Influence of Soil Characteristics on the Survival of Rhizobium in Soils Undergoing Drying

Abstract
A study was conducted to establish whether certain soil characteristics could be correlated with the extent of survival of Rhizobium as the soils underwent drying. The numbers of R. meliloti and R. phaseoli fell markedly as the soils dried, but their abundance declined slowly in the soils maintained in an air‐dry state. The number of surviving cells increased if these bacteria were added to sterile soil and allowed to grow before desiccation was extensive. Survival of both species was poor in soils of pH values below 5.7. The number of survivors of R. meliloti but not R. phaseoli decreased as the content of clay and of water at 15 bar suction increased. At organic matter levels below but not above 2 to 3%, the abundance of survivors of these rhizobia was related to the organic carbon content of the soil. Survival of R. phaseoli was inversely related to the content of total available aluminum in the soils, but the number of survivors of the two species was not correlated with the available phosphorus levels.
Funding Information
  • United States Agency for International Development (AID/csd‐2834)

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