Estimation of Humus in Soil / Manure
Take 20 g soil or manure in a conical flask and add 100 mL of extractant ( 1 : 5 ratio ) .
Shake well and allow standing for 18 h .
Filter through Whatman filter paper no . 1 ( the residue portion on filter paper is called humin and the filtrate is humus .
It is dark brown in color with pH 13 ) .
To get rid of sodium , the humus is dialyzed in dialysis tubes or parchment paper against running tap water for 24 h .
It is free of sodium .
Measure the volume , and a known volume ( 10 mL ) is taken in a pre - weighed 100 mL beaker .
The beaker is dried in an oven at 70°C to a constant weight .
The difference in weight gives the amount of humus in 10 mL .
Accordingly , it is calculated on a percentage basis .
