**2.6 Organic matter**

The distribution of earthworms is greatly influenced by the distribution of organic matter. Soils that are poor in organic matter do not usually support large numbers of earthworms (Edwards and Bohlen, 1996). Several workers have reported a strong positive correlation between earthworm number and biomass and the organic matter content of the soil (Doube *et al.,* 1997; Ismail, 2005).

### **2.7 Soil texture**

88 Management of Organic Waste

Bouché (1971, 1977), also recognised three major groups based on ecological strategies: the epigeics (Épigés), anecics (Anéciques) and endogeics (Éndogés). Epigeic earthworms live on the soil surface and are litter feeders. Anecic earthworms are topsoil species, which predominantly form vertical burrows in the soil, feeding on the leaf litter mixed with the soil. Endogeic earthworms preferably make horizontal burrows and consume more soil than

Earthworms occur all over the world, but are rare in areas under constant snow and ice, mountain ranges and areas almost entirely lacking in soil and vegetation (Edwards and Bohlen, 1996). Some species are widely distributed, which are called peregrine, whereas others, that are not able to spread successfully to other areas, are termed as endemic

The distribution of earthworms in soil is affected by physical and chemical characters of the soil, such as temperature, pH, moisture, organic matter and soil texture (Edwards and

The activity, metabolism, growth, respiration and reproduction of earthworms are all

pH is a vital factor that determines the distribution of earthworms as they are sensitive to the hydrogen ion concentration (Edwards and Bohlen, 1996; Chalasani *et al.,* 1998). pH and factors related to pH influence the distribution and abundance of earthworms in soil (Staaf, 1987). Several workers have stated that most species of earthworms prefer soils with a neutral pH (Jairajpuri, 1993; Edwards and Bohlen, 1996). There is a significant positive correlation between pH and the seasonal abundance of juveniles and young adults (Reddy and Pasha, 1993).

Prevention of water loss is a major factor in earthworm survival as water constitutes 75-90% of the body weight of earthworms (Grant, 1955). However, they have considerable ability to survive adverse moisture conditions, either by moving to a region with more moisture (Valle *et al.,* 1997) or by means of aestivation (Baker *et al.,* 1992). Availability of soil moisture determines earthworm activity as earthworm species have different moisture requirements in different regions of the world. Soil moisture also influences the number and biomass of

The distribution of earthworms is greatly influenced by the distribution of organic matter. Soils that are poor in organic matter do not usually support large numbers of earthworms (Edwards and Bohlen, 1996). Several workers have reported a strong positive correlation

epigeic or anecic species, deriving their nourishment from humus.

influenced greatly by temperature (Edwards and Bohlen, 1996).

**2.1 Distribution of earthworms** 

(Edwards and Lofty, 1972).

Bohlen, 1996).

**2.4 pH** 

**2.5 Moisture** 

earthworms (Wood, 1974).

**2.6 Organic matter** 

**2.3 Temperature** 

**2.2 Factors affecting earthworm distribution** 

Soil texture influences earthworm populations due to its effect on other properties, such as soil moisture relationships, nutrient status and cation exchange capacity, all of which have important influences on earthworm populations (Lavelle, 1992).
