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Title: Nitrogen source and rate effects on furrow irrigated corn yields and NUE

Author
item Halvorson, Ardell
item BARTOLO, MICHAEL - Colorado State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2013
Publication Date: 4/23/2014
Publication URL: http://doi: 10.2134/agronj2013.0001
Citation: Halvorson, A.D., Bartolo, M. 2014. Nitrogen source and rate effects on furrow irrigated corn yields and NUE. Agronomy Journal. Vol. 106:681-693..

Interpretive Summary: Nitrogen (N) rate studies were conducted under furrow irrigated corn production to compare polymer-coated urea (PCU) and stabilized urea (SU) effects on corn yields, plant N uptake and N use efficiency (NUE) to those with granular urea. PCU had a yield advantage over urea two of three years. PCU’s yield advantage occurred during two continuous corn years, resulting in greater economic returns with PCU (4 to 14%) at N rates from 168 to 280 kg N ha-1. The SU fertilizer had no yield or economic advantage over urea. Grain yields and N uptake increased with increasing N rate for all N sources. A linear-plateau model comparing grain yields from all N sources as a function of N rate showed yields were maximized at 14.3 Mg ha-1 at a N rate of 254 kg N ha-1 or available N level (soil N plus fertilizer N) of 295 kg N ha-1. Nitrogen recovery efficiency (RE) tended not to vary with N rate with no differences between SU and urea, but greater RE (19%) with PCU than urea under continuous corn. Fertilizer N use efficiency did not vary with N rate, but was greater for PCU (36%) than for urea (32%) under continuous corn. In contrast to SU, PCU provided grain yield and potential economic advantages over urea under continuous corn production at N rates below those needed with urea for maximum grain yield.

Technical Abstract: Nitrogen (N) rate studies were conducted under furrow irrigated corn (Zea mays L.) production on a silty clay soil to compare polymer-coated urea (PCU) and stabilized urea (SU; contains urease and nitrification inhibitors) effects on corn yields, plant N uptake and N use efficiency (NUE) to granular urea. PCU had a yield advantage over urea two of three years at N rates below maximum yield. PCU’s yield advantage occurred during two continuous corn years, resulting in greater economic returns with PCU (4 to 14%) at N rates from 168 to 280 kg N ha-1. The SU fertilizer had no yield or economic advantage over urea. Grain and stover yields and N uptake increased with increasing N rate for all N sources. Expressing grain yields from all N sources as a linear-plateau function of N rate showed that yields were maximized at 14.3 Mg ha-1 at a N rate of 254 kg N ha-1 or available N level (soil N plus fertilizer N) of 295 kg N ha-1. Nitrogen recovery efficiency (RE) tended not to vary with N rate with no differences between SU and urea, but greater RE (19%) with PCU than urea under continuous corn. Fertilizer N use efficiency (FNUE) did not vary with N rate, but was greater for PCU (36%) than for urea (32%) under continuous corn. In contrast to SU, PCU provided grain yield and potential economic advantages over urea under continuous corn production at N rates below those needed with urea for maximum grain yield.