10.4. THE IMPORTANCE OF SOIL

Terrestrial ecosystems depend on soil. Without soil, there would be no agriculture, for instance. The proper use of soil and conservation measures are necessary to protect it from degradation. The destruction or degradation of soil creates a serious loss because recovery is a very slow process.

	. Loss of vegetation, specially trees and shrubs, leaves soil without protection from erosion and reduces the soil´s capacity to retain water.
	. Rain washes away sediments and causes soil loss.

The main causes of soil degradation include:

• Pollution. Accumulation of toxic substances like mercury in the soil can make it not suitable for agriculture. Toxic substances are absorbed by plants, making them dangerous to eat.
• Soil compaction. Soil particles are pressed together. This results in loss of porosity and makes it difficult for rain to infiltrate the soil. Deforestation and traffic from agricultural machinery lead to soil compaction.
• Salinization. Accumulation of mineral salts in the topsoil. This can be caused naturally or by improper irrigation.

A complete loss of soil is generally produced by erosion. This process is called desertification. It can be caused by natural factors or human activities.