SPADA Meeting Book

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7.2 Criteria for Selecting Soils 232 or method is being developed for deployment in a very specific region of the world, then 233 soils specific to that region should be collected. For intended uses not specific to one 234 region, Table 1 from the Organization for Economic Co-operation and Development 235 (OECD) Guideline 106 (7) provides soil characteristics covering a wide range of pH, 236 organic content, and clay content typically found in temperate geographical zones. This 237 international guideline was developed in 2000 and used by the US Environmental 238 Protection Agency (EPA) in studies concerning the mobility, distribution, and 239 degradation of chemicals in soils. Ideally, all 7 soil types from Table 1 should be 240 included in the experimental testing. If it is not possible to test all 7 types of soil, it is 241 recommended to test at least 5 soils of varying characteristics following the guidance 242 from Table 1. There may be cases in which extreme soil types (e.g., coastal soil with high 243 salt content) are required for a specific purpose. In these cases, the soils of interest should 244 be characterized and documented prior to testing, which may include additional 245 characterization tests for specific parameters of interest. As much as possible, a variety of 246 soils covering the range of the parameter of interest should be included in the 247 experimental testing. Soil selection depends on the intended use of the method or system. If an instrument

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Table 1. Guidance for selection of soil samples a

pH range (in 0.01 M CaCl 2 )

Organic carbon content (%)

Clay content (%)

Soil type

Soil texture

1 2

4.5-5.5

1.0-2.0 3.5-5.0

65-80 20-40

Clay

>7.5

Clay loam

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