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Bacteria and Archaea, the smallest organisms in soil apart from viruses, are prokaryotic. They are the most abundant microorganisms in the soil, and serve many important purposes, including nitrogen fixation. [9] Some bacteria can colonize minerals in the soil and help influence weathering and the breaking down of these minerals.
Soil life, soil biota, soil fauna, or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil-litter interface. These organisms include earthworms, nematodes, protozoa, fungi, bacteria, different arthropods, as well as some reptiles (such as snakes ...
They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it available to plants. Many organisms enhance soil aggregation and porosity, thus increasing infiltration and reducing surface runoff. Soil organisms prey on crop pests and are food for above-ground animals.
Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rocks into soil for plants. [11] Since some uninhabited land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria, and leaves that employ transpiration.
The effect of biological soil crusts on water infiltration and soil moisture depends on the dominant crust organisms, soil characteristics, and climate. In areas where biological soil crusts produce rough surface microtopography, water is detained longer on the soil surface and this increases water infiltration.
Soil salinity can vary between extremes in a relatively small area; [27] this allows plants to seek areas with less salinity. It is hard to determine which plants can grow in soil with high salinity because the soil salinity is not uniform, even in small areas. [27] However, plants absorb nutrients from areas with lower salinity. [27]
At the supermarket, this variety is sold in plastic boxes or bags (vs. loose) and typically labeled "washed" or "triple washed," according to Trout. RTE spinach does not need to be washed, she says.
In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer. Not all plant cells grow to the same length. When cells on one side of a stem grow longer and faster than cells on the other side, the stem bends to the side of the slower growing cells as a result.