Humic acid is a condensed, refractive mixture of aromatic organic acids. It is complex and variable and has not been characterized (as far as i know) to any degree (except perhaps for some of the many functional groups). Humic acid contains sulfur, nitrogen and phosphorus in varying amounts. It also contains metals such as ca, mg, cu, zn etc. Which can be 'chelated' in some undefined way. Humic acid can be broken down into two groups based on the polarity and size of the individual compounds'. The smaller, more polar fraction is generally termed fulvic acid and the larger, more nonpolar fraction is generally termed humic acid. Humic acids are the endproduct of microbial degradation of plant and animal debris and are one of the most important constituents of fertile soils. 25kg/50kg net bag