Down To Earth Granular Humic Acid 50 lbDown To Earth Granular Humic Acids 50lb OMRI Listed A highly concentrated source of Humic acids ideal for use on fields, turf and vegetable gardens. Derived from the ancient remains of decomposed organic plant materials, Humic acids enhance nutrient uptake and stimulate soil microbial life. Naturally occurring, unaltered oxidized lignite containing 70% total Humic and fulvic acids, crushed, screened and graded to a particle size of 1 3 mm. OMRI Listed.