SPADA Docs

For some applications, a manufactured soil may be appropriate for preliminary 477 studies. However, a manufactured soil is not recommended for full testing as it does not 478 recapitulate all of the properties of real soil. Manufactured soils are prepared using 479 defined recipes. As such, they do not include soil organisms that are an essential part of 480 the soil. Microorganisms impact nutrient cycling, soil structure, water retention and other 481 processes that naturally occur in soil. The manufactured soil recipes provided here use 482 only 1 clay mineral. There are over 2,000 known minerals with 20 major minerals that 483 can be found in soil. 484 All materials that will be used to prepare manufactured soil should be pretreated as 485 follows. Wash in dish detergent and tap water; thoroughly rinse with hot tap water to 486 remove soap; rinse four times with ASTM-compliant Type 2 purified water (>5 MΩ 487 cm@25ºC; TOC <30 ppb ); and rinse three times with ASTM-compliant Type 1 purified 488 water (18 MΩ cm@25ºC; TOC <10 ppb). Additionally, all glassware and plasticware 489 should be rinsed with 0.1 N nitric acid after the Type 2 water rinses and prior to the Type 490 1 water rinses. 491 It is recommended that two manufactured soils be prepared consisting of sand and 492 montmorillonite clay with and without humus. The sand component should be purified 493 silica sand (SiO 2 ) obtained from a quarry, air-dried and characterized. The 494 Montmorillonite clay and humus should be purchased and well characterized. Prior to 495 use, the humus should be air-dried, passed through a sieve (≤5 mm), milled in a soil 496 grinder, then passed through a second sieve (≤2 mm). 497 Prepare the two soil mixtures as follows. All masses are oven-dry masses. The 498 textural class of both soil mixtures is expected to be Loamy Sand (15). 499

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