Tuesday, November 6, 2007
224-3

Nitrogen Release from Polymer-Coated Urea Via a Buried-Bag Technique.

Bobby Golden1, Nathan Slaton1, Russell Delong1, and Richard Norman2. (1) University of Arkansas, 1366 W Altheimer Drive, Fayetteville, AR 72704, (2) Ptsc 115, University of Arkansas, University of Arkansas, Department of Agronomy, Fayetteville, AR 72701

Nitrogen fertilization in delayed-flood rice (Oryza sativa L.) production relies heavily on aerial application of urea.  Urea application with ground equipment before seeding may reduce N-application costs.  Our objective was to evaluate the N-release patterns of polymer-coated urea (PCU) fertilizers. Two PCU fertilizers (ESN and ‘Duration-V’, Agrium Inc.) were evaluated in field experiments established in a Calhoun and Dewitt silt loam and in a laboratory incubation (Calhoun soil, 20C, and 25% gravimetric moisture).  Prills of PCU (6) were weighed, placed in mesh bags, and buried immediately following rice seeding. Each bag contained 38-44 mg N. Bags were unearthed every 5 (lab) or 10 (field) d after burial beginning 10 d after and ending 40 d after burial. The recovered bags were placed in sealed plastic bags, transported on ice, and refrigerated until analysis. Prills were removed from each bag, counted, and the total-N remaining was determining by combustion. At 10 d after burial, 78 to 100% of the initial N remained compared to 3 to 49% remaining by 40 d. The proportion of fertilizer-N remaining declined linearly or nonlinearly across time depending on PCU and environment (field or lab). Nitrogen release from both fertilizers incubated in the lab was slower than under field conditions and N release from ESN was faster than Duration-V. Nitrogen release from ESN was nonlinear. For ESN, the linear and nonlinear coefficients between the Dewitt (1.533 -0.0901x +0.00134x2) and Calhoun (1.707 –0.0948x +0.00137x2) field-soil incubations were similar, but significantly greater than the coefficients from the lab incubation (1.398 –0.0495x +0.00047x2).  Nitrogen release from Duration-V was similar and linear in Dewitt (1.349 –0.0402x) and Calhoun (1.327 –0.0412x) field-soil incubations, but nonlinear in the lab incubation (0.825 +0.0166x -0.00062x2). Differences in soil temperature, moisture, or both may explain why N release was slower in the lab incubation.

Back to Symposium--Aspects of Nutrient Use Related to Biofuels Production (included Graduate Student Competition)
Back to S08 Nutrient Management & Soil & Plant Analysis

Back to The ASA-CSSA-SSSA International Annual Meetings (November 4-8, 2007)