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The Ureolytic Microflora in a Black Spruce (Picea mariana Mill.) Humus
Author(s) -
Roberge M. R.,
Knowles R.
Publication year - 1967
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/sssaj1967.03615995003100010022x
Subject(s) - humus , urea , population , incubation , chemistry , zoology , urease , black spruce , environmental chemistry , botany , biology , soil water , ecology , biochemistry , demography , sociology , taiga
The total and the ureolytic microflora in black spruce humus from an untreated plot and from a plot fertilized with 450 kg urea‐N per ha (400 lb N per acre) 2 years before sampling was studied using incubation tests. Following the addition of 3,500 ppm of urea‐N in the laboratory the total numbers of bacteria and fungi increased on the average by 332 and 9.6%, respectively, and the numbers of ureolytic bacteria and fungi increased by 359 and 18.5%, respectively. The percentages of ureolytic bacteria and fungi both increased by only 5, indicating that the increase in population was not made up of specifically ureolytic organisms. No significant population changes occurred after 3 days of incubation, when urea hydrolysis was complete. The application of urea in the laboratory to humus from a plot treated with urea two years before sampling brought about population changes which roughly paralleled those found in humus from the untreated plot. In any particular humus layer, the population increase occurring in the field during the two years after urea application was observed to be in general greater than that occurring during the 42 days after the application of urea to the same humus layer in the laboratory.