Evaluation of Ureaform Fertilizer Using Nitrogen-15-Labeled Materials in Sandy Soils1
- M. A. Brown and
- G. M. Volk2
A quantitative account of labeled ureaform and ammonium nitrate fertilizer N was made in outdoor lysimeters, greenhouse pots, and laboratory incubation vessels. A major portion of the labeled fertilizer N applied to lysimeter and greenhouse pots was recovered by crops. A greater proportion of labeled ammonium nitrate N was recovered in the plants than labeled ureaform N. However, more labeled N was found in the soil after 1 year when ureaform was the source. As a result, there were no differences in total recovery of labeled N in plants plus soil between sources. Approximately half of the N in the ureaform used in these studies was in a state of availability approaching that of ammonium nitrate. Extended availability of ureaform N over ammonium nitrate N was only apparent at the high rate of ureaform application. Approximately 15 to 20% of the ureaform material remained apparently unchanged in the soil after 1 year.
Unaccounted for N is thought to have been lost as a gas after it entered the organic N complex of the soil, since similar total recoveries were obtained for ammonium, nitrate, and ureaform N. Under anaerobic conditions significant quantities of N were lost from soils incubated with ureaform as well as from soils incubated with ammonium nitrate.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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