Author
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Sojka, Robert |
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SCOTT, H - UNIVERSITY OF ARKANSAS |
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Submitted to: Encyclopedia of Soil Science
Publication Type: Book / Chapter Publication Acceptance Date: 4/1/2001 Publication Date: 9/1/2002 Citation: N/A Interpretive Summary: Soil aeration refers to the ability of soil to provide oxygen to the living organisms in soil, including microorganisms, roots of higher plants, and meso- and macro-fauna such as insects, worms, or burrowing reptiles or mammals. The oxygen status also determines the pathway of many common chemical reactions in soil, influencing the balance of certain nutrient ions, fate of nitrogen, and production of toxic chemicals from certain minerals when they are chemically reduced, or from biochemical bi-products of non-aerobic respiration. Quantifying the status of soil aeration is challenging because there are several conceptual approaches that can be taken to express the adequacy of aeration. Measurement of the gas-filled pore space in soil (a capacity factor) is relatively simple to accomplish, but gives no insight to the proportion of gas that is oxygen. The concentration of oxygen or other gases (an intensity factor) is more difficult to measure, but adds insight about the size of the oxygen supply, yet it still tells nothing about whether the oxygen can meet the demand of living organisms and non-biotic oxidation processes of soil. Measuring a soil's ability to supply oxygen (a rate factor) gives the best characterization of soil aeration because it can be related to directly biotic response, regardless of other soil mineral and physical properties. This chapter discusses the various methods of obtaining capacity, intensity and rate factors to characterize soil aeration. Particular detail is presented regarding some of the newest techniques for measuring oxygen diffusion rates in soil. Technical Abstract: Soil aeration refers to the ability of soil to provide oxygen to the living organisms in soil, including microorganisms, roots of higher plants, and meso- and macro-fauna such as insects, worms, or burrowing reptiles or mammals. The oxygen status also determines the pathway of many common chemical reactions in soil, influencing the balance of certain nutrient ions, fate of nitrogen, and production of toxic chemicals from certain minerals when they are chemically reduced, or from biochemical bi-products of non-aerobic respiration. Quantifying the status of soil aeration is challenging because there are several conceptual approaches that can be taken to express the adequacy of aeration. Measurement of the gas-filled pore space in soil (a capacity factor) is relatively simple to accomplish, but gives no insight to the proportion of gas that is oxygen. The concentration of oxygen or other gases (an intensity factor) is more difficult to measure, but adds insight about the size of the oxygen supply, yet it still tells nothing about whether the oxygen can meet the demand of living organisms and non-biotic oxidation processes of soil. Measuring a soil's ability to supply oxygen (a rate factor) gives the best characterization of soil aeration because it can be related to directly biotic response, regardless of other soil mineral and physical properties. This chapter discusses the various methods of obtaining capacity, intensity and rate factors to characterize soil aeration. Particular detail is presented regarding some of the newest techniques for measuring oxygen diffusion rates in soil. |
