Year of publication
2002
Excerpt
In 1997, the International Institute for Applied Systems Analysis (IIASA), Food and Agriculture Organization (FAO), and the International Soil Reference and Information Centre (ISRIC) identified the need for refinement of the agro-edaphic element in the revision of FAO's Agro-Ecological Zones (AEZ) methodology and in IIASA’s Land Use Change and Land Cover project for Europe and Northern Eurasia (LUC). The resulting study was based on the analysis of the 4353 soil profiles held in version 1.0 of ISRIC's World Inventory of Soil Emission Potential (WISE) database. It led to the development of a set of files holding ‘derived soil data for use in global and regional AEZ studies’. The study further identified several geographic, taxonomic and soil physico-chemical gaps, showing the persisting need for expanding the set of soil profile data available for this type of analyses.
Important gaps in the soil profile data were filled and the initial methodology was reviewed and refined in order to generate a revised set of physical and chemical parameter estimates for the soils units of the world, as described by the two FAO soil legends (version 1974 and 1988).
The current study uses all profiles held in WISE, version 1.0, to which have been added profiles extracted from currently available soil and terrain (SOTER) databases as well as new data from the literature. The corresponding data set holds physical and chemical attributes for over 9600 soil profiles.
Soil unit, topsoil textural class, and depth zone (0-30 cm and 30-100 cm) were used to cluster the horizon data. Criteria used are in accordance with conventions developed by FAO for use with the Soil Map of the World. Upon a screening on data ‘integrity’ and application of a statistical outlier rejection scheme, derived statistics were generated for 28 soil chemical and physical attributes. These attributes were identified as being useful for AEZ studies, crop growth simulation, and analyses of global environmental change.
Derived parameters are presented for: organic carbon; total nitrogen; C/N ratio; pH(H2O), pH(KCl), pH(CaCl2); sum of exchangeable Ca, Mg, Na and K (TEB); the ratio of exchangeable Ca/Mg and exchangeable (Ca + Mg)/K; the cation exchange capacity of the fine earth fraction (CECsoil), the effective cation exchange capacity (ECEC), apparent cation exchange capacity of the clay fraction (CECap), and cation exchange capacity of the clay fraction corrected for the contribution of organic matter (CECclay); base saturation; aluminium saturation; CaCO3 content; gypsum content; exchangeable sodium percentage (ESP); electrical conductivity (ECe); bulk density; total porosity; weight percent of sand, silt and clay; gravel content; and, available water held between –5 kPa and -1500 kPa, –10 kPa and -1500 kPa, and –33kPa and -1500 kPa, respectively. A number of statistics is presented for each of these parameters, including number of observations, means, coefficients of variation, 95% confidence intervals, medians, and medians of absolute deviations. Simple taxotransfer rules are introduced to fill gaps that remained in the derived data, notably where sufficient measured data were lacking for particular attributes and soil units.
The attached set of derived soil parameters should be seen as the best possible estimates, based on the present selection of soil profiles and adopted data clustering procedure. The derived data set is considered appropriate for use in studies at a regional to global scale (< 1:250,000). Correlation of soil analytical data, however, must be done more accurately when more precise scientific research is considered.
Keywords: derived soil parameters; environmental modelling; FAO soil legend; WISE soil database; taxotransfer rules
Important gaps in the soil profile data were filled and the initial methodology was reviewed and refined in order to generate a revised set of physical and chemical parameter estimates for the soils units of the world, as described by the two FAO soil legends (version 1974 and 1988).
The current study uses all profiles held in WISE, version 1.0, to which have been added profiles extracted from currently available soil and terrain (SOTER) databases as well as new data from the literature. The corresponding data set holds physical and chemical attributes for over 9600 soil profiles.
Soil unit, topsoil textural class, and depth zone (0-30 cm and 30-100 cm) were used to cluster the horizon data. Criteria used are in accordance with conventions developed by FAO for use with the Soil Map of the World. Upon a screening on data ‘integrity’ and application of a statistical outlier rejection scheme, derived statistics were generated for 28 soil chemical and physical attributes. These attributes were identified as being useful for AEZ studies, crop growth simulation, and analyses of global environmental change.
Derived parameters are presented for: organic carbon; total nitrogen; C/N ratio; pH(H2O), pH(KCl), pH(CaCl2); sum of exchangeable Ca, Mg, Na and K (TEB); the ratio of exchangeable Ca/Mg and exchangeable (Ca + Mg)/K; the cation exchange capacity of the fine earth fraction (CECsoil), the effective cation exchange capacity (ECEC), apparent cation exchange capacity of the clay fraction (CECap), and cation exchange capacity of the clay fraction corrected for the contribution of organic matter (CECclay); base saturation; aluminium saturation; CaCO3 content; gypsum content; exchangeable sodium percentage (ESP); electrical conductivity (ECe); bulk density; total porosity; weight percent of sand, silt and clay; gravel content; and, available water held between –5 kPa and -1500 kPa, –10 kPa and -1500 kPa, and –33kPa and -1500 kPa, respectively. A number of statistics is presented for each of these parameters, including number of observations, means, coefficients of variation, 95% confidence intervals, medians, and medians of absolute deviations. Simple taxotransfer rules are introduced to fill gaps that remained in the derived data, notably where sufficient measured data were lacking for particular attributes and soil units.
The attached set of derived soil parameters should be seen as the best possible estimates, based on the present selection of soil profiles and adopted data clustering procedure. The derived data set is considered appropriate for use in studies at a regional to global scale (< 1:250,000). Correlation of soil analytical data, however, must be done more accurately when more precise scientific research is considered.
Keywords: derived soil parameters; environmental modelling; FAO soil legend; WISE soil database; taxotransfer rules