Nitrification and ammonification in acid forest litter and humus as affected by peptone and ammonium-n amendment
1986; Elsevier BV; Volume: 18; Issue: 1 Linguagem: Inglês
10.1016/0038-0717(86)90102-1
ISSN1879-3428
Autores Tópico(s)Peatlands and Wetlands Ecology
ResumoSamples of strongly acid forest litter and humus from beneath Sitka spruce, heather, Scots pine and larch from two sites in north-east Scotland were incubated aerobically at 20°C in the laboratory. At the Glen Tanar site, spruce litter and larch humus showed significant nitrification and ammonification whereas spruce humus and Scots pine humus produced only NH4+-N. Heather humus showed no net mineralization. At the Fetteresso site, application of fertilizer N, P and K to Sitka spruce up to 3 yr previously, significantly stimulated the production of NO3−-N in both litter and humus. Amendment of the samples with organic N as peptone caused significant increases in NO3−-N production in those samples that already showed nitrification. The increases in NO3−-N generally represented a low proportion of the added peptone-N. Amendment with NH4+-N as (NH4)2SO4 either had no effect or significantly reduced NO3−-N production (in larch humus). The results suggest the occurrence of heterotrophic nitrification in some of these forest samples. Net immobilization of NH4+-N was typically greater in NH4+-N amended than in peptone amended samples, except for heather humus which showed complete immobilization of both N sources. Total mineral N produced at the end of the aerobic incubation was correlated (P < 0.01) with NH4+-N produced during a 30-day anaerobic incubation at 30°C. Net NO3−-N production was greater in litter than in the corresponding humus samples and was correlated (P < 0.001) with initial organic N soluble in 1 m KCl.
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