Organic Nitrogen in New Zealand Snows

Abstract

THE nitrogen balance in New Zealand presents some rather interesting problems. In native forest and commercial exotic forests no natural source providing appreciable increments of nitrogen to the soils has yet been established. The non-symbiotic nitrogen-fixing bacteria Clostridium butyricum have been found in some tussock grassland soils by Ross¹; but their numbers are thought to be too low to account for extensive fixation. Stevenson² has presented evidence that some of the higher plants may themselves fix quantities of nitrogen [see also Nature, January 24, p. 223]. The possibility that some nitrogen is supplied via the atmosphere has been investigated by me. Snow was collected above the vegetation line to avoid possibility of contamination by plant or animal debris. This was done in preference to the more conventional rain-water sampling, which is open to large contamination errors. Since the samples were collected in the early and mid-winter there is little possibility of contamination with pollen. The analyses of snow collected from various parts of New Zealand are shown in Table 1. The samples of snow were either kept frozen until analysis, or treated on collection with toluene to arrest any bacterial activity.