The Impact of Humic Acid on Soil Microbial Community Structure
It is well known that the role of soil microorganisms in forming soil structure, mineral matter decomposition, nutrient cycling, and plant growth promotion cannot be ignored. Soil microbial biomass is the driving force behind the soil nutrient cycling and material transformation processes, and is also an important source of active soil nutrients and plant-available nutrients in the soil.
As the most active and changeable part of soil organic matter, soil microbial biomass can sensitively, promptly, and accurately reflect changes in soil fertility and soil health, and is one of the important indicators for evaluating soil quality. Humic acid, as an important substrate for microorganisms, can provide an organic acid environment and create a good living environment for microorganisms.
At the same time, humic acid also contains a large number of minerals, amino acids, and other nutrients, which can promote the growth of soil microorganisms and greatly enhance soil microbial activity, providing environmental protection for plant roots to absorb soil nutrients.
Of course, the amount of humic acid added has a great impact on the soil microbe community. Studies have found that appropriate concentration of humic acid treatment significantly improves soil bacterial species diversity and changes the fungal community structure, reflected in the increase in the relative abundance of Actinomycetes, Aerobic Bacteria, Silicate Bacteria, Fibrolytic Bacteria, Azotobacter, and so on.
With the increase in humic acid amount (0 to 180 kg/hm2), the number of Actinomycetes in soil significantly increased, and the changes in the number of bacteria and fungi were not significant. Another study found that a humic acid amount of 450 kg/hm2 can significantly increase the number of bacteria and fungi in soil for planting cucumbers, and the number of Actinomycetes also increases with the increase in humic acid amount.