CONTRIBUTION TO THE CHEMICAL COMPOSITION OF PEAT

Publisher Website
Google Scholar
Abstract
Results of investigations on the occurrence and activities of microorganisms in different peat bogs are reported, and prove conclusively that they play a most important role in formation of peat from plant remains. In lowmoor peat bogs, numbers of aerobic bacteria diminish rapidly with depth; numbers of anaerobic bacteria increase rapidly with depth. Fungi, aerobic cellulose-decomposing bacteria, and nitrifying bacteria are found in lowmoor peat bogs at or just below the surface; they diminish rapidly with depth, and disappear completely at 75-90 cm. Actinomyces are abundant at the surface of lowmoor peat; they also diminish with depth but not so rapidly as the fungi, disappearing completely at 120-150 cm. Acid sphagnum peat bogs contain an abundant flora of acid-resistant bacteria capable of growing in media at p H 4.0. In undrained sphagnum peat bogs, the numbers of bacteria, largely anaerobic forms, increase with depth, so that at 570 cm. there were found more bacteria growing on synthetic agar media than in the surface layers. The rate of decomposition of peat, as shown by evolution of CO2, is much slower than that of fresh plant residues. With increase in depth of peat there is a widening of the ratio (C/N) between C liberated as CO2 and N liberated as NH3 and nitrate. The deeper the lowmoor peat, the less active its nitrifying capacity. Certain pure cultures of fungi and actinomyces can decompose sterilized lowmoor peat as fast as the total soil population. Addition of inorganic N salt and phosphates had practically no effect on rapidity of decomposition of lowmoor and highmoor peats, because available energy and not N is the limiting factor in decomposition of peat material. The ratio between CO2 and N liberated (C/N) in the course of peat decomposition is wider in the case of highmoor sphagnum peats than in lowmoor peats. Treatment of peat with ether, toluene, and dilute HC1 followed by removal of reagent, leads to very marked increase in rapidity of peat decomposition. The action of ether and toluene is not due so much to change in balance of microbial population of peat, as to removal of waxy substances rendering the peat more readily available for action of microorganisms. Treatments differ markedly in the nature of their action on peat, because different organic complexes in the peat are affected by each type of treatment.