ABSTRACT
Temperature has a fundamental control on almost all processes in the environment. In cool climates, it demarcates growing and ‘‘nongrowing’’ seasons. Storage and release of heat in soil control the temperature of both the soil and the lower atmosphere, thus affecting the whole terrestrial biosphere. Yet soil temperature and its effects were traditionally poorly researched, greater attention being given to water, mainly because, with adequate temperature established within the growing season, it becomes the major and often erratic determinant of growth, while being more controllable via irrigation or drainage. More recently, a wider need has arisen to either measure or model the soil temperature regime, defined here to include the depth and time variations of both temperature and heat flux. Thus the literature shows increased attention to effects of soil temperature on soil biological processes, nutrient and fertilizer transformations, physical processes including solute transport, and environmental issues such as soil-atmosphere gas exchanges, the global carbon budget, and the transformations and transport of contaminants. Also, crop growth and evapotranspiration models require improved submodels or measurements of soil temperature regime. Climate modeling and remote sensing require more accurate data, for both heat flow and soil (especially surface) temperature.
