Tests were made to determine the influence of the sampling and the preparatory treatment of the samples on the counting of bacteria in the soil. These proved that the present methods are very inaccurate and give rise to considerable variance in parallel determinations, to the extent even of rendering the effect of a perfected counting procedure quite negligible.
In this connection it has been stated that it is useless to aim at a minute counting of bacteria, as only the number of microbes in the ultimate soil suspension would thus be determined, whereas this suspension is by no means accurately representative of the tested soil.
For a better preparatory treatment of the samples a homogeneisation method by means of a porcelan ball mill was worked out, according to which a suspension is made of the sample with water, which method has given satisfactory results.
Finally, the determination of various chemical substances, apart from the counting of microbes, has been included in our tests. Here also an improvement in the treatment of the samples was arrived at.
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G. W. Harmsen andH. J. Verweel, Centralbl. f. Bakt. II,95, 134, 1936.
N. James andM. L. Sutherland, Canadian Journ. Res. Sect. C. Bot. Sci.17, 72 and 97, 1939.
H. G. Thornton andC. B. Taylor, Transactions of the Third Internation. Congr. of Soil Sci.I, 175, 1935.
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Harmsen, G.W. The influence of the method of sampling on the accuracy of the determination of bacterial numbers in the soil. Antonie van Leeuwenhoek 6, 178–199 (1939). https://doi.org/10.1007/BF02146186
- Satisfactory Result
- Present Method
- Ball Mill
- Chemical Substance
- Bacterial Number