Data/hora: 02/06/2024 03:37:18

Provedor de dados: | 63
País: | Brazil
Título: | Comparison of carbon and nitrogen determination methods for samples of a Paleudult subjected to no-till cropping systems
Autores: | Dieckow,Jeferson; Mielniczuk,João; Knicker,Heike; Bayer,Cimélio; Dick,Deborah Pinheiro; Kögel-Knabner,Ingrid.
Data: | 2007-10-01
Ano: | 2007
Palavras-chave: | Walkley-Black; Kjeldahl; Wet combustion; Dry combustion.
Resumo: | Organic carbon (C) concentration evaluated by the Walkley-Black method, and total nitrogen(N)concentration determined by Kjeldahl method, were compared with corresponding results of C and N concentrations obtained through the dry combustion method (Elementar Vario EL analyzer), using samples of ten soil layers down to the depth of 107.5 cm of a kaolinitic Typic Paleudult (220-418 g clay kg-1 along the profile) subjected to no-till cropping systems [fallow bare soil, pigeon pea (Cajanus cajan L. Millsp.) plus maize, and lablab (Lablab purpureum L. Sweet) plus maize]. A close correlation (R² &gt; 0.96) was observed between the C results of the Walkley-Black and dry combustion methods, but a correction was suggested to be applied to C results of Walkley-Black (C = 1.05C W.Black + 0.47). A close correlation (R² &gt; 0.96) was also found between results of Kjeldahl-N and dry combustion-N, but no correction was necessary to be applied. The relationships between results of Walkley-Black and dry combustion and between results of Kjeldahl and dry combustion did not change among soil samples from different management systems, in disagreement to findings of a previous study where results of analytical C recovery were influenced by samples from different managements, supposedly because changes in lability or recalcitrance of organic matter might have affected the wet combustion reactions. A poor correlation (R² = 0.42) was found between the C:N ratios based on Walkley-Black and Kjeldahl analysis and the C:N ratios based on dry combustion analysis. The methods for C and N determination did not affect the interpretation of the effects of management systems on soil C and N stocks.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162007000500011
Editor: | São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Relação: | 10.1590/S0103-90162007000500011
Formato: | text/html
Fonte: | Scientia Agricola  v.64 n.5 2007
Fonte: | info:eu-repo/semantics/openAccess