Worldwide Organic Soil Carbon and Nitrogen Data

This database was begun about 60 years ago with the collection and analysis of soil samples from California. Additional data came from soil surveys of Italy, Greece, Iran, Thailand, Vietnam, various tropical Amazonian areas, and U.S. forests and from the soil-survey literature. It consists of a compilation of worldwide soil carbon and nitrogen data for more than 3500 soil profiles. The data were obtained from soil surveys by Zinke (1965, 1974, 1976, 1978, 1979, and 1984) and soil-survey literature.

The main samples for laboratory analysis were collected at uniform soil-depth increments and included bulk-density determinations. Many samples reported in the survey literature did not have uniform soil increments or bulk density determinations. Only soil profiles that had been sampled either to a meter in depth or to actual depth were included in this database from soil survey literature. In literature where bulk densities were absent, densities were estimated by regressions based on organic carbon content of the soil samples associated with the profile using 1800 soil profiles for which bulk densities were known.

Methods used for analytical carbon determinations were dry combustion, wet combustion, or loss on ignition with adjustments made to the values obtained with the last two methods. Nitrogen was determined by the Kjeldahl method on the soil fine earth fraction and reported as total organic nitrogen.

The data can be used to estimate the size of the soil's organic carbon and nitrogen pools at equilibrium with natural soil-forming factors. Most of the data are from profiles associated with natural vegetation so they constitute a baseline for evaluation of the effects that disturbance or modification to natural vegetation has on soil carbon equilibrium at either a global or regional scale. The data can also be used for understanding the range and viability of soil carbon and nitrogen pools for specific ecosystems or climatic regimes.

The data on each sample are soil profile number; soil profile carbon content; soil profile nitrogen content; sampling site latitude and longitude; site elevation; profile literature reference source; and soil profile codes for Holdridge life zone, Olson ecosystem type, and parent material. These data may be used to estimate the size of the soil organic carbon and nitrogen pools at equilibrium with natural soil-forming factors.

References:

Zinke, P. J. 1965. Meditterranean Analogs of California Vegetation Types. U.S. Army National Lab. Project IK025001A129.

Zinke, P. J. 1974. Effects of Herbicides on Soils of South Vietnam. Part B: The Effects of Herbicides in South Vietnam. National Academy of Sciences, Washington, D.C. USA.

Zinke, P. J. 1976. The Banyan Trees of Kish Island, Iran. Kish Island Development Corp., Tehran, Iran.

Zinke, P. J., S. Sabhasri, and P. Kundstadter. 1978. Soil Fertility Aspects of the Lua' Forest Follow System of Shifting Cultivation. pp. 134-159. IN: Farmers in the Forest. East West Center, Univ. Hawaii, Honolulu USA.

Zinke, P. J., A. G. Strangenberger, and W. Colwell. 1979. The Fertility of the Forest. Calif. Agric. 33: 10-11.

Zinke, P. J., A. G. Strangenberger, W. M. Post, W. R. Emanuel, and J. S. Olson. 1984. Worldwide Organic Soil Carbon and Nitrogen Data. ORNL/TM-8857. Oak Ridge National Laboratory, Oak Ridge, Tennessee USA.