Soil Biodiversity: Billions in a Handful

The claim that a handful of healthy soil contains more organisms than humans on Earth is scientifically sound.

The Numbers

• Bacteria: 1 million to 650 million per gram.
• Fungi, archaea, viruses: likely outnumber bacteria in many soils.
• Nematodes, protozoa, microarthropods: thousands to millions per gram.

Finding Peer-Reviewed Sources

Excellent soil microbiology departments with published research include:

• Texas A&M University
• University of Colorado Boulder
• Duke University

Search their soil ecology or microbiology faculty publications for specific studies quantifying soil biodiversity.

This staggering diversity underpins soil fertility, nutrient cycling, and plant health.