A comprehensive look at science behind the role of carbon in plant-soil systems, and a review of the efficacy of carbon-based products (humic acid, fulvic acid, biosolids, manure, compost, biochar, etc.) This presentation teaches which Carbon-based substance are valuable in plant-soil systems, and which aren’t, so that anyone can quickly sort through the myriad of carbon-based products in the market and find the ones of most value to them.