População microbiana total e solubilizadora de fosfato em solo submetido a diferentes sistemas de cultivo
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Data
2000-10-01
Autores
BARROTI, GIOVANE
NAHAS, ELY [UNESP]
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Editor
Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
Resumo
O objetivo deste trabalho foi avaliar o efeito de diferentes espécies de plantas, fontes de fósforo e calagem sobre a população microbiana total e solubilizadora de fosfato. Foram isolados fungos e bactérias capazes de solubilizar hidroxiapatita, proporcionando P solúvel. O experimento utilizado foi em blocos ao acaso com fatorial 3x3x2. E os fatores avaliados foram espécies de plantas (controle, braquiária e guandu), fertilizantes (controle, superfosfato simples e fosfato de rocha, ambos na dose de 400 kg ha-1 de P(2)0(5) ) e calagem (com e sem calcário). A população bacteriana cresceu pelo efeito da calagem, e a de fungos aumentou, independentemente da calagem, nas parcelas cultivadas com braquiária e fertilizadas com superfosfato. Foi constatado incremento de biomassa-P microbiana sobre o controle por influência da braquiária (23,9%), do superfosfato (30,9%) e da calagem (46,9%). O número de bactérias solubilizadoras foi favorecido pela calagem ou pelo plantio de guandu adubado com fosfato natural ou com braquiária sem adubação. Os fungos solubilizadores aumentaram na ausência de planta ou de adubação e na presença de guandu com fosfato natural. Finalmente, a calagem favoreceumais o crescimento dos fungos solubilizadores, em comparação com o controle, nos tratamentos fosfato natural, braquiária ou guandu.
The objective of the present study was to evaluate the effect of different plant species, phosphorus sources, and liming on the total microbial and phosphate-solubilizing population. In order to achieve that, bacteria and fungi capable of solubilizing hydroxyapatite providing available P were isolated. An experiment was carried out in a randomized factorial block design 3x3x2. The factors evaluated were plant species (control, Brachiaria ruziziensis and Cajanus cajan), fertilizers (control, simple superphosphate and rock phosphate, both at the dose of 400 kg ha-1 of P(2)0(5)) and liming (with and without lime). While the bacterial population increased due to the effect of liming, the fungal population also increased independently of liming in the soil cultivated with B. ruziziensis and fertilized with superphosphate. An increase of the microbial biomass-P compared to the control was observed under the influence of B. ruziziensis (23.9%), superphosphate (30.9%) or liming (46.9%). The number of solubilizing bacteria was favored by liming andby the planting of C. cajan fertilized with rock phosphate or with unfertilized B. ruziziensis. The solubilizing fungi increased in the absence of plants or fertilization and in the presence of C. cajan fertilized with rock phosphate. Finally, liming enhanced more the growth of solubilizing fungi than did the control in the treatments using rock phosphate, B. ruziziensis or C. cajan.
The objective of the present study was to evaluate the effect of different plant species, phosphorus sources, and liming on the total microbial and phosphate-solubilizing population. In order to achieve that, bacteria and fungi capable of solubilizing hydroxyapatite providing available P were isolated. An experiment was carried out in a randomized factorial block design 3x3x2. The factors evaluated were plant species (control, Brachiaria ruziziensis and Cajanus cajan), fertilizers (control, simple superphosphate and rock phosphate, both at the dose of 400 kg ha-1 of P(2)0(5)) and liming (with and without lime). While the bacterial population increased due to the effect of liming, the fungal population also increased independently of liming in the soil cultivated with B. ruziziensis and fertilized with superphosphate. An increase of the microbial biomass-P compared to the control was observed under the influence of B. ruziziensis (23.9%), superphosphate (30.9%) or liming (46.9%). The number of solubilizing bacteria was favored by liming andby the planting of C. cajan fertilized with rock phosphate or with unfertilized B. ruziziensis. The solubilizing fungi increased in the absence of plants or fertilization and in the presence of C. cajan fertilized with rock phosphate. Finally, liming enhanced more the growth of solubilizing fungi than did the control in the treatments using rock phosphate, B. ruziziensis or C. cajan.
Descrição
Palavras-chave
Brachiaria ruziziensis, Cajanus cajan, Bacteria, fungi, biomass, braquiária, Guandu, Bactérias, Fungos, Biomassa
Como citar
Pesquisa Agropecuária Brasileira. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Informação TecnológicaPesquisa Agropecuária Brasileira, v. 35, n. 10, p. 2043-2050, 2000.