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Earthworms prefer a moist, but well-aerated environment. They do not live under anaerobic conditions, nor do they thrive in coarse sands. Because fungi and bacteria that grow on decaying organic matter are their principal food sources, earthworms generally grow best where farm manure or other decomposable organic materials are added to the soil. A few species are reasonably tolerant to low pH, but most earthworms thrive best where the soil is not too acidic and has abundant calcium.
Most earthworms are quite sensitive to excess salinity. Enchytraeid worms are much more tolerant of acid conditions and are more active than earthworms in some forested Spodosols. Some earthworms burrow as deep as 1 to 2 meter into the profile, thereby avoiding unfavorable moisture and temperature conditions. However, in soils not insulated by residue mulches, a sudden heavy frost in the fall may decimate earthworm populations before they can move deeper into the soil profile.
A soil temperature of about 10 degree Celsius is optimum for Lumbricus terrestris. This temperature sensitivity, together with their preference for moist soil, probably accounts for the maximum earthworm activity.
Other factors that depress earthworm populations include predators like moles, mice and other certain mites and millipedes), very sandy soils because of abrasive effect of sharp sand grains, direct contact with ammonia fertilizer, application of certain insecticides and tillage. The last factor is often the overriding deterrent to earthworm populations in agricultural soils. Minimum tillage, with plenty of crop residues left as mulch on soil surface, is ideal for encouraging earthworms. Soil moisture is a basic limiting factors affecting the activity of earthworm. Earthworms exhibit cutaneous respiration and so their populations and distributions in soils are mainly affected by the soil moisture. Some earthworms can even survive in water-saturated soils, if there is dissolved oxygen in water. However, in many cases, extremely waterlogged soils prompt them to ascend to the surface due to a lack of oxygen or the toxic compounds produced by anaerobic bacteria in saturated conditions.
Earthworms die in soil that remains at 85-90°F for a sustained period. Similar to their behavior under water stress, they move downward when exposed to high soil temperatures. Ideal soil temperatures for earthworm growth and activities are 55-80°F. Earthworms feed on organic residues in the soil, and that's why quality and quantity of soil organic matter are also important that influence the earthworm populations.
Because of their sensitivity to soil and other environmental factors, the numbers of earthworms vary widely in different soils. In very acid soils, an average of fewer than one earthworm per square meter is common. On the other hand, more than 500 per square meter have been found under grassland and cropland enriched with animal manure and managed with minimum tillage. The numbers commonly found in arable soils range from 30 to 300 per square meter.
Most earthworms are quite sensitive to excess salinity. Enchytraeid worms are much more tolerant of acid conditions and are more active than earthworms in some forested Spodosols. Some earthworms burrow as deep as 1 to 2 meter into the profile, thereby avoiding unfavorable moisture and temperature conditions. However, in soils not insulated by residue mulches, a sudden heavy frost in the fall may decimate earthworm populations before they can move deeper into the soil profile.
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| Earthworm activity - soil science |
A soil temperature of about 10 degree Celsius is optimum for Lumbricus terrestris. This temperature sensitivity, together with their preference for moist soil, probably accounts for the maximum earthworm activity.
Other factors that depress earthworm populations include predators like moles, mice and other certain mites and millipedes), very sandy soils because of abrasive effect of sharp sand grains, direct contact with ammonia fertilizer, application of certain insecticides and tillage. The last factor is often the overriding deterrent to earthworm populations in agricultural soils. Minimum tillage, with plenty of crop residues left as mulch on soil surface, is ideal for encouraging earthworms. Soil moisture is a basic limiting factors affecting the activity of earthworm. Earthworms exhibit cutaneous respiration and so their populations and distributions in soils are mainly affected by the soil moisture. Some earthworms can even survive in water-saturated soils, if there is dissolved oxygen in water. However, in many cases, extremely waterlogged soils prompt them to ascend to the surface due to a lack of oxygen or the toxic compounds produced by anaerobic bacteria in saturated conditions.
Earthworms die in soil that remains at 85-90°F for a sustained period. Similar to their behavior under water stress, they move downward when exposed to high soil temperatures. Ideal soil temperatures for earthworm growth and activities are 55-80°F. Earthworms feed on organic residues in the soil, and that's why quality and quantity of soil organic matter are also important that influence the earthworm populations.
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| Earthworms burrow - Soil Science - Soil Ecology |
Because of their sensitivity to soil and other environmental factors, the numbers of earthworms vary widely in different soils. In very acid soils, an average of fewer than one earthworm per square meter is common. On the other hand, more than 500 per square meter have been found under grassland and cropland enriched with animal manure and managed with minimum tillage. The numbers commonly found in arable soils range from 30 to 300 per square meter.
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| Earthworm-Soil Engineers- Soil Science |
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