Soil pH is a major determinant of the numbers


By jpeza - Posted on 22 Mayo 2009

Fecha Publicación: 
1 Ene 1991
Datos del paper
Autor Principal: 
J. Brockwell
Issue: 
31
Página Inicial: 
211
Página Final: 
219
Abstract: 

Measurements were made of soil pH,

frequency of occurrence of annual species of Medicago

(medics) and populations of Rhizobium meliloti at 84 sites

on 7 dominant soil groups of the Macquarie region of

central-western New South Wales. Over all sites, soil pH(0-10 cm; 1 : 5 soil: water) ranged from 5.26 to 8.07,

medic frequency from 0 to 100% and most probable

numbers of R. meliloti from undetectable to 675 0001g soil.

There was a highly significant (P<0.001) relationship

between soil pH and number of R. meliloti. AbovepH 7.0, the mean soil population of R.

meliloti was

89000Jg; below pH 6.0, it was 37/g. Medics occurred

most frequently on the more alkaline soils and with least

frequency on the more acid soils, but the relationship

between soil pH and medic frequency was weaker than

between pH and R. meliloti number. Medics were more

tolerant of low soil pH than their rhizobia were; at

2 sites, of pH 5.49 and 5.35, medics occurred at 100%

frequency but R. meliloti was undetected.

There was an indication of some acidification in

these soils over a period of 35 years but this remains to

be confirmed.

Dirección del Autor: 

CSIRO Division of Plant Industry, G.P.O. Box 1600, Canberra, A.C.T. 2601, Australia.

Keywords: 
Rhizobium meliloti ;acid soils ; alkaline soils
Coautores: 

Ann Pilka ;  Rosemary A. Holliday

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