Paragraph 8 EXPRESSION OF RESULTS

If the quantities and the dilutions shown in the Table are used, the following formulae apply:

• or

  $$\mathrm{\%}\mathrm{K}\mathrm{in}\mathrm{the}\mathrm{fertiliser}=\left(\mathrm{A}-\mathrm{a}\right)\times \mathrm{f\text{'}}$$

  where:

  • A = mass in grams of the precipitate from the sample

  • a = mass in grams of the precipitate from the blank

  • f and f' = factors — see Table.

• With samples and dilutions which differ from those of the Table use the following formulae:

  $$\mathrm{\%}\mathrm{K}2\mathrm{O}=\genfrac{}{}{0.1ex}{}{\left(\mathrm{A}-\mathrm{a}\right)\times \mathrm{F}\times \mathrm{D}\times 100}{\mathrm{M}}$$

• or

  $$\mathrm{\%}\mathrm{K}=\genfrac{}{}{0.1ex}{}{\left(\mathrm{A}-\mathrm{a}\right)\times \mathrm{F\text{'}}\times \mathrm{D}\times 100}{\mathrm{M}}$$

  where:

  • F = conversion factor, KTPB into K₂O = 0.1314

  • F' = conversion factor, KTPB into K = 0.109

  • D = dilution factor

  • M = mass in grams of the sample for analysis.

  TABLE FOR METHOD 11

  % of K2O in the fertiliser	% of K in the fertiliser	Sample for analysis (g)	Aliquot portion to be taken as a sample for precipitation (ml)	Conversion factor f % K2O g KTPB	Conversion factor f' % K g KTPB
  1-5	0.8-4.2	20	50	13.14	10.91
  5-10	4.2-8.3	10	50	26.28	21.81
  10-20	8.3-16.6	10	25	52.56	43.62
  20-50	16.6-41.5	10	10	131.40	109.10
  more than 50	more than 41.5	5	10	262.80	218.10