Credits: 3Microbial species of agricultural soils, environmental factors affecting their numbers and activity, and biochemical changes brought about by these organisms. Laboratory course to accompany PS 421 Prerequisites: BIOL 151-151L and BIOL 153-153L or BOT 201-201L. Corequisites: PS 421L-421/521L-521. Cross-Listed: MICR 421-421L/521-521L.