The Influence of Available Nitrogen on the Fermentation of Cellulose in the Soil

The rate of decay in relation to soil types and vegetative covering in Glamorgan

“…The course of decomposition as indicated by CO 2 evolution depends not only on the soil but also, as to a far greater extent, on the nature of the added organic material. In Gainey's investigations (7) where the same soil (a silt loam) was used throughout, the maximum C0 2 evolution on adding 1 per cent, cottonseed meal, was attained during the second 24 hours of incubation, although it should be borne in mind "that the day the experiment was begun cannot be regarded as a full 24 hours, since it required at least half a work day to set the experiment up 1 ." With 1 per cent, dried blood which has a nitrogen content double that of cottonseed meal, Gainey found that the maximum CO 2 evolution took place between the 6th and 8th days.…”

“…The following properties of crushed linseed would lead us to suppose that when added to soil it will undergo rapid decomposition: (a) Crushed condition and easy accessibility of mucilage and aleurone grains (8). (b) The ratio of available carbohydrates; lignin (fibre) is about 4-164 1 . Norman (19) has shown that when the ratio of the available carbohydrates (energy factor) to lignin (resistant factor) is above 4, decomposition will be rapid, but below 3 the decomposition will be slow, (c) 6 per cent, of the total carbohydrate content is in the form of readily attacked mucilage (9).…”

“…Pedology. The only published work on the soils of Glamorgan is that of the "Soil survey of Wales" (27) in which only the soils of the Vale of Glamorgan are discussed 1 . This work was not carried out from a purely scientific point of view, but from the point of view of agriculture, the soils being so arranged as to bring out their relative agricultural values.…”

5. The Chemical Composition of Soil Organic Matter as Related to its Effectiveness1

“…The complexity of the material also affected the process, as the simpler substances are capable of being attacked by many organisms, while the more complex are decomposed by relatively few due to the resistant compounds present. Anderson (4) shows that for cellulose decomposition the rate increases with the increase in available nitrogen until the latter is present in amounts sufficient for the maximum growth of the micro-organisms. In order to obtain some information as to the availability of the nitrogen in the soil organic matter for this process, he carried out several experiments using a number of the cleavage products of proteins.…”

“…There may also be such organic acids as ac€tic, propionic, malic, and others, but these probably would not accumulate to any extent in normal soils. 4…”