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The organic carbon in New Zealand's vegetation and soils has been estimated for 1992 from updated national databases of vegetative cover and soil carbon. These databases were augmented by inclusion of vegetation and soils information for Stewart Island, and addition of carbon estimates for upland and high‐country soils of South Island. Plant biomass estimates from literature were combined with the Vegetative Cover Map of New Zealand to give an estimate of 2420 Mt carbon for vegetation carbon above and below ground, including litter and humus. More than 80% of this carbon occurs in indigenous forested ecosystems on less than 26% of the land area, with only about 5% in planted forests. Soil organic carbon estimates for two depth ranges (0–0.25 m, 0–1 m) were derived from the N.Z. Land Resource Inventory, the Soil Map of Stewart Island, and the National Soils Database. Totals were 2500 ± 77 Mt and 4260 ± 190 Mt C respectively. Yellow‐brown earths made the largest contribution, with 727 Mt C in North Island a...

A simple method was developed for measuring phosphorus (P) mineralisation in soil using an anion exchange membrane. Labile inorganic phosphate was first removed from the soil by means of the membrane. The soil samples were then filtered on GF/C papers and incubated moist under aerobic conditions for seven days at 39°C. The inorganic phosphate produced during incubation was extracted using a second extraction with the anion exchange membrane to give a measure of phosphorus mineralisation. The method was applied to 17 soil samples taken from Inceptisols, Andisols, and Spodosols under pasture and pine forest.

Humic acids from a total of 14 soils, 10 from New Zealand and 4 from Japan, were selected to provide a range from Rp to A-types. Semi-quantitative assessment of their carbon chemistry by cross polarization magic angle spinning (CPMAS)13C-nuclear magnetic resonance (NMR) revealed variations in composition that were generally related to humic acid type. Aromatic-C was the predominant form of C in most A-type humic acids whereas in Rp, P, and B-type humic acids, the aliphatic-C and aromatic-C contents were comparable. Differences in humic acid types were not always reflected in their carbon chemistry, possibly because of their mode of formation. The effects of fire on vegetation or soil organic matter may at least partly explain the occurrence of A-type humic acids in two different New Zealand soils.

Some properties of the humus in, and humic acids from, a number of volcanic ash soils from North Island, New Zealand are presented and compared with those for a range of Japanese soils. In Japanese volcanic ash soils showed, with few exceptions, much higher total organic carbon and humic acid carbon contents than the New Zealand soils. The properties of humic acids in the New Zealand volcanic ash soils were in general well differentiated from those of humic acids in volcanic ash soils from Japan, according to the Japanese system of classification. The humic acids extracted from Japanese volcanic ash soils ware blacker and apparently more humified than those from the New Zealand soils. The humic acids from a number of New Zealand soils were mostly of the B or P type, whereas those from Japanese soils were mostly of the A type. The Ch : Cf ratios were generally high in Japanese soils with humic acid having the highest degree of humification.