2015 International Year of Soils
Biological diversity or 'biodiversity' is described as "the variability among living organisms from all sources, whether terrestrial, aquatic or marine." It includes the diversity within species (genetic diversity), between species (organism diversity) and of ecosystems (ecological diversity). Soil is one of nature's most complex ecosystems and one of the most diverse habitats on earth: it contains a myriad of different organisms, which interact and contribute to the global cycles that make all life possible. Nowhere in nature are species so densely packed as in soil communities; however, this biodiversity is little known as it is underground and largely invisible to the human eye.
Soil Biodiversity and AgricultureOur agricultural systems exert an important influence on soil organisms, including their activities and their biodiversity. Clearing forested land or grassland for cultivation affects the soil environment and drastically reduces the number and species of soil organisms. A reduction in the number of plant species with different rooting systems, in the quantity and quality of plant residues, or in soil organic matter content limits the range of habitats and foods for soil organisms. While the use of external inputs, particularly inorganic fertilizers and pesticides, can overcome some soil constraints to crop production, the overuse or mis-use of afro-chemicals has resulted in environmental degradation, particularly of soil and water recourses. The quality and health of soils largely determine agricultural production and sustainability, environmental quality and, as a consequence of both, has bearing on plant, animal and human health. Improving soil biodiversity is vital to ensuring soil health and further food and nutrition security. Agricultural systems and afro-ecological practices that dedicate great care to nurturing soil biodiversity, such as organic farming, zero-tillage, crop rotation and conservation agriculture, can sustainably increase farm productivity without degrading the soil and water resources.
The Soil Food Web
When diverse soil organisms interact with one another and with the plants and animals in the ecosystem, they form a complex web of ecological activity called the soil food web. The resilience of the food web in inextricably linked to the biodiversity within the soil.