Soil aeration

The S.A.V.E. (soil aeration-vapor extraction) technology combines air stripping, vacuum extraction, and combustion technologies for the remediation of soil, groundwater, and... 

In particular, soil color should be determined on dry and moist samples using Munsell Soil Color Charts (1994). Soil color is usually the first property recorded in a morphological description of soils (and may be the only feature of significance to a layperson) and provides an indicator of redox status because soil color relates to soil aeration and organic matter content (Fitzpatrick, McKenzie, and Maschmedt 1999). Soil color has been found to be extremely useful in forensic soil identification by Sugita and Marumo (1996). 

The presence of salinity in soil and water can affect plant growth in three ways (1) it can increase the osmotic potential and hence decrease water availability (2) it can induce specific-ion effects by increasing the concentration of ions with an inhibitory effect on biological metabolism and (3) it can diminish soil-water permeability and soil aeration by adversely affecting soil structure. The adverse effects of soil salinity on plant growth and productivity varies with the type of plant being grown. 

Whereas diffusion of gas at depth is widespread, mass flow is often localised (near the ground surface, in faults) or intermittent (volcanic emptions). Mass flow is an important consideration in the application of gas geochemistry to mineral because of its significant role in the interchange of atmospheric air and soil air, and therefore its influence on gas composition in the shallow subsurface from where most samples and measurements are taken. Lovell (1979) reviewed soil aeration in this context. 

Source of soil aeration Percentage of total air exchange... 

Tackett, J.L., 1968. Theory application of gas chromatography in soil aeration research. Proc. Soil Sci. Soc. Am., 32 346-50. 

Sheppard, S. C., Sheppard, M. L, and Evenden, W. G. (1990). A novel method used to examine variation in Tc sorption among 34 soils, aerated and anoxic. J. Environ. Qual. 11, 215-233. 

A typical field site, varying in area from about 1 to 10 ha, may include several soil series. The model parameter values may be different not only for each of these soil series, but may also vary considerably within a single series. Such variability in a number of soil hydraulic properties (e.g., soil hydraulic conductivity, soil water flux, etc.) has been widely reported in the literature ( 5 - 1 ). The model parameter values for a given location in the field may also vary with profile depth depending upon soil horizonation as well as a function of the soil and environmental factors (e.g., soil aeration, temperature, etc.). Since soil and environmental factors undergo dynamic changes with time, model parameters are also expected to exhibit temporal variability. At present, only limited data are available to characterize such spatial and temporal variability in pesticide sorption and degradation parameters required in several simulation models. 

Non-capillary pores do not restrict the gravitational action, water is free to move downward and air enters into the emptied spaces. The volume of non-capillary pores is a measure of the soil aeration, i.e. its minimal air capacity (during the saturation of the soil capillaries with water). 

Tolerance to flooding, excess moisture and poor soil aeration. 

In the rice paddies of Japan, according to King, the soil was usually plowed to a depth of 3.5-4.5 inches but in China it was worked deep and often — much of it by hand labor. Apparently extreme efforts were made in China to maintain a soil- or dust-mulch, except, of course, where rice was grown. One can not help but wonder how such a laborious practice could have been followed over the centuries if it is without merit, as has been shown by scientists in recent years. Certainly it has some merit with respect to weed control, mineral availability, and soil aeration, if not for moisture conservation. 

Cultivation has some effect on soil aeration but less than might be expected. Domby and Kohnke (1956), for example, showed that surface crusts on a silt loam restricted gaseous diffusion only at low moisture tensions. The wetter the soil, the greater was the influence of crusts on diffusion. They state that except during a pe lriod of complete sealing, however, crusted soils actually may permit more rapid diffusion and be better aerated than mulched or other uncrusted soils, because of differences in moisture content. ... 

Redox potential that measures electron activity in soils is used as an indicator of soil aeration status in upland environments. Changes in Eh values are small if sufficient oxygen is present in the soil pores. Aerated soils have characteristic Eh values in the range of +300 to +500 mV and air-filled porosity of 0-60% (Figure 6.5). The low concentration of redox couples in aerated soils reduces... 

Field measurements of Eh are significantly correlated with soil oxygen (Figure 6.6), suggesting that Eh measurements can provide a reasonable indication of soil aeration status (Megonigal et al., 1993 Faulkner et al., 1989). Soil Eh and oxygen levels also respond to water table fluctuations in wetlands (Figure 6.7). 

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