and that there were "relatively large responses at low application rates". A 1998 study by scientists at the North Carolina State University College of Agriculture and Life Sciences showed that addition of humate to soil significantly increased root mass in creeping bentgrass turf. A 2018 study by scientists at the University of Alberta showed that humic acids can reduce prion infectivity in laboratory experiments, but that this effect may be uncertain in the environment due to minerals in the soil that buffer the effect. Anthropogenic production Humans can affect the production of humic substances via a variety of ways: by making use of natural processes by composting lignin or adding biochar (see soil rehabilitation), or by industrial synthesis of artificial humic substances from organic feedstocks directly. These artificial substances may be similarly divided into artificial humic acid (A-HA) and artificial fulvic acid (A-FA). Lignosulfonate from sulfite pulping can be made to mimic humus by hydrolysis and oxidation. The product is already commercialized as "lignohumate". Agricultural litter can be turned into an artificial humic substance by a hydrothermal reaction. The resulting mixture can increase the content of dissolved organic matter and total organic carbon in soil. Lignite (brown coal) may also be oxidized to produce humic substances, reversing the process of coal formation. This form of "mineral-derived fulvic acid" is widely used in China. This process also occurs in nature, producing leonardite. Economic geology In economic geology, the term humate refers to geological materials, such as weathered coal beds (leonardite), mudrock, or pore material in sandstones, that are rich in humic acids. Humate has been mined from the Fruitland Formation of New Mexico for use as a soil amendment since the 1970s, with nearly 60,000 metric tons produced by 2016. Humate deposits may also play an important role in the genesis of uranium ore bodies. Technological applications The heavy-metal binding abilities of humic acids have been exploited to develop remediation technologies for removing heavy metals from waste water. To this end, Yurishcheva et al. coated magnetic nanoparticles with humic acids. After capturing lead ions, the nanoparticles can then be captured using a magnet. Ancient masonry Archeology finds that ancient Egypt used mudbricks reinforced with straw and humic acids. See also Humus Soil Humin Polycyclic aromatic hydrocarbon References External links Supramolecular Humic Systems in the Environment (In English, original is Italian) Further reading Sillanpää, M. (Ed.) Natural Organic Matter in Water, Characterization