Agriculture Reference
In-Depth Information
microbes on SOM can also determine the rate of green house gas emission.
Soil microbes are able to mineralize soil organic matter, resulting in the
production of CO 2 and other greenhouse gases as well as the release of
available nutrients. Therefore, the rate of microbial activity and population is
also a determining factor in the emission of greenhouse gases (Widmer et al.,
2006).
Climate, soil tillage, plant species and soil properties are also among the
parameters affecting the production of greenhouse gases. With increasing
moisture and temperature the rate of SOM mineralization also increases (Fang
et al., 2005a). Soil tillage increases the flux of O 2 into the soil resulting in the
enhancement of SOM mineralization. Accordingly, use of no- or reduced
tillage is superior to the use of conventional tillage decreasing the rate of
greenhouse gases (Puget and Lal, 2005; Leifeld and Kogel-Knabner, 2005).
SOM is able to keep higher rate of water in soil as it can behave like a sponge.
Hence, in a soil with higher rate of organic matter there is more available
water for the use of plants and microbes.
Plant species are also effective on the emission of greenhouse gases
through the activity of their roots and the biochemical combination of their
tissues. Higher soil respiration results in the higher production of greenhouse
gases. The biochemical compounds of SOM determine its color. The main
element in the compounds is carbon (C) resulting in a dark color affecting soil
color. Soil color can affect many physical, chemical and biological properties
of soil (Kögel-Knabner, 2002). A dark soil is able to absorb higher rate of sun
energy because of a higher heat capacity increasing its temperature and
affecting soil micro climates. A warmer soil is more suitable for seed
germination and microbial activities. It can also affect the amounts of water
evaporated from the soil surface.
SOM is a source with high amounts of nutrients. It is because there are
nutrients in the structure of organic tissues and/or each functional group
forming the structure of SOM contain high rate of nutrients as they have
electron charges absorbing nutrients. SOM are mineralized by soil microbes
turning into mineral nutrients and the humic part, which is highly resistant to
microbial decomposition. In other words soil microbial activities recycle the
nutrients in the structure of organic matter (Kögel-Knabner, 2002).
As previously mentioned there are electron charges on the edges of each
functional group, absorbing different nutrients. The available charges are
resulted by the structural properties of each functional group or pH fluctuation
of the soil environment. The ability of soil particles and SOM for the exchange
of nutrients with the surrounding solution is called cation exchange capacity
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