimed at maximizing nitrogen use efficiency (NUE) by applying N at specific growth stages when plant utilization is greatest, thereby minimizing environmental impacts from runoff and greenhouse gas emissions. Icelandic studies on split fertilization in cereal cultivation are scarce, and the practice is uncommon amongst cereal farmers in Iceland. Consequently, little is known about the potential benefits of this strategy under Icelandic conditions. Trials were conducted at two locations in Iceland, using two different soil types and two spring barley varieties, Smyrill (six-row) and Kría (two-row), to study the effects of different N split applications on growth, grain yield, grain protein content (GPC), and NUE. Treatments included single fertilization at sowing, early booting, and/or late anthesis with different N rates for each application. Splitting N did not increase grain yield compared to a single application at sowing, but high N doses at sowing tended to increase grain yield. The effect of soil type was greater on yield and grain size. An association was found between grain size and GPC, with smaller grains giving higher GPC. The six-row variety had significantly higher GPC than the two-row variety at both locations. Single application had the highest NUE at both locations and both varieties, while 67/16.5/16.5% split resulted in the highest total N uptake and lowest unaccounted N. In a cold and wet growing season, split fertilization at early booting and/or late anthesis does not appear to have a positive effect on barley’s yield, quality, and NUE in barley cultivation in Iceland","Skipting köfnunarefnis (N) er aðferð sem hefur það að markmiði að hámarka niturnýtni (NUE) með því að tímasetja áburðargjöfina út frá ákveðnum vaxtarstigum þar sem nýting plantna er sem mest og þar með lágmarka umhverfisáhrif á borð við útskolun og losun gróðurhúsalofttegunda. Íslenskar rannsóknir á skiptri áburðargjöf í kornrækt eru fáar og aðferðin óalgeng meðal kornbænda á Íslandi. Þar að leiðandi er lítið vitað um mögulegan ávinning þessarar aðferðar við íslenskar aðstæður. Lagðar voru út tilraunir á tveimur jarðvegsgerðum með tveimur byggyrkjum, Smyril (sexraða) og Kríu (tvíraða), til þess að kanna áhrif mismunandi N skiptingar á vöxt, uppskeru próteininnihald korns (GPC) og NUE. Áburðarliðirnir innihéldu eina áburðargjöf við sáningu og skiptingu snemma á fánablaðslíðurfyllingastigi og/eða við lok blómgunar með mismunandi N magni við hverja áburðargjöf. Skipting N áburðar jók ekki uppskeru samanborið við eina áburðargjöf að vori (100/0/0%), en hár N skammtur við sáningu hafði tilhneigingu til þess að auka uppskeru. Áhrif jarðvegsgerðar voru meiri en áburðarliða á uppskeru og kornastærð. Samband fannst á milli kornastærðar og GPC, en smærri fræ sýndu hærra GPC. Sexraða yrkið var með marktækt meira GPC en tvíraða yrkið á báðum stöðum, en skiptingin 67/16.5/16.5% skilaði hærri heildar N upptöku og minna N tapi. Á vaxtartímabili sem einkennist af kulda og úrkomu virðist skipt N áburðargjöf snemma á fánablaðslíðurfyllingastigi og/eða í lok blómgunar ekki skila ávinningi þegar kemur að uppskeru, gæði og NUE í byggrækt á Íslandi."]},{"key":"dc:title","label":"Title","values":["The Effect of Split Nitrogen Fertilization on Yield, Quality, and Nitrogen Use Efficiency of Spring Barley Grown on Two Different Soil Types in Iceland","Áhrif skiptrar áburðargjafar á uppskeru, gæði og niturnýtni vor byggs ræktað á tveimur ólíkum jarðvegsgerðum á Íslandi"]}]}],"canonical_facts":{"dc:contributor":["Landbúnaðarháskóli Íslands"],"dc:creator":["Sunna Skeggjadóttir 1999-"],"dc:date.accessioned":["2026-05-26T12:28:45Z"],"dc:date.available":["2026-05-26T12:28:45Z"],"dc:date.issued":["2026-05-26T12:28:49Z"],"dc:description.abstract":["Split nitrogen (N) fertilization is a strategy aimed at maximizing nitrogen use efficiency (NUE) by applying N at specific growth stages when plant utilization is greatest, thereby minimizing environmental impacts from runoff and greenhouse gas emissions. Icelandic studies on split fertilization in cereal cultivation are scarce, and the practice is uncommon amongst cereal farmers in Iceland. Consequently, little is known about the potential benefits of this strategy under Icelandic conditions. Trials were conducted at two locations in Iceland, using two different soil types and two spring barley varieties, Smyrill (six-row) and Kría (two-row), to study the effects of different N split applications on growth, grain yield, grain protein content (GPC), and NUE. Treatments included single fertilization at sowing, early booting, and/or late anthesis with different N rates for each application. Splitting N did not increase grain yield compared to a single application at sowing, but high N doses at sowing tended to increase grain yield. The effect of soil type was greater on yield and grain size. An association was found between grain size and GPC, with smaller grains giving higher GPC. The six-row variety had significantly higher GPC than the two-row variety at both locations. Single application had the highest NUE at both locations and both varieties, while 67/16.5/16.5% split resulted in the highest total N uptake and lowest unaccounted N. In a cold and wet growing season, split fertilization at early booting and/or late anthesis does not appear to have a positive effect on barley’s yield, quality, and NUE in barley cultivation in Iceland","Skipting köfnunarefnis (N) er aðferð sem hefur það að markmiði að hámarka niturnýtni (NUE) með því að tímasetja áburðargjöfina út frá ákveðnum vaxtarstigum þar sem nýting plantna er sem mest og þar með lágmarka umhverfisáhrif á borð við útskolun og losun gróðurhúsalofttegunda. Íslenskar rannsóknir á skiptri áburðargjöf í kornrækt eru fáar og aðferðin óalgeng meðal kornbænda á Íslandi. Þar að leiðandi er lítið vitað um mögulegan ávinning þessarar aðferðar við íslenskar aðstæður. Lagðar voru út tilraunir á tveimur jarðvegsgerðum með tveimur byggyrkjum, Smyril (sexraða) og Kríu (tvíraða), til þess að kanna áhrif mismunandi N skiptingar á vöxt, uppskeru próteininnihald korns (GPC) og NUE. Áburðarliðirnir innihéldu eina áburðargjöf við sáningu og skiptingu snemma á fánablaðslíðurfyllingastigi og/eða við lok blómgunar með mismunandi N magni við hverja áburðargjöf. Skipting N áburðar jók ekki uppskeru samanborið við eina áburðargjöf að vori (100/0/0%), en hár N skammtur við sáningu hafði tilhneigingu til þess að auka uppskeru. Áhrif jarðvegsgerðar voru meiri en áburðarliða á uppskeru og kornastærð. Samband fannst á milli kornastærðar og GPC, en smærri fræ sýndu hærra GPC. Sexraða yrkið var með marktækt meira GPC en tvíraða yrkið á báðum stöðum, en skiptingin 67/16.5/16.5% skilaði hærri heildar N upptöku og minna N tapi. Á vaxtartímabili sem einkennist af kulda og úrkomu virðist skipt N áburðargjöf snemma á fánablaðslíðurfyllingastigi og/eða í lok blómgunar ekki skila ávinningi þegar kemur að uppskeru, gæði og NUE í byggrækt á Íslandi."],"dc:identifier.uri":["https://hdl.handle.net/1946/53363"],"dc:language.iso":["en"],"dc:subject":["Bygg","Skipt köfnunarefnis áburðargjöf","Nitur","Vaxtarstig","Uppskeruþættir","Prótín","Niturnýtni"],"dc:title":["The Effect of Split Nitrogen Fertilization on Yield, Quality, and Nitrogen Use Efficiency of Spring Barley Grown on Two Different Soil Types in Iceland","Áhrif skiptrar áburðargjafar á uppskeru, gæði og niturnýtni vor byggs ræktað á tveimur ólíkum jarðvegsgerðum á Íslandi"],"dc:type":["Thesis"]},"updated_at":"2026-07-27T18:40:16Z"}