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CHAPTER 4
Models for Heat
Transfer in Heated
Substrates
Manuel Ramiro Rodriguez and
Maria Dolores Fernandez
Universidad de Santiago de Compostela
Galicia, Spain
4.1 Heat Transfer in Soils
4.1.1 The Soil Thermal Regime
Soil temperature is one of the factors that most influence physical,
chemical, and biological processes in soil and plants. Generally, the
importance of the effects of soil temperature on plants lies in the role
of soil temperature as a controlling factor of the intensity of a series of
processes (Buchan 1991; Jury et al. 1991) that usually reach a maxi-
mum within a given temperature range (Porta et al. 1999).
Temperature affects plant growth and development to such an
extent that plant growth has often been described by a linear approx-
imation dependent on temperature and time (thermal time). This
approach can be used to predict seedling emergence time when soil
temperature is taken into consideration (Finch-Savage et al. 2001).
The dependence between the accuracy of soil temperature estimation
and the prediction of the rate of germination has been studied for
a number of species, such as Geranium carolinium (Washitani 1985),
Pinus densiflora (Washitani and Saeki 1986), chickpeas (Covell et al.
1986; Ellis et al. 1986), lentils, soybeans, and cowpeas (Covell et al. 1986),
millet (García-Huidobro et al. 1982), or soybeans (Andales et al. 2000).
In fact, from among the wide range of factors that affect preemergence
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