Author
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Sojka, Robert |
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Submitted to: Yearbook of Science and Technology
Publication Type: Book / Chapter Publication Acceptance Date: 4/15/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Adequate soil oxygen availability is essential to the growth of higher plants, especially the food and fiber crops grown in agriculture. Soil oxygen availability can be characterized as a capacity factor (volume of soil air), an intensity factor (concentration of oxygen in soil air), or a rate factor (rate of oxygen diffusion to an oxygen sink in the soil matrix). Soil oxygen diffusion rate (ODR) is characterized using a platinum micro-electrode to simulate the oxygen reduction at a root tip. Oxygen diffusion to a respiring soil organism depends on the tortuosity of the diffusion path through soil, the thickness of water films around the organism, and the concentration gradient along the diffusional pathway. Soil water content is especially important, because oxygen diffuses 1/10,000 as fast through water as air. Adequacy of soil ODR requires a balance between rate of oxygen supply and respiratory demand. Respiration approximately doubles with each 10 degrees Centigrade temperature increase. Aerobic and anaerobic sites exist simultaneously in most soils because of respiration at the center of soil aggregates. Plant responses to soil oxygen are increasingly recognized as factors that impact on plant processes affecting yield, and suitability to oxygen limiting soil conditions. |
