Range of fluctuation more narrower in the subsurface. Variations are diurnal and seasonal. Microbes vary widely in regard to ability to initiate growth over certain range of temperature. Cardinal temperatures for given organism or microbial process can be defined General shape of temperature response curve similar for most organisms. Most soil organisms are adapted to survival over wide range of temperature and can survive low temps.
Soil acidity is natural or comes from acid rain, heavy use of fertilizers.
At charged surfaces may be much more acidic than adjacent solution. Processes such as decomposition of high nitrogen organic matter may result in high pH microsites. Though sorption usually reduces availability at the microscale, on a larger scale may permit retention of nutrients in system from which they would otherwise leach out. This makes it difficult to extract them from soil. Even if organic matter content high, may not be available.