Atributos microbiológicos de um latossolo bruno submetido a diferentes sistemas de manejo e calagem / Soil microbiological atributtes of a brown latosol submitted to different management systems and liming

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

28/02/2007

RESUMO

This work was conducted in Guarapuava, state of Paraná, in a southern brazilian oxisol, in a trial established in 1978. The aim of this work was to analyse the effect of different soil management systems and liming on the microbial biomass and its activity related to C and N in the soil. The managment systems evaluated were: no-tillage with lime incorporated (PDinc); no-tillage without liming (PDsem); reduced tillage system with lime incorporated (PRinc); reduced tillage system without liming (PRsem); conventional tillage with lime incorporated (PCinc), and; conventional tillage without liming (PCsem). Soil samples were collected in the 0-10 cm soil layer, at two distinct times (january and august, 2006), in order to quantify the levels of the microbial biomass carbon (MBC), by the wet oxidation method after fumigation for 24 hours; total organic carbon (TOC), by the chemical analyses with wet sulfocromic oxidation; microbial biomass of nitrogen (MBN) and total nitrogen (TN), both by distillation and digestion; MBC:TOC ratio, and MBN:TN ratio. The microbial activity estimation was determined through the microbial basal respiration of the soil samples (evoluted C-CO2) according to Jäggi. The results of C-CO2 and MBC were used to calculate the metabolic quotient (qCO2) that represents the content of C-CO2 evoluted in a range time for unity of microbial C. The MBC determination was performed by titulation, and MBN by pre-digestion and distillation according to Kjeldahl method. The colonization and hyphal length were also evaluated according to the methodology proposed by Koske &Gemma and Melloni, respectively. The C-CO2 and qCO2 showed the higher rates in conventional tillage, and the lower in No-tillage, what allows discriminate the systems in relation to C sustainability in the soil. The contents of MBC varied among the managment system, and the contents of organic-C did not vary among tillage systems, varying only between sampling times. The three factors (managment system, liming and sampling times) interacted to determine the MBN variation and MBC:MBN ratio. The mycorrhizal colonization and hyphal length were higher in the no-tillage system.

ASSUNTO(S)

sistemas de manejo do solo calagem biomassa microbiana atividade microbiana micorrizas agronomia soil managment systems liming microbial biomass microbial activity mycorrhiza

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