Enzyme activity and microbial biomass in an Oxisol amended with sewage sludge contaminated with nickel
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Data
2007-02-01
Autores
Revoredo, Marcos Donizeti [UNESP]
Melo, Wanderley José de [UNESP]
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ISSN da Revista
Título de Volume
Editor
Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ)
Resumo
O comportamento do níquel em solos de regiões tropicais, principalmente quando adicionado através de lodos de esgoto, ainda é pouco conhecido. O estudo foi conduzido em casa de vegetação, localizada no município de Jaboticabal, Estado de São Paulo, Brasil, com o objetivo de avaliar o impacto da aplicação de lodo de esgoto contaminado com níquel (329, 502, 746 e 1119 mg kg-1, base seca) sobre a atividade enzimática e a biomassa microbiana de um solo cultivado com sorgo. As amostras de solo foram coletadas em duas épocas (início e final do experimento). O delineamento utilizado foi o inteiramente casualizado, com cinco tratamentos (testemunha + quatro doses de Ni no lodo de esgoto) e quatro repetições. O C e o N da biomassa microbiana e a atividade das fosfatases ácida e alcalina foram indicadores sensíveis na avaliação do impacto da aplicação do lodo de esgoto contaminado com níquel no solo. Houve correlação significativa e positiva entre os teores totais e extraíveis de Ni com o C da biomassa microbiana e negativa com a relação C/N da biomassa microbiana nas duas épocas de amostragem. O N da biomassa microbiana correlacionou-se positivamente com os teores totais e extraíveis de Ni (Mehlich 1). A atividade da fosfatase ácida correlacionou-se negativamente com o Ni total e a atividade da fosfatase alcalina com os teores de Ni total e Ni extraível ao final do experimento.
The role of nickel in soils of tropical areas under the application of sewage sludge is still not very well known. This study was carried out under greenhouse conditions in Jaboticabal, São Paulo State, Brazil, with the objective of evaluating the impact of the application of sewage sludge previously contaminated with rates of nickel (329, 502, 746 and 1119 mg kg-1, dry basis) on a soil cropped with sorghum, in relation to soil enzyme activity and soil microbial biomass. Soil samples were collected at the beginning and the end of the experiment. The experimental design was completely randomized, with five treatments (control and four rates of Ni in the sewage sludge) and four replications. C and N of the soil microbial biomass and enzyme activities (acid and alkaline phosphatases) were sensitive indicators for impact evaluation caused by sewage sludge contaminated with nickel. There were positive correlations between total and extractable nickel (Mehlich 1) with C-microbial biomass and negative with the microbial C/N relationship. N-microbial biomass correlated positively with total and extractable Ni at the last sampling. At the end of the experiment, the acid phosphatase activity correlated negatively with total Ni while the alkaline phosphatase correlated with both forms of the metal.
The role of nickel in soils of tropical areas under the application of sewage sludge is still not very well known. This study was carried out under greenhouse conditions in Jaboticabal, São Paulo State, Brazil, with the objective of evaluating the impact of the application of sewage sludge previously contaminated with rates of nickel (329, 502, 746 and 1119 mg kg-1, dry basis) on a soil cropped with sorghum, in relation to soil enzyme activity and soil microbial biomass. Soil samples were collected at the beginning and the end of the experiment. The experimental design was completely randomized, with five treatments (control and four rates of Ni in the sewage sludge) and four replications. C and N of the soil microbial biomass and enzyme activities (acid and alkaline phosphatases) were sensitive indicators for impact evaluation caused by sewage sludge contaminated with nickel. There were positive correlations between total and extractable nickel (Mehlich 1) with C-microbial biomass and negative with the microbial C/N relationship. N-microbial biomass correlated positively with total and extractable Ni at the last sampling. At the end of the experiment, the acid phosphatase activity correlated negatively with total Ni while the alkaline phosphatase correlated with both forms of the metal.
Descrição
Palavras-chave
Heavy metal, biosolid, Acid phosphatase, Alkaline phosphatase, Sorghum, metal pesado, Biossólido, fosfatase ácida, fosfatase alcalina, Sorgo
Como citar
Scientia Agricola. São Paulo - Escola Superior de Agricultura Luiz de Queiroz, v. 64, n. 1, p. 61-67, 2007.