Farmers have long recognized the organic matter content of a soil as a key attribute of soil fertility. It seems likely that this awareness, at least in the intuitive sense of recognizing dark-colored, friable, and earthy smelling soils as favorable sites for growing crops, dates back to the beginnings of agriculture. Yet, the history of agriculture is replete with examples of the depletion of organic matter and the subsequent loss of soil fertility through poor management. In part, this has been due to a lack of knowledge about how various agricultural practices affect the soil. However, it also reflects an inherent conflict between maximizing short-term production at minimal cost vs. providing for the sustained health and long-term productivity of the soil. This tradeoff, between short-term production goals and long-term investment in maintaining soil fertility, characterizes much of the history of agriculture. The development 16of agriculture in temperate regions has exhibited recurrent patterns of exploitative soil use followed by the introduction of regenerative practices as soil resources fell to unacceptable levels. In some cases, severe degradation of the soil led to the collapse of societies and a permanent or long-term loss of productive lands.