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Ocorrência e distribuição em profundidade de Azotobacter e Beijerinckia em alguns perfis de solo da zona úmida de Pernambuco

1969; Embrapa Informação Tecnológica; Volume: 4; Issue: 1 Linguagem: Inglês

1678-3921

Adalís Bezerra Campêlo, Luiz Bezerra de Oliveira,

Soil erosion and sediment transport

In 12 soil profiles of the humid zone of the Brazilian North East, soil samples were taken between 0, and 50 cm of depth to study the occurrence of Azotobacter and Beijerinckia . Seven podzolized soils, two latosolic soils, one alluvial soil, one alluvial hydromorphic podzol were analysed. From the results the following conclusions were drawn: a) Azotobacter as well as Beijerinckia were found down to 50 cm of depth. b) Azotobacter numbers in the light textured soils remained unchanged or even increased with depth. In the profiles with heavier texture the highest numbers were found in the first or second layer, decreasing rapidly with increasing depth. c) Beijerinckia occurrence was generally more abundant in the second soil layer decreasing in the lower layers. d) Three out of 9 soils under sugar cane did not contain Beijerinckia . e) Simultaneous occurrence of Azotobacter and Beijerinckia was observed in some profiles, in sugar cane areas Azotobacter occurred in higher numbers than Beijerinckia . f) Azotobacter occurred in several soils and layers with quite low pH levels (pH 4.2). It was suggested that soil samples for microbiological studies should be taken until 50 cm of depth.