Étude in vitro sur la minéralisation de l'azote organique dans les humus forestiers. I. Influence de litières forestières

The present work was undertaken to study the influence of some forest litters on the course of nitrogen mineralisation in various types of forest humus. Under the controlled environmental conditions used, nitrogen mineralisation appears especially active in raw humus developped under balsam fir stands of Northern Quebec. Although it is rapid in M.ull humus, nitrification is apparently low in Moder and is normally inoperant in raw humus ; it is however markedly enhanced by liming in the last two types of humus. The seventeen litters incubated with some of the humus vary greatly in their ability to supply available nitrogen. Some considerably enhance nitrogen immobilisation, regardless of the humus form into which these are incorporated. Such a behaviour is not imputable only to the C/N ratio of the litters but appears to largely depend on the susceptivity to enzymic breakdown of their carbohydrates and nitrogenous constituents. A litter sample originating from a sugar maple stand where an acid Moder has developped, appears to contain substances capable of impeding the mineralisation of protein nitrogen.