Soil temperature

Once in the soil solution, urea—formaldehyde reaction products are converted to plant available nitrogen through either microbial decomposition or hydrolysis. Microbial decomposition is the primary mechanism. The carbon in the methylene urea polymers is the site of microbial activity. Environmental factors that affect soil microbial activity also affect the nitrogen availabiUty of UF products. These factors include soil temperature, moisture, pH, and aeration or oxygen availabiUty. 

Soil Temperature. In temperate climates, NO and NjO emission rates increase with increasing soil temperature and a response to diurnal and seasonal temperature variations has been reported freqnently." Activation energies for both soil NO and NjO emissions are usually in the range of 30-150 kJ mol ... 

For this particular data set, the dependence of NjO emissions on soil temperature changes was not as conclusive as for NO. 

NO Soil nitrogen, soil temperature, soil water (soil physical properties) approximately empirical... 

Williams et alN produced an inventory of soil NO emissions for the United States based on land use category and soil temperature variations, and estimated that on an annual basis the soil source was only 6% of the man-made NO, source. 

How would the release of a volatile gas from contaminated soil be affected by the soil temperature ... 

The resistivity of the soil in any particular location will be a function of moisture content, soil temperature and presence of dissolved salts. At a site where climatic conditions vary considerably throughout the year, earth electrodes should be buried at a depth where such changes will not affect the resistivity. Grounding rods are generally made of copper bonded onto a steel core. The copper provides a good connection to earth and offers a high corrosion resistance, while the steel core gives the mechanical... 

The maximum temperature and duration of heating during fires are important variables that influence the soil nutrient status, as well as the survival of residual vegetation following fire (Table III). Deforestation results in the presence of large quantities of wood debris in close proximity to the soil surface. Fires in this scenario result in soil temperatures and magnitudes of heat flux far in excess of those which occur in fires in uncut forests (Shea, R. W. Oregon State University, unpublished data). 

Loss of nitrogen compounds from soils is also a major pathway into the atmosphere for some compounds (e.g., N2O, NO, and NH3). As in the aquatic systems, parameters that play an important role in this process include the nature of the compound soil temperature, water content, pH, aeration of the soil and a concentration gradient of the gas in question. 

Fig. 2.3 Grass growing days per year (soil temperature adjusted for drought factor and altitude) (Lazenby Doyle, 1981).

Thermal enhancement of volatilization.19 21 Volatility of contaminants increases greatly with temperature, so several techniques have been developed to raise soil temperature, including the injection of hot air or steam, electrical resistance heating, and radio frequency heating. 

Performance data Percolation is being measured with a lysimeter connected to flow monitoring systems, soil moisture is being measured with water content reflectometers, and soil matric potential and soil temperature are being monitored with heat dissipation units. From November 1999 to July 2002, the capillary barrier cover system had a cumulative percolation of 0.5 mm. Total precipitation was 837 mm over the 32-month period. Additional field data were collected through 2005. 

RI = radiation intensity RH = relative humidity RT = relative temperature SH = soil moisture ST = soil temperature. Mean and range for each variable. Means followed by different letters (a, b) within the same column indicate statistically significant differences (P <0.05). 

Soil temperature (ST) is one of the most stable variables, although differences can be detected considering 100% at the edge (18°C on average) is reduced to 25% in the interior. 

Wang B, Neue HU, Samonte HP. The effect of controlled soil temperature on diel CH4 emission variation. Chemosphere. 1997 35 2083-2092. 

The soil temperature was created based on air temperature and the data are presented in the Fig. 11. 

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