Humic acid is extracted from natural weathered coal, and it is a permanent humic substance and cannot be degraded that fast by the microorganism in the soil. 

Powder form are always used as raw material to produce humic acid compound fertilizer.

Humic acid is extracted from natural weathered coal, and it is a permanent humic substance and cannot be degraded that fast by the microorganism in the soil. 

Granule form can be directly used to improve soil.