Data/hora: 16/06/2024 09:30:38

Biblioteca(s): | Embrapa Solos.
Data corrente: | 22/11/2002
Data da última atualização: | 22/11/2002
Autoria: | TEDESCO, M. J.
Título: | I. Analysis of 15N: evaluation of sample preparation and analysis methology with an optical 15N analyzer. II. The fate of urea fertilizer in some soils of Rio Grande do Sul, Brazil.
Ano de publicação: | 1972
Fonte/Imprenta: | s.l.: University of Wisconsin, 1972.
Páginas: | 127p.
Idioma: | Inglês
Notas: | Ph.D. Thesis.
Conteúdo: | A comercially available optical 15N analyzer and sample preparation unit were evaluated with respect to ease of use, sample size, reproducibility and accuracy. The sample prep unit, which utilized a Dumas combustion approach to produce N2, was modified extensively and the hypobromite oxidation method for N2 production was adopted. Instrumentation problems and source of error include monlinear gain settings, baseline determination, overlapping peak heights and monlinear gain settings, baseline determination, overlapping peak heights and monlinearity of the standard curve. Problems in the sample method adopted were limited to memory in the discharge tube. This was reduced by prolonged heating of the tubes at 700 oC. Minimum sample size is about 10 ug of N. In the normal abundance to 5 atom % 15N range, the methid gave 0.01 confidence interval values of +- 0.031 atom % 15N. The analyzer was simple, rapid and free of downtime relative to most mass spectrometers. Transformation of pelleted 2.92 atmo % 15N urea fertilizer when applied 2 cm from the surface at the rate of 200 ppm in four acid Brazilian soils was studied. Each experimental unit was enclosed in a plexiglass chamber with controlled aeration, allowing determination of the NH3 and NO2 volatilized. The effects of cropping to ryegrass and liming were evaluated. Fertilizer N volatization losse as NH3 and NO2 could account at the most for only 2% of the N added. While no relationship was observed for NH3 volatilized, NO2 collected was greater for the .............
Categoria do assunto: | --
Registro original: | Embrapa Solos (CNPS)
Exemplares: | CNPS - (4640-1) - ADD - TS - -- - 72015 - TED/72 - 1997.02449 - DIS