RelativeResourceManager(16) - the tillage zone or furrow...

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16 of 17 Example: Convert 4 meq Ca +2 /100 g to ppm. g 1 ug 10 Ca mole 1 Ca g 40 charge mole 2 Ca mole 1 eq 1 charge mole 1 meq 1000 eq 1 soil g 100 meq 4 6 2 2 800 ug Ca +2 /g = 800 ppm Ca +2 in soil We can also use equivalent wt to convert between meq/100 g and ppm. Equivalent wt = valence wt atomic (e.g. Ca +2 : equiv. wt = 2 1 . 40 = 20 g) Solving the same example as above: 2 6 Ca ppm 800 g 1 ug 800 g 1 ug 10 eq 1 g 20 meq 1000 eq 1 g 100 meq 4 Below is a similar example, this time using cmole + /kg as our starting units. Convert 2 cmole + Al +3 /kg to ppm 3 3 3 3 3 Al ppm 180 soil kg Al mg 180 g 1 mg 1000 Al mole 1 g 27 mole 3 Al mole 1 cmole 100 mole 1 soil kg Al cmole 2 Again, this time using equivalent wt: wt Equivalent Al ppm 180 soil kg Al mg 180 g 1 mg 1000 eq 1 g 9 mole 1 eq 1 cmole 100 mole 1 soil kg 1 Al cmole 2 3 3 3 B. Conversion of ppm to lbs./acre. A conversion commonly used when reporting soil test data to farmers is to express concentrations in lbs./acre. This is usually done by assigning a certain depth and weight to
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Unformatted text preview: the tillage zone or furrow slice. Convention has accepted that the furrow slice of an acre weighs 2,000,000 lbs. It can be derived from the following assumptions: Density: Agriculture soils have a bulk density (or dry weight per unit volume) of 1.0 to 1.8 g/cm 3 . Most surface soils are near 1.2 g/cm 3 . Area: An acre is about 207 ft x 207 ft, or 39,805,752 cm 2 or x ha. Volume: If you plow 8 inches deep (20 cm), your acre furrow slice (one acre 8 inches deep) has a volume of 796,115,040 cm 3 . Weight: If you assume a bulk density of 1.2 g/cm 3 , the dry weight of your 796,115,040 cm 3 furrow slice is 955,338,040 grams. Since 1 lb. = 454 grams this equals 2,104,269 lbs., or about 2,000,000 lbs....
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