2.2.2. Soil formation
Soil formation is an important ecosystem service provided by
soil biota (Breemen and Buurman, 2002). Earthworms are the
most important component of this soil in this respect and in
the maintenance of soil structure and fertility (Stockdill, 1982;
Lee, 1985; Edwards, 2004). Earthworm populations in each of
the selected fields were assessed to estimate the quantity of
soil formed ha−1yr−1 (Sandhu et al., 2005).