Soil organic matter and soil organisms

Soil biomass (living organic matter) = living plants and animals and micro-organisms.

Humus the slowly decomposing residue of soil organic matter chiefly fibrous vegetation, decomposed gradually by active micro-organisms into a black, colloidal material that coats soil particles. it has a high CEC.

Organic matter levels in the soil depend on how much fresh material is added, compared with the rate of decomposition. It is stable when these two processes are balanced. This is determined by climate soil type and cultivation Most topsoil contains between 1- 6% of organic matter, subsoil contains less than 2%.

Soil composition

macro-organisms- ( small animals and predators) insects, ants, beetles, mites and spiders

macro-organisms- (herbivores and detrivores ) rabbits mice springtails ants beetles grubs woodlice earthworms slugs millipedes snails

Micro-organisms detrivores, predators or parasites detrivores, predators or parasites (nematodes, protozoa and rotifers) Soil flora Soil flora (growing things) include Roots of higher plants, algae, fungi (mushrooms, yeasts and moulds), actinomycetes and various bacteria

Earthworms – 10 common species responsible for refining dead plant remains (their main food source) and other organic matter. active when conditions are favourable: adequate moisture pH 6-7 soil temperature (around 10ºC) Slugs, snails, arthropods (such as millipedes, springtails, and mites and nematodes) play an important part in the decomposition of organic matter.

Bacteria single celled organisms existing in clumps or colonies. Most are heterotrophic, getting their energy from the carbon in organic matter; they are present in soils in large numbers and play a major part in the decomposition of organic matter, minerals and other substances.