Nitrogen Mineralization and Nitrification: Depth Variation in Four New England Forest Soils

Abstract

AbstractNet nitrification and net nitrogen mineralization over 1 midsummer month were measured by in‐situ incubation at 14 depths in a single pit in each of four mature forest stands in New England. Nitrogen mineralization per unit of organic mass was greatest in the Oe horizon in two New Hampshire soils and in the upper A horizon in a Connecticut soil, and generally declined with increasing depth. In a Maine soil mineralization per unit of organic mass was independent of depth. Mineralization ranged from 2 to 14 kg N·ha−1 for 28 d in the four forest floors and from 3 to 12 kg N·ha−1 in the four mineral soils. Nitrification was not detected in any forest floors, but was 0.1 to 3.3 kg N·ha−1 for 28 d in the mineral soils. Both the large variation with depth and the contribution of mineral soil should not be overlooked when studying these processes.