ATIVIDADE MICROBIANA E PROPRIEDADES BIOQUÍMICAS do SOLO RESULTANTES da APLICAÇÃO DE GESSO AGRÍCOLA NA CULTURA do REPOLHO
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Data
1997-09-01
Autores
NAHAS, E. [UNESP]
DELFINO, J.H. [UNESP]
ASSIS, L.C. [UNESP]
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Editor
Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ)
Resumo
Este estudo investigou o impacto da aplicação de gesso agrícola e de uma fonte rica em enxofre sobre as características microbianas e bioquímicas de um latossolo vermelho escuro cultivado com repolho. As aplicações de gesso foram de 134, 268 e 402 kg de S/ha. Foram incluídos um tratamento controle, sem enxofre, um contendo a adubação normal de sulfato de amônio (402kg de S/ha) e outro com adubo verde (20t/ha de lab-lab, peso seco). em resposta a adições crescentes de enxofre no solo verificou-se que enquanto o número de bactérias totais aumentou, o número de bactérias Gram-negativas diminuiu. Os demais grupos de microrganismos, Bacillus spp, actinomicetos e fungos, não variaram significativamente ou não apresentaram uma resposta satisfatória. O aumento do número de bactérias totais, em relação ao controle, foi de 29 a 60% na rizosfera e de 15 a 107% na não-rizosfera, respectivamente. O número de microrganismos na rizosfera foi de 5 a 251 % superior ao da não-rizosfera. A biomassa microbiana da rizosfera aumentou nos tratamentos com sulfato de amônio e adubo verde, permanecendo invariável na não-rizosfera. Confirmando os resultados da contagem microbiana, a biomassa microbiana também aumentou na rizosfera em relação à da não-rizosfera. A atividade da desidrogenase e da urease aumentou em relação ao controle, não se constatando, no entanto, efeito na atividade da arilsulfatase. A produção de repolho foi superior ao controle de 52,5 a 81,1 %. Concentrações crescentes de enxofre foram observadas no solo e na parte aérea do repolho.
The present study investigated the impact of the application of gypsum and of a sulfur-rich source on the microbial and biochemical characteristics of a dark red latossol used for cabbage cultivation. Gypsum was applied in amounts of 134, 268, and 402 kg S/ha. The following controls were included: a treatment with no sulfur; fertilization with ammonium sulfate (402 kg S/ha); and organic matter (20 t/ha lab-lab, dry weight). Application of increasing sulfur doses to the soil led to an increase in total number of bacteria and a decrease in Gram-negative bacteria. The remaining groups of microorganisms, Bacillus spp, actinomycetes and fungi, did not vary significantly or did not present a satisfatory response. The increase in total number of bacteria compared to control was 29 to 60% in the rhizosphere and 15 to 107% in the non-rhizosphere, with the number of microorganisms in the rhizosphere exceeding the number of microorganisms in the non-rhizosphere by 5 to 251%. The microbial biomass of the rhizosphere increased in the treatments with ammonium sulfate and organic matter and was unchanged in the non-rhizosphere. In agreement with microbial count data, the microbial biomass also increased in the rhizosphere compared to the non-rhizosphere. Dehydrogenase and urease activity increased in comparison to the control, although no effect was observed on arylsulfatase activity. Cabbage production on treated soil was 52.2 to 81.1% higher as compared to the control. Increasing sulfur concentrations were observed in the soil and in the cabbage aerial portion.
The present study investigated the impact of the application of gypsum and of a sulfur-rich source on the microbial and biochemical characteristics of a dark red latossol used for cabbage cultivation. Gypsum was applied in amounts of 134, 268, and 402 kg S/ha. The following controls were included: a treatment with no sulfur; fertilization with ammonium sulfate (402 kg S/ha); and organic matter (20 t/ha lab-lab, dry weight). Application of increasing sulfur doses to the soil led to an increase in total number of bacteria and a decrease in Gram-negative bacteria. The remaining groups of microorganisms, Bacillus spp, actinomycetes and fungi, did not vary significantly or did not present a satisfatory response. The increase in total number of bacteria compared to control was 29 to 60% in the rhizosphere and 15 to 107% in the non-rhizosphere, with the number of microorganisms in the rhizosphere exceeding the number of microorganisms in the non-rhizosphere by 5 to 251%. The microbial biomass of the rhizosphere increased in the treatments with ammonium sulfate and organic matter and was unchanged in the non-rhizosphere. In agreement with microbial count data, the microbial biomass also increased in the rhizosphere compared to the non-rhizosphere. Dehydrogenase and urease activity increased in comparison to the control, although no effect was observed on arylsulfatase activity. Cabbage production on treated soil was 52.2 to 81.1% higher as compared to the control. Increasing sulfur concentrations were observed in the soil and in the cabbage aerial portion.
Descrição
Palavras-chave
gesso agrícola, bactérias, fungos, desidrogenase, urease, arilsulfatase, gypsum, bacteria, fungi, dehydrogenase, urease, arylsulfatase
Como citar
Scientia Agricola. São Paulo - Escola Superior de Agricultura Luiz de Queiroz, v. 54, n. 3, p. 160-166, 1997.