SPADA Draft Documents

storage for more than 21 days at 4°C begins to impact some of the measurable microbial 453 activities (8).

454 455 456

8.9 Manufactured Soil 457 studies. However, a manufactured soil is not recommended for full testing as it does not 458 recapitulate all of the properties of real soil. Manufactured soils are prepared using 459 defined recipes. As such, they do not include soil organisms that are an essential part of 460 the soil. Microorganisms impact nutrient cycling, soil structure, water retention and other 461 processes that naturally occur in soil. The manufactured soil recipes provided here use 462 only 1 clay mineral. There are over 2,000 known minerals with 20 major minerals that 463 can be found in soil. 464 All materials that will be used to prepare manufactured soil should be pretreated as 465 follows. Wash in dish detergent and tap water; thoroughly rinse with hot tap water to 466 remove soap; rinse four times with ASTM-compliant Type 2 purified water (>5 MΩ 467 cm@25ºC; TOC <30 ppb ); and rinse three times with ASTM-compliant Type 1 purified 468 water (18 MΩ cm@25ºC; TOC <10 ppb). Additionally, all glassware and plasticware 469 should be rinsed with 0.1 N nitric acid after the Type 2 water rinses and prior to the Type 470 1 water rinses. 471 It is recommended that two manufactured soils be prepared consisting of sand and 472 montmorillonite clay with and without humus. The sand component should be purified 473 silica sand (SiO 2 ) obtained from a quarry, air-dried and characterized. The 474 Montmorillonite clay and humus should be purchased and well characterized. Prior to 475 For some applications, a manufactured soil may be appropriate for preliminary

Draft Version 16

22