Knowra Humus Humus Humus is dark, relatively stable organic material in soil formed as plant and animal remains decompose. It stores nutrients and influences soil structure and water retention.
Decomposition : The breakdown of organic matter into simpler substances by physical, chemical, and biological processes. It begins the transformation of plant and animal remains into humus.
Soil : The natural body at Earth's surface where mineral particles, organic matter, water, air, and organisms interact. Humus exists as part of this layered, living material.
Soil fertility : The capacity of soil to supply nutrients and suitable conditions for plant growth. Humus contributes nutrient reserves and supports biological nutrient cycling.
Fresh organic matter : Recently added plant, animal, or microbial material that has undergone little decomposition. It is less transformed and generally less stable than humus.
Soil microbiology : The study of microorganisms and their activities in soil. Bacteria and fungi drive much of the breakdown and transformation that produces humus.
Plant litter : Dead leaves, stems, roots, and other plant material deposited on or in soil. It is a major input from which humus develops.
Soil structure : The arrangement of soil particles into aggregates and the resulting pore spaces. Organic matter helps bind aggregates and supports a stable structure.
Particulate organic matter : A soil organic matter fraction consisting of recognizable plant and animal residues not strongly bound to minerals. It is generally more recognizable and less mineral-associated than persistent humus.
Lignin : A complex structural polymer in plant cell walls that resists decomposition. Its persistence helps explain why some plant-derived compounds remain in soil longer.
Fungi : A kingdom of organisms that includes yeasts, molds, and mushrooms, many of which decompose organic matter. Fungal enzymes break down tough plant materials that contribute to soil organic matter.
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