Incluye referencias bibliográficas en las páginas 93-94

Factors regulating nitrification were examined in three forests of contrasting nitrifying activity in the southern Appalachians of North Carolina, U.S.A. NH4N availability was the main factor regulating nitrification in pine/mixed-hardwood and black locust (Robinia pseudo-acacia L.)-dominated early successional forests. Litter leachate solutions from black locust had high concentrations of N and other nutrients, but their influence upon nitrification as estimated in laboratory-amended soil incubations was relatively small.

In a mature oak/hickory forest, nitrification was not stimulated by NH4N amendments, nor by amendments of black-locust litter leachate solutions. Amendments with CaCO3 and CaCl2 stimulated ammonification but did not stimulate nitrification in the soils of this forest. Laboratory incubations of soils amended with oak/hickory live leaves, litter, and forest-floor extracts suggested a possible inhibitory action on nitrification from oak leaves. Low nitrification was also found in glucose-amended laboratory incubations of black-locust soils, suggesting that an increase of the C:N ratio of the soil following amendment with extracts could be responsible for low nitrification rates.