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Provedor de dados:  Scientia Agricola
País:  Brazil
Título:  Humic substances and its distribution in coffee crop under cover crops and weed control methods
Autores:  Martins,Bruno Henrique
Araujo-Junior,Cezar Francisco
Vieira,Karen Mayara
Data:  2016-08-01
Ano:  2016
Palavras-chave:  UV-Vis spectroscopy
Conservation agriculture
Soil organic matter
Carbon content
Chemical fractionating
Resumo:  ABSTRACT Humic substances (HS) comprise the passive element in soil organic matter (SOM), and represent one of the soil carbon pools which may be altered by different cover crops and weed control methods. This study aimed to assess HS distribution and characteristics in an experimental coffee crop area subjected to cover crops and cultural, mechanical, and chemical weed control. The study was carried out at Londrina, in the state of Paraná, southern Brazil (23°21’30” S; 51°10’17” W). In 2008, seven weed control/cover crops were established in a randomized block design between two coffee rows as the main-plot factor per plot and soil sampling depths (0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm) as a split-plot. HS were extracted through alkaline and acid solutions and analyzed by chromic acid wet oxidation and UV-Vis spectroscopy. Chemical attributes presented variations in the topsoil between the field conditions analyzed. Cover crop cutting and coffee tree pruning residues left on the soil surface may have interfered in nutrient cycling and the humification process. Data showed that humic substances comprised about 50 % of SOM. Although different cover crops and weed control methods did not alter humic and fulvic acid carbon content, a possible incidence of condensed aromatic structures at depth increments in fulvic acids was observed, leading to an average decrease of 53 % in the E4/E6 ratio. Humin carbon content increased 25 % in the topsoil, particularly under crop weed-control methods, probably due to high incorporation of recalcitrant structures from coffee tree pruning residues and cover crops.
Tipo:  Info:eu-repo/semantics/article
Idioma:  Inglês
Editor:  São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Relação:  10.1590/0103-9016-2015-0214
Formato:  text/html
Fonte:  Scientia Agricola v.73 n.4 2016
Direitos:  info:eu-repo/semantics/openAccess

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