Accuracy and reliability of pedotransfer functions as affected by grouping soils

被引:132
作者
Pachepsky, YA [1 ]
Rawls, WJ
机构
[1] USDA ARS, Remote Sensing & Modeling Lab, Beltsville, MD 20705 USA
[2] Duke Univ Phytotron, Durham, NC 27708 USA
[3] USDA ARS, Hydrol Lab, Beltsville, MD 20705 USA
关键词
D O I
10.2136/sssaj1999.6361748x
中图分类号
S15 [土壤学];
学科分类号
0903 ; 090301 ;
摘要
Pedotransfer functions (PTFs; i,e., dependencies of soil water retention and soil hydraulic conductivity on basic soil parameters available from soil surveys) are widely used to predict soil functioning in agricultural and environmental systems. The reliability of PTFs needs to be assessed by examining the correspondence between measured and estimated data for data set(s) other than the one used to develop a PTF, Our objective was to see whether grouping according to taxonomic unit, soil moisture regime, soil temperature regime, and soil textural class would improve both PTF accuracy and reliability, We estimated soil water contents at matrix potentials of -33 kPa and -1500 kPa for the 447 soil samples from the Oklahoma National Resource Conservation Service database. Dry bulk density, the ratio of cation-exchange capacity (CEC) to clay content, and contents of clay, sand, coarse fragments, and organic matter were used as predictors. The Group Method of Data Handling (GMDH) was used to develop PTFs, To assess accuracy and reliability of the PTFs, we used cross-validation; i.e., repeated random splitting of the data set into subsets for development and validation. The PTF accuracy and reliability was quantified by the root mean square error in the development and validation data set, respectively, Grouping improved the accuracy of PTFs in most cases. None of the grouping criteria proved to be clearly superior, Although PTFs developed from the groups were more accurate than the PTFs developed from the whole database, they were not more reliable. improving PTF reliability may be an issue distinctly different from improving PTF accuracy.
引用
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页码:1748 / 1757
页数:10
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