From: Separation of acid-soluble constituents of soil humic acids by dissolution in alkaline urea solution and precipitation with acid
Humic acid
Asha (g kg−1)
Elemental compositionb (g kg−1)
C
H
N
S
O
Fujisaki
9.6
530
51.7
56.2
7.4
355
Dando
6.7
52.5
44.9
2.9
369
Takizawa
568
41.0
39.5
2.5
349