are humic and fulvic acids
of natural origin, which are found in soil, peat, sapropel, as well as in lignite, silt and lignin.
Humic substances have a positive effect on plant growth and development - they stimulate seed germination, increase the length and biomass of seedlings, reduce the penetration of heavy metals and radionuclides into plants. This effect is particularly noticeable in the early stages of plant development, but in some cases it is manifested during the whole ontogenesis, including the yield of products.
The strongest effect of humic substances is manifested under unfavorable environmental conditions:
- insufficient or excessive soil moisture;
- low temperatures;
- insufficient illumination;
- soil contamination with heavy metals, radionuclides or organic pollutants.