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Effect of Moisture on the Survival of Rhizobium in Soil
Author(s) -
OsaAfiana L. O.,
Alexander M.
Publication year - 1979
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1979.03615995004300050022x
Subject(s) - loam , agronomy , soil water , biology , moisture , population , rhizobium , chemistry , botany , horticulture , zoology , inoculation , ecology , organic chemistry , demography , sociology
Rhizobium trifolii and Rhizobium japonicum survived in higher numbers in Collamer silt loam at 10% than at 22, 35, and 45% moisture levels. The rate of R. trifolii decline at the three higher moisture levels was initially rapid, but then the rate slowed. At 22, 35, and 45% moisture, fewer R. trifolii and R. japonicum survived in nonsterile than in sterile soil, and indigenous protozoa grew in response to addition of the root‐nodule bacteria to the nonsterile silt loam. The rate and extent of decline of both species in flooded soil were more marked if sucrose was added; in such soil, R. trifolii died more rapidly and its population reached lower numbers. Bdellovibrio was not detected as the rhizobial density declined. Butyric, acetic, propionic, and formic acids accumulated and the pH fell below 6.0 in the sugar‐amended flooded soil, but no marked accumulation of the first three microbial products and no comparable pH fall occurred in flooded soil receiving no sucrose. Liming the sugar‐amended flooded soil enhanced R. trifolii survival but still led to organc acid accumulation. The data suggest a role for protozoa at moderate moisture levels and for organic acids acting at low pH in flooded soils in the decline of Rhizobium populations.