Biological functions of humic acid substances
The activity of soil organisms and microorganisms has a significant impact on soil fertility, and HS can provide the main energy source for soil organisms and microorganisms. Help build populations and promote beneficial activities, including enabling soil microbes and their metabolites to adsorb and convert toxic metals or organic elements and reduce their toxicity. Soil-living bacteria, actinomyces, fungi, algae, protozoa, nematodes and even some large organisms, such as earthworms, are associated with the content and conversion of organic matter or HS.
A large number of experiments have shown that the application of HA can significantly promote microbial community activity and improve enzyme activity. At the same time, studies have proved that both HA and FA can significantly promote the growth of azotobacter and improve its nitrogen fixation ability, and FA has a greater role. The experiment applied HA to upland soil for four consecutive years and found that soil microbial carbon, nitrogen, and phosphorus contents increased year by year, and soil sucrase, urease, and catalase activities also increased year by year. It was also found that soil enzyme activity had a good correlation with soil microbial biomass.
HA can promote the growth of azotobacter, Bacillus, Aspergillus niger and Penicillium griseus, etc. Some Pseudomonas and Sulfur-Ferribacter can oxidize Cu, Mn, As, Fe, etc., and some Bacillus, Penicillium and sulfur-reducing bacteria can reduce toxic Cr6+ and Hg2+ and precipitate water-soluble Cd salts, all of which are conducive to reducing the toxicity of toxic substances and are of great significance for agricultural ecological construction.