How Soil Is Formed

Abstract

Plants play a crucial role in the formation of soil; soil formation accelerated when the first plants wandered onland 400 million years ago. One of the conditions enabling plants to develop was that algae joined forces with fungi, which were better at absorbing phosphorus from the ground. However the first soils were formed by microorganisms. Their complex miniature worlds, so-called biofilms, are described and compared with human cities. Acids secreted by microbes and plant roots accelerate the weathering of minerals, and dead plant material helps to build up humus in the soil. But soil formation is a slow process, and one has to be ingenious to follow the phenomenon over long periods of time. You can take soil samples where glaciers are receding, and along the gradients from the coast towards the highest shoreline, in regions which are in a process of post-glacial rebound still rising after being depressed under the weight of the ice during the last ice age. This makes it possible to follow the soil formation process over thousands of years.

The flakes of inky thunderclouds

Above the convex whiteness of the glacier.

A lifeless river dressed in yellow till

And sun rays, glistering like spears at daybreak,

Pierce through the silent, silver sky

“Awake, oh Earth, awake!”—I cry

“Break free from this eternal coldness!

Transform your till and gravel into soil

And let the frigid puddles of the tundra

Be overgrown by reeds, green and unspoiled!”

The Earth is silent, and the pearly slabs of glaciers

Lie far beneath the icy sun, as in a trance.

Indeed, no human measure ever

Can wrap around this ancient, vast expanse.

N. Zagorskaya