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The word oxygen in the literature typically refers to the most common oxygen allotrope, elemental/diatomic oxygen (O 2), as it is a common product or reactant of many biogeochemical redox reactions within the cycle. [2] Processes within the oxygen cycle are considered to be biological or geological and are evaluated as either a source (O 2 ...
Water is a critical agent in soil development due to its involvement in the dissolution, precipitation, erosion, transport, and deposition of the materials of which a soil is composed. [39] The mixture of water and dissolved or suspended materials that occupy the soil pore space is called the soil solution. Since soil water is never pure water ...
The spaces between the solid soil particles, if they do not contain water, are filled with air. The primary soil gases are nitrogen, carbon dioxide and oxygen. [2] Oxygen is critical because it allows for respiration of both plant roots and soil organisms. Other natural soil gases include nitric oxide, nitrous oxide, methane, and ammonia. [3]
The specific heat of pure water is ~ 1 calorie per gram, the specific heat of dry soil is ~ 0.2 calories per gram, hence, the specific heat of wet soil is ~ 0.2 to 1 calories per gram (0.8 to 4.2 kJ per kilogram). [90] Also, a tremendous energy (~584 cal/g or 2442 kJ/kg at 25 °C) is required to evaporate water (known as the heat of ...
The water content of most vegetal detritus ranges from 60% to 90%. The dry matter consists mainly of carbon, oxygen, and hydrogen. Although these three elements make up about 92% of the dry weight of the organic matter in the soil, other elements present are essential for the nutrition of plants, including nitrogen, phosphorus, potassium ...
The majority of these organisms are aerobic, so the amount of porous space, pore-size distribution, surface area, and oxygen levels are crucial to their life cycles and activities. The smallest creatures (microbes) use the micropores filled with air to grow, whereas other bigger animals require bigger spaces, macropores , or the water film ...
The tricarboxylic acid (TCA) cycle – or citric acid cycle – is an important step in cellular respiration. In the TCA cycle, a six carbon sugar is oxidized. [1] This oxidation produces the CO 2 and H 2 O from the sugar. Plants, fungi, animals and bacteria all use this cycle to convert organic compounds to energy.
Thus, percolating water stimulates weathering reactions and helps differentiate soil horizons. Likewise, a deficiency of water is a major factor in determining the characteristics of soils of dry regions. Soluble salts are not leached from these soils, and in some cases they build up to levels that curtail plant [49] and microbial growth. [50]