Slow growers - El Natural

dwalstad · 05-03-2009, 05:23 PM

Quote:

Originally Posted by queijoman

Is it really true that a plain substrate (such as pea gravel) has as much beneficial bacteria as soil? Soil, by virtue of smaller particles has exponentially more surface area.

You may be in the wrong forum, but you are on the right track.

Soil will have much, much more bacteria than gravel. For example, coarse sand of 1-2 mm diameter has 11 cm2/g suface area. Silt has 454 and clay has 8,000,000 cm2/g.* Increased surface area provides increased attachment sites for bacteria. That's why soil has billions of bacteria per gram and sand/gravel has much, much less.

You have to think from the bacterium perspective. You can live in a desert (gravel) or a Rain Forest (clay).

*Foth HD. 1978. Fundamentals of Soil Science. 6th Edition. John Wiley & Sons.