Coated Urea, Thiourea, Urea-Formaldehyde, Hexamine, Oxamide, Glycoluril, and Oxidized Nitrogen-Enriched Coal as Slowly Available Sources of Nitrogen for Orchardgrass1
- J. D. Beaton,
- W. A. Hubbard and
- R. C. Speer2
Yields, N uptake, and apparent recovery of applied N were determined for seven harvests of orchardgrass in the growth chamber following one surface application of several sources of N applied at rates of 56, 112, 225, and 450 mg of N per pot. Apparent recovery of N from the various sources decreased in the following order: coated (dicyclopentadiene copolymer) urea (75%) = ammonium nitrate (74%) > thiourea (690/0) > oxamide-fine (65%) = oxamide −8 +14 (65%) > urea plus thiourea (63%) > hexamine (59%) > glycoluril (49%) > urea formaldehyde (41%) > ammonium salt of oxidized nitrogenenriched coal (39%).
Yield and N uptake in the first harvest were greatest with ammoniumn itrate, urea, urea plus thiourea, and finely divided oxamide. Glycoluril and coated urea produced the highest yields and N uptake in the second and third harvests. In the later stages of cropping, yields and N uptake from the urea-formaldehyde and thiourea treatments increased and, in the final four harvests, the results obtained with these two sources were among the highest.
Thiourea depressed yield of orchardgrass when applied at the 450 mg of N rate. However, the yield of this treatment was still much greater than that of the control.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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