ABSTRACT
Soils are open systems. They are not isolated from the rest of the world. Matter and energy are exchanged between soils and surrounding environments. Soils are always changing in response to their changing surroundings. Fluctuations in soil heat and water were discussed in Chapters 4 and 5. The water cycle will be revisited and mass transfers will be discussed on a global scale in this chapter. Mass transfers are discussed both as total mass and as individual chemical elements.
