Definition

“Land degradation” means reduction or loss of the biological or economic productivity and complexity of rainfed cropland, irrigated cropland, or range, pasture, forest and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as:

1. soil erosion caused by wind and/or water;

2. deterioration of the physical, chemical and biological or economic properties of soil; and

3. long-term loss of natural vegetation. [33]

Disregarding the issue of long-term loss of natural vegetation (which will be covered in this project under the headings of deforestation and biodiversity), land degradation primarily relates to a reduction in soil quality and quantity as an input to the production of agricultural crops. But there are also off-site effects, such as loss of watershed function.

Soil quality relates to the chemical, physical, and biological properties of the soil, and how these are distributed throughout the soil profile. Scientists use an array of indicators to describe soil quality: pH, organic matter content, plant-available nutrients, porosity, grain size distribution, water permeability and retention capacity, topsoil depth, presence of chemicals toxic to plants or plant consumers, etc. These properties vary vertically within the soil profile and horizontally from site to site. They also interact. Therefore, soil quality cannot easily be described by one variable or an index.