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Radioactive Phosphorus and the Growth and Metabolic Activities of Soil Microorganisms
Author(s) -
Goring C. A. I.,
Clark Francis E.
Publication year - 1952
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/sssaj1952.03615995001600010003x
Subject(s) - loam , chemistry , phosphorus , urea , microorganism , zoology , phosphate , nitrate , incubation , environmental chemistry , carbon dioxide , phosphorite , ammonia , ammonia volatilization from urea , agronomy , soil water , bacteria , ecology , biology , biochemistry , genetics , organic chemistry
Experiments were conducted in quartz sand and in a silt loam to determine effect of differing levels of P 32 on the growth and metabolic activity of soil microorganisms. Determinations were made of carbon dioxide evolved and of numbers of microorganisms, and in some experiments, of amounts of soluble phosphate, nitrate, and ammonia. In quartz sand treated with phosphorus, dextrose, urea, and mineral salts, and with differing amounts of P 32 , activity levels of 0.005 and 0.05 mc gave no appreciable differences. At 0.5 mc P 32 per mg of P 31 , the rate of CO 2 production was reduced during the first week, and differences in the soil flora were encountered. Recovery in CO 2 production then followed, but the soil flora differences persisted throughout 3 weeks of incubation. In Seymour silt loam treated with 0.5 mc of P 32 per mg of P 31 , there was found no influence on microbial numbers or on carbon dioxide evolution, but the amounts of soluble phosphate, ammonia, and nitrate at the end of 3 weeks were lower than for 0.05‐, 0.05‐, or 0‐mc levels of treatment. When the phosphorus treatment was supplemented with dextrose and urea, no differences in the P or N status of the aliquots could be demonstrated. With dextrose and urea added and a 5.0‐mc level of activity, there was only slight reduction in CO 2 evolution and only slight differences in microbial numbers.