Rétention de l'azote et évolution des propriétés d'un humus brut de station de pin gris (Pinusbanksiana Lamb.) après application d'engrais azotés

Abstract

The addition of urea invitro to the coarse humus of a jack pine nursery has led to an increased pH following urea hydrolysis, with the result that the cationic exchange capacity was increased while the organic matter in the humus was partly dissolved. Furthermore, considerable losses of nitrogen due to ammonia volatilization are likely to occur following the application of urea. The use of nitrate mineral fertilizers ((NH4)2SO4, NH4NO3, or (NO3)2Ca), though these are not subject to losses through ammonia volatilization, produces a significant displacement of soil elements. Moreover, the nitrogen in such fertilizers is more prone to leaching than mineral nitrogen freed by urea hydrolysis.