Effects of storage on dehydrogenase activities of soils.

Abstract The effects of four different methods of storage on the dehydrogenase activities of samples of topsoils were determined. Air drying of the samples was found to be unsatisfactory, as over half of the dehydrogenase activity was thereby lost, and further inactivation occurred on storage of the air-dried samples at room temperature (approximately 20°C). Storage of undried samples at room temperature was satisfactory for some of the topsoils over periods of less than 77 days but resulted in some loss of dehydrogenase activity after a 77-day period. Although a general prediction of the storage behaviour of undried samples could not be made because of the variability of changes shown by the individual topsoils, storage in either a refrigerator (4°C) or a deep-freeze (−20°C) appeared to be most satisfactory for retaining dehydrogenase activities. Dehydrogenase activities declined somewhat in most refrigerated samples stored for 77 days; changes were more marked in drier samples of a given soil. Freezing and thawing tended to increase the dehydrogenase activities of undried samples.