Características biológicas do solo indicadoras de qualidade após dois anos de aplicação de biossólido industrial e cultivo de milho
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Data
2007-10-01
Autores
Trannin, Isabel Cristina de Barros [UNESP]
Siqueira, José Oswaldo
Moreira, Fátima Maria de Souza
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
A utilização agrícola de biossólidos tem sido muito incentivada, mas, como esses resíduos apresentam composição química variada, o valor agronômico e os efeitos sobre características indicadoras de qualidade do solo precisam ser avaliados caso a caso, a fim de estabelecer normas de segurança para uso desses materiais. Neste trabalho foram avaliadas características biológicas, após a aplicação, por dois anos consecutivos, de doses crescentes (0, 6, 12, 18 e 24 t ha-1 base seca) de um biossólido gerado por uma indústria de fibras e resinas PET e da adubação mineral completa no cultivo de milho, em um Cambissolo distrófico, comparados aos de uma área adjacente, sob Brachiaria sp. e sem cultivo nos últimos 10 anos, usada como referência. Os valores de C e N da biomassa microbiana, a respiração basal e as atividades das enzimas urease e beta-glicosidase e da hidrólise do diacetato de fluoresceína (FDA) aumentaram, enquanto a atividade da fosfatase ácida diminuiu com a elevação das doses de biossólido, porém estas não tiveram efeito sobre o quociente metabólico (qCO2). A diminuição da atividade da fosfatase se deveu ao aumento da disponibilidade de P no solo, não caracterizando efeito adverso da aplicação do biossólido. Com aplicação de 12 t ha-1 de biossólido (recomendação agronômica), a respiração e a hidrólise da FDA foram maiores e a atividade da fosfatase foi menor que a obtida no solo com adubação mineral, mas as demais características avaliadas não diferiram entre estes tratamentos. A colonização micorrízica de Brachiaria sp. não diferiu entre plantas de crescimento espontâneo nas parcelas anteriormente cultivadas com milho e aquelas da área adjacente. Apesar do menor número de esporos, verificou-se enriquecimento de espécies de fungos micorrízicos arbusculares (FMAs) nas parcelas cultivadas. O carbono orgânico (Corg) e a biomassa microbiana apresentaram alta correlação com os demais parâmetros avaliados, indicando que as alterações na quantidade e qualidade da matéria orgânica, promovidas pela aplicação do biossólido, refletiram na dinâmica da microbiota e influenciaram positivamente os parâmetros biológicos de qualidade do solo.
The agricultural use of biosolids has been stimulated, however, as the chemical composition of these residues is varied, the agronomic value and effects on soil quality characteristics need to be individually assessed in order to establish safety norms for their application. The present work evaluated biological characteristics after the application for two consecutive years of increasing doses (0, 6, 12, 18 and 24 t ha-1 dry matter) of biosolid generated by a PET fiber and resin industry. There was also a complete mineral fertilizer treatment in corn cultivation in a Cambisol, compared to an adjacent area under Brachiaria sp. without cultivation for the last ten years. The microbial biomass C and N, basal respiration and urease, beta-glucosidase and fluorescein diacetate hydrolysis activities were increased, while the acid phosphatase activity was reduced with the increase of biosolid rates. The different biosolid doses had no effect on the microbial metabolic quotient (qCO2). The decrease in phosphatase activity was related to the increase in phosphorus availability in soil rather than representing an adverse effect to biosolid application. With the application of 12 Mg ha-1 biosolid (agronomic recommendation), the basal respiration and fluorescein diacetate hydrolysis were higher and the phosphatase activity lower than in the soil that received mineral fertilizer, while the other parameters were not affected by these treatments. The mycorrhizal colonization of Brachiaria sp. did not differ among spontaneously growing plants in plots previously cultivated with corn and those of adjacent area. In spite of the lower spore number, an enrichment in the arbuscular mycorrhizal fungi species was observed in the cultivated plots. Organic carbon and microbial biomass were highly correlated with the other characteristics. This indicates that the changes in the amount and quality of soil organic matter, as a result of biosolid application, altered microbial dynamics and influenced the biological parameters of soil quality positively.
The agricultural use of biosolids has been stimulated, however, as the chemical composition of these residues is varied, the agronomic value and effects on soil quality characteristics need to be individually assessed in order to establish safety norms for their application. The present work evaluated biological characteristics after the application for two consecutive years of increasing doses (0, 6, 12, 18 and 24 t ha-1 dry matter) of biosolid generated by a PET fiber and resin industry. There was also a complete mineral fertilizer treatment in corn cultivation in a Cambisol, compared to an adjacent area under Brachiaria sp. without cultivation for the last ten years. The microbial biomass C and N, basal respiration and urease, beta-glucosidase and fluorescein diacetate hydrolysis activities were increased, while the acid phosphatase activity was reduced with the increase of biosolid rates. The different biosolid doses had no effect on the microbial metabolic quotient (qCO2). The decrease in phosphatase activity was related to the increase in phosphorus availability in soil rather than representing an adverse effect to biosolid application. With the application of 12 Mg ha-1 biosolid (agronomic recommendation), the basal respiration and fluorescein diacetate hydrolysis were higher and the phosphatase activity lower than in the soil that received mineral fertilizer, while the other parameters were not affected by these treatments. The mycorrhizal colonization of Brachiaria sp. did not differ among spontaneously growing plants in plots previously cultivated with corn and those of adjacent area. In spite of the lower spore number, an enrichment in the arbuscular mycorrhizal fungi species was observed in the cultivated plots. Organic carbon and microbial biomass were highly correlated with the other characteristics. This indicates that the changes in the amount and quality of soil organic matter, as a result of biosolid application, altered microbial dynamics and influenced the biological parameters of soil quality positively.
Descrição
Palavras-chave
lodo de esgoto, biomassa microbiana, respiração, quociente metabólico (qCO2), enzimas do solo, diacetato de fluoresceína (FDA), beta-glicosidase, urease, fosfatase, fungos micorrízicos arbusculares (FMAs), sewage sludge, microbial biomass, soil respiration, microbial metabolic quotient (qCO2), microbial activity, soil enzymes, fluorescein diacetate (FDA), beta-glucosidase, urease, phosphatase, arbuscular mycorrhizal fungi
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 31, n. 5, p. 1173-1184, 2007.