Тупроқшунослик асослари

ТУПРОҚШУНОСЛИК АСОСЛАРИ
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2.
Titrate two blank samples (no soil) before proceeding with any unknown samples in order 
to standardize the Ferrous Sulfate solution. If the difference between the two blanks is not 
within 0.2 mL of Ferrous Sulfate solution, clean the burette and associated tubing. 
Reanalyze two more blanks to determine if the problem has been eliminated. 
3.
Pipet 10.0 mL of the Potassium dichromate solution into each flask containing unknown 
soil and mix by carefully rotating the flask to wet all of the soil. 
4.
Under a fume hood, carefully add 20 mL of concentrated Sulfuric Acid to each flask and 
mix gently. 
5.
Allow flasks to stand for 5 min under the fume hood.
6.
Add pure water to each flask such that the final volume is approximately 125-mL. Mix by 
swirling gently.
7.
Allow the samples to cool and return to room temperature and recheck volume after 30 
minutes. 
8.
Add 5 or 6 drops of Phenanthroline complex and immediately titrate with the Ferrous 
Sulfate solution. Use a mixing bar to properly mix the sample as it is titrated. As the 
titration proceeds, the solution will take on a green color that will change abruptly to 
reddish-brown when the endpoint of the titration is reached.
9.
Record each volumetric reading to the nearest X.X mL. 
Calculation (
натижаларни хисобалаш
) 
(1 - S / B) x 10 x 0.68 = organic matter (%) of sample 
S = Volume of Ferrous Sulfate solution required to titrate the sample, in mL. 
B = Average Volume of Ferrous Sulfate solution required to titrate the two blanks, in mL. 
10 = conversion factor for units. 
0.68 = a factor derived from the conversion of % organic carbon to % organic matter
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Савол ва топшириқлар: 
1.
Гумус деганда қандай модда тушунилади? 
2.
Тупроқ гумусини аниқлашнинг яна қандай усуллари бор? 
3.
Гумус таркибида углерод неча фоизни ташкил этади?