Nitrogen & Phosphorus Cycles: Always Recycle! Part 2 - Crash Course Ecology #9

Introduction to Nutrient Cycles00:00:00

Living organisms require nutrients like nitrogen and phosphorus for DNA, proteins, and cell structure, yet these are often not readily accessible despite being abundant in the environment.

The Nitrogen Cycle00:01:46

Nitrogen gas makes up 78% of the atmosphere but is held by strong triple bonds. Specialized nitrogen-fixing bacteria use the enzyme nitrogenase to convert this gas into ammonia, which plants can then assimilate.

The Phosphorus Cycle00:05:15

Unlike nitrogen, phosphorus does not circulate through the atmosphere. It exists primarily in rocks and soil, entering biological systems through weathering and erosion before eventually settling back into deep sediment.

Human Impact and Synthetic Fertilizers00:07:23

Humans have significantly altered these cycles by mass-producing synthetic fertilizers. While this increases food production, it disrupts natural ecosystems by overloading them with nitrogen and phosphorus.