Biological characteristics
Soil has a wide range of species. Bacteria, fungi, protozoans, and nematodes are the dominant organisms. The habitat of soil creatures includes gaps within a surface litter, cavities in soil aggregates, pore spaces inside individual soil particles, and root canals. These organisms get their food from living plants’ roots and organic substances found in the pore spaces. Mites are the most prevalent animals in the soil. The earthworms are a part of the wider fauna. Millipedes that feed on the litter’s surface break it down mechanically, making it more susceptible to fungus-induced decomposition. Millipedes eat mushrooms in the trash to survive. Along with millipedes, snails and slugs aid in the hydrolysis of lignins and even very indigestible cellulose. The breakdown of the cellulose in wood is caused by bigger occupants like termites and some dipterans. The fauna of tropical soil is dominated by termites.
The development of O and A layers is significantly influenced by soil organic matter, which results from biological processes during decomposition. Humus, a dark-coloured, chemically complex organic compound with distinctive components like fulvic acid and humic acid, is the portion of organic matter that survives after decomposition. Physical, chemical, and biological forces interact to generate two different forms of humus;
Mor: The organic layer is dense and clearly defined, sitting on mineral soil. Horizons O and A are distinct from one another. The primary decomposition organisms are fungi, which also create acid and reduce soil animal activity.
Mull: The mineral soil has a high level of organic content, and there is only a small covering of litter on the surface. There is a lot of animal activity. The O and A horizons don’t abruptly diverge. In this soil, bacteria are the primary decomposers.