RelativeResourceManager(11) - (acre furrow/slice) of soil...

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11 of 17 To convert this to meq Ca 2+ /100 g soil: Ca mmole ) ( meq 2 Ca mg 40.1 Ca mmole 1 Ca μ g 1000 Ca mg 1 soil g 1 Ca μ g 4000 2 = soil g Ca meq 0.199 2 = soil g 100 Ca meq 19.9 2 (molecular weight of Ca is 40.1. Charge is +2, so 2 equiv/mole or 2 meq/mmole) To convert this to cmol (+) /kg soil: soil kg 1 soil g 1000 Ca cmole 1 cmole 2 Ca mmole 10 Ca cmole 1 Ca mg 40.1 Ca mmole 1 Ca μ g 1000 Ca mg 1 soil g 1 Ca μ g 4000 ) ( 2 = soil kg cmol 19.9 ) ( Usually in the analysis of soils, an extract of soil is analyzed in ppm (μg /ml) of the element of interest. In order to complete the actual concentration of the element in the soil, two steps must be taken: 1. Calculation of a dilution factor to convert ppm in the extract to ppm in the soil. 2. Conversion of ppm in the soil to meq/100 g soil or cmol (+) /kg soil. Note: 1. The elements Ca, Mg, K, and Na are expressed as meq/100 g soil and P, S, and the micronutrients are expressed as ppm. 2. Conversion of ppm or meq/100 g to lbs./acre relies on the assumption that an acre 6"
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Unformatted text preview: (acre furrow/slice) of soil weighs 2 x 10 6 lbs. Examples of Dilutions 25 g of soil is extracted with 100 ml of ammonium acetate (1:4 dilution). The extract is then diluted twice , each time diluting 10 ml to 100 ml with water (1:10 dilution). Analysis of the final dilution yields 6 ppm Ca. Calculate: ppm Ca in soil; meq Ca/100 g soil; and lbs./acre Ca. ml 10 ml 100 ml 10 ml 100 soil g 25 ml 100 ml μ g 6 = soil g μ g 2400 Ca or 2400 ppm of Ca in soil. Therefore, the dilution factor to convert ppm in the extract to ppm in the soil is 400. This completes step one. Next convert to meq/100 g soil. mmole meq 2 mg 40.1 mmole 1 μ g 1000 mg 1 soil g Ca μ g 2400 2 = soil g Ca meq 0.199 or soil g 100 Ca meq .9 1 1 Note: Molecular weight of Ca is 40.1 and charge is 2+ (so equivalent weight of Ca is 40.1/2 = 20)....
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This note was uploaded on 06/21/2011 for the course NRES 201 taught by Professor Olson,k during the Spring '08 term at University of Illinois, Urbana Champaign.

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