Helinä Hartikainen

Elämästä humusta - humuksesta elämää

Hartikainen H. Elämästä humusta - humuksesta elämää.

Tiivistelmä

Despite agreement that organic matter is an essential soil component, terminological confusion may result in inexact concepts of its role in controlling the chemical, physical and biological processes. Humus, which is synthesized primarily in humification process by microbes, is structurally very complex and resistant to degradation. It is produced from non-humus material: litter, a whole series of decomposition products, and identifiable constituents. Classifying soil organic matter into humus and non-humus materials permits the systematization of reactions involving organic matter. Microbial degradation of non-humus material releases plant nutrients and produces polysaccharides that stabilize soil aggregates, thus improving conditions for root growth. Antibiotics, vitamins and other active compounds affecting the biotic system can end up into soil as byproducts of the microbial metabolism. Only a very small portion of non-humus material is used as raw material for humus, whose importance is based on physico-chemical properties. Through its high water holding capacity, humus can physically control the mobility of compounds. Diverse functional groups participate in various types of chemical reactions (ion exchange, complex formation, dissolution, physical sorption of non-polar organic chemicals, etc). Similarly as in soil, humus acts as a buffer in water bodies. However, in contrast to soil, in waters photochemical reactions can enhance its degradation, thus leading to nutrient loadings and oxygen budget problems.

Avainsanat
buffering; degradation; fulvic acids; humic acids

Vastaanotettu 31.10.2017 Julkaistu 1.1.2003

Katselukerrat 1191

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