Version 2.0, Summer 2022

• Numerous links added to interesting and helpful material.  Most of these are listed at the end of chapters.
• All chapters: minor rewordings and some paragraphs of information added
• Chapter 22: added figures on the nitrogen cycle
• Chapter 28: section on Brassica crops added
• A Sampling of Inanimate Life: rewritten and expanded
• New organisms added:
  • Chara
  • Methanogens
  • Nitrifying bacteria