A study of 82 sites in 21 counties by Iowa State University showed that in the 50 years from 1959, soil structure and levels of organic matter had degraded while acidity had increased.

These are important processes that govern microbial community structure, soil mineralogy, soil solution chemistry , and pollutant fate and transport (Lovley 1995, Sparks 2003). where σ is the ...

which leads to improved soil structure and promotes a healthy, fertile soil; by using green manure or growing legumes to fix nitrogen from the air through the process of biological nitrogen fixation; ...