The two methods for determining N-fertilizer recommendations for rice (Oryza sativa L.) in Arkansas are the standard N recommendation (SR) based on soil texture, previous crop, and rice cultivar, and the Nitrogen-Soil Test for Rice (N-STaR) which quantifies the potentially mineralizable-N of the soil and provides a site-specific N recommendation. The N-STaR program has recently been developed, and the validation of N-STaR for clay soils is an important step in ensuring that N-STaR predicts correct N-fertilizer rates for rice under a delayed-flood production system. Small-plot trials located across Arkansas compared the N-STaR 95 and 100% relative grain yield (RGY) N rates applied as a single preflood (SPF) and a 2-way split (2-WS) application to the SR. The N-STaR N-fertilizer rate recommendations were equal to or less than the SR at all locations with differences ranging from -224 to 0 kg N ha-1. At all 13 sites, rice receiving the N-STaR 100% RGY N-fertilizer treatments yielded equal to or greater than the SR. Similar results were seen for the N-STaR 95% RGY fertilizer-N treatments, although rice receiving the 95% RGY SPF fertilizer-N rate yielded lower than the SR at three locations. The second objective was to examine potential sampling tools for their accuracy in collecting N-STaR soil samples while having the greatest ease-of-use. Alkaline hydrolyzable-N (AH-N) from soil samples collected by the N-STaR bucket and drill (BD), Kleen Hole Spade dry (KHS-D), Kleen Hole Spade lubricated with water (KHS-W), and Kleen Hole Spade lubricated with WD-40 (KHS-40) were compared against the dutch auger (DA) control. The alternative sampling methods were not statistically different in AH-N concentration from the DA, although all alternative methods had a tendency to overestimate AH-N compared to the DA and a correction value should be considered. The KHS-D showed the greatest utility in sampling clay soils and would be the best alternative method for encouraging the use of N-STaR in rice production on clay soils. In conclusion, this research validates the N-STaR N rate recommendations for rice on clay soils in Arkansas and highlights alternative sampling methods that may be employed in N-STaR soil sampling.
","abstract_html":"<p>The two methods for determining N-fertilizer recommendations for rice (Oryza sativa L.) in Arkansas are the standard N recommendation (SR) based on soil texture, previous crop, and rice cultivar, and the Nitrogen-Soil Test for Rice (N-STaR) which quantifies the potentially mineralizable-N of the soil and provides a site-specific N recommendation. The N-STaR program has recently been developed, and the validation of N-STaR for clay soils is an important step in ensuring that N-STaR predicts correct N-fertilizer rates for rice under a delayed-flood production system. Small-plot trials located across Arkansas compared the N-STaR 95 and 100% relative grain yield (RGY) N rates applied as a single preflood (SPF) and a 2-way split (2-WS) application to the SR. The N-STaR N-fertilizer rate recommendations were equal to or less than the SR at all locations with differences ranging from -224 to 0 kg N ha-1. At all 13 sites, rice receiving the N-STaR 100% RGY N-fertilizer treatments yielded equal to or greater than the SR. Similar results were seen for the N-STaR 95% RGY fertilizer-N treatments, although rice receiving the 95% RGY SPF fertilizer-N rate yielded lower than the SR at three locations. The second objective was to examine potential sampling tools for their accuracy in collecting N-STaR soil samples while having the greatest ease-of-use. Alkaline hydrolyzable-N (AH-N) from soil samples collected by the N-STaR bucket and drill (BD), Kleen Hole Spade dry (KHS-D), Kleen Hole Spade lubricated with water (KHS-W), and Kleen Hole Spade lubricated with WD-40 (KHS-40) were compared against the dutch auger (DA) control. The alternative sampling methods were not statistically different in AH-N concentration from the DA, although all alternative methods had a tendency to overestimate AH-N compared to the DA and a correction value should be considered. The KHS-D showed the greatest utility in sampling clay soils and would be the best alternative method for encouraging the use of N-STaR in rice production on clay soils. In conclusion, this research validates the N-STaR N rate recommendations for rice on clay soils in Arkansas and highlights alternative sampling methods that may be employed in N-STaR soil sampling.</p>","abstract_has_math":false,"creators":["Davidson, Jarom Thane"],"institution":null,"degree_name":"Master of Science in Crop, Soil & Environmental Sciences (MS)","degree_level":"Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Slaton, Nathan A.","Hardke, Jarrod T."],"advisors":["Roberts, Trenton L."],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-08-01T07:00:00Z","date_published":"2016-08-01T07:00:00Z","updated_at":"2026-07-24T00:59:40Z","subjects":["Biological sciences","Clay soil","N-star","Soil sampling","Sedimentology","Soil Science"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.uark.edu/etd/1622","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Slaton, Nathan A.","Hardke, Jarrod T."]},{"key":"dc:contributor.advisor","label":"Advisor","values":["Roberts, Trenton L."]},{"key":"dc:creator","label":"Author","values":["Davidson, Jarom Thane"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-09-29T07:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science in Crop, Soil & Environmental Sciences (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biological sciences","Clay soil","N-star","Soil sampling","Sedimentology","Soil Science"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarworks.uark.edu/etd/1622"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The two methods for determining N-fertilizer recommendations for rice (Oryza sativa L.) in Arkansas are the standard N recommendation (SR) based on soil texture, previous crop, and rice cultivar, and the Nitrogen-Soil Test for Rice (N-STaR) which quantifies the potentially mineralizable-N of the soil and provides a site-specific N recommendation. The N-STaR program has recently been developed, and the validation of N-STaR for clay soils is an important step in ensuring that N-STaR predicts correct N-fertilizer rates for rice under a delayed-flood production system. Small-plot trials located across Arkansas compared the N-STaR 95 and 100% relative grain yield (RGY) N rates applied as a single preflood (SPF) and a 2-way split (2-WS) application to the SR. The N-STaR N-fertilizer rate recommendations were equal to or less than the SR at all locations with differences ranging from -224 to 0 kg N ha-1. At all 13 sites, rice receiving the N-STaR 100% RGY N-fertilizer treatments yielded equal to or greater than the SR. Similar results were seen for the N-STaR 95% RGY fertilizer-N treatments, although rice receiving the 95% RGY SPF fertilizer-N rate yielded lower than the SR at three locations. The second objective was to examine potential sampling tools for their accuracy in collecting N-STaR soil samples while having the greatest ease-of-use. Alkaline hydrolyzable-N (AH-N) from soil samples collected by the N-STaR bucket and drill (BD), Kleen Hole Spade dry (KHS-D), Kleen Hole Spade lubricated with water (KHS-W), and Kleen Hole Spade lubricated with WD-40 (KHS-40) were compared against the dutch auger (DA) control. The alternative sampling methods were not statistically different in AH-N concentration from the DA, although all alternative methods had a tendency to overestimate AH-N compared to the DA and a correction value should be considered. The KHS-D showed the greatest utility in sampling clay soils and would be the best alternative method for encouraging the use of N-STaR in rice production on clay soils. In conclusion, this research validates the N-STaR N rate recommendations for rice on clay soils in Arkansas and highlights alternative sampling methods that may be employed in N-STaR soil sampling.
"]},{"key":"dc:title","label":"Title","values":["Validation of N-STaR Nitrogen Rate Recommendations and Evaluation of N-STaR Soil Sampling Procedures for Clay Soils in Arkansas"]}]}],"canonical_facts":{"dc:contributor":["Slaton, Nathan A.","Hardke, Jarrod T."],"dc:contributor.advisor":["Roberts, Trenton L."],"dc:creator":["Davidson, Jarom Thane"],"dc:date":["2016"],"dc:date.available":["2017-09-29T07:00:00Z"],"dc:description.abstract":["The two methods for determining N-fertilizer recommendations for rice (Oryza sativa L.) in Arkansas are the standard N recommendation (SR) based on soil texture, previous crop, and rice cultivar, and the Nitrogen-Soil Test for Rice (N-STaR) which quantifies the potentially mineralizable-N of the soil and provides a site-specific N recommendation. The N-STaR program has recently been developed, and the validation of N-STaR for clay soils is an important step in ensuring that N-STaR predicts correct N-fertilizer rates for rice under a delayed-flood production system. Small-plot trials located across Arkansas compared the N-STaR 95 and 100% relative grain yield (RGY) N rates applied as a single preflood (SPF) and a 2-way split (2-WS) application to the SR. The N-STaR N-fertilizer rate recommendations were equal to or less than the SR at all locations with differences ranging from -224 to 0 kg N ha-1. At all 13 sites, rice receiving the N-STaR 100% RGY N-fertilizer treatments yielded equal to or greater than the SR. Similar results were seen for the N-STaR 95% RGY fertilizer-N treatments, although rice receiving the 95% RGY SPF fertilizer-N rate yielded lower than the SR at three locations. The second objective was to examine potential sampling tools for their accuracy in collecting N-STaR soil samples while having the greatest ease-of-use. Alkaline hydrolyzable-N (AH-N) from soil samples collected by the N-STaR bucket and drill (BD), Kleen Hole Spade dry (KHS-D), Kleen Hole Spade lubricated with water (KHS-W), and Kleen Hole Spade lubricated with WD-40 (KHS-40) were compared against the dutch auger (DA) control. The alternative sampling methods were not statistically different in AH-N concentration from the DA, although all alternative methods had a tendency to overestimate AH-N compared to the DA and a correction value should be considered. The KHS-D showed the greatest utility in sampling clay soils and would be the best alternative method for encouraging the use of N-STaR in rice production on clay soils. In conclusion, this research validates the N-STaR N rate recommendations for rice on clay soils in Arkansas and highlights alternative sampling methods that may be employed in N-STaR soil sampling.
"],"dc:identifier":["https://scholarworks.uark.edu/etd/1622"],"dc:subject":["Biological sciences","Clay soil","N-star","Soil sampling","Sedimentology","Soil Science"],"dc:title":["Validation of N-STaR Nitrogen Rate Recommendations and Evaluation of N-STaR Soil Sampling Procedures for Clay Soils in Arkansas"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science in Crop, Soil & Environmental Sciences (MS)"]},"updated_at":"2026-07-24T00:59:40Z"}