ISSN:
1573-5036
Keywords:
Amico acids
;
Carbon dioxide evolution
;
Casein
;
Decomposition
;
Glucose
;
Humification
;
Mineralization
;
Respiration rate
;
Phenolic compounds
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary The course of the CO2 evolution rates of soil samples has been followed continuously in the absence and in the presence of various organic compounds. After an incubation period of 300 hours at 13 and 20°C the CO2 evolution from pasture soil (containing 1.76% soil organic carbon) amounted to 0.13 and 0.44μg CO2−C.g soil−1.h−1, respectively. For arable soil (containing 1.20% soil organic carbon) the rates amounted to 0.04 and 0.09 μg CO2−C.g soil−1.h−1, respectively. At 20°C larger amounts of the organic substrates added to the soil supplied with 20 μg NH4NO3−N.g soil−1 were lost as CO2 than at 13°C, indicating a higher efficiency of the growth of microorganisms at lower temperatures. In the absence of NH4NO3 the respiration rates were initially higher than in its presence, suggesting that a part of the soil microflora is inhibited by low concentrations of NH4NO3. The amounts of carbon lost were low for phenolcarboxylic acids with OH groups in the ortho position. The replacement of one of these groups by a methoxyl group resulted in a larger amount of the C lost as CO2. The replacement of the COOH group by a C=C−COOH group had a decreasing effect on the decomposition of the phenolic acids tested. The decomposition of vanillic acid,p-hydroxybenzoic acid, and of the benzoic acids with OH groups in the meta position was as complete as that of glucose, amino acids or casein. The decomposition of bacterial cells to CO2 was considerably less than that of glucose. No evidence could be obtained that the low percentage of substrate converted to CO2 at the time of maximal respiration rate was due to the decreasing diffusion rate of substrate to the microbial colonies in the soil during the consumption of substrate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02277376
Permalink
