Michigan State University
Michigan State University: Digital Learning Center for Microbial Ecology: Microbe Zoo: Ag Acres
A simple overview of the important roles microbes play in agriculture. You'll learn how some microbes can be hazardous to plants while others help fertilize and build soil, and kill insects.
Other
What Is a Soil Test?
The North Carolina Department of Agriculture explains soil testing, taking a soil sample, and analyzing the results.