Of all the members of the floor food web, earthworms need the the very least introduction. Most people end up being familiar v these soft, slimy, invertebrates at a young age. Earthworms are hermaphrodites, an interpretation that they exhibition both male and female characteristics.

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They are significant decomposers the dead and also decomposing essential matter, and derive your nutrition indigenous the bacteria and also fungi that prosper upon these materials. Lock fragment necessary matter and also make major contributions come recycling the nutrients it contains.

Earthworms occur in most temperate soils and also many dry soils. Lock are separated into 23 families, much more than 700 genera, and an ext than 7,000 species. They range from an inch to 2 yards in length and also are uncovered seasonally at all depth in the soil.

In terms of biomass and also overall activity, earthworms conquer the civilization of floor invertebrates, including arthropods.


Earthworms generate lots of casts per acre every year, dramatically altering soil structure.

Credit: Clive A. Edwards, The Ohio State University, Columbus. Please call the Soil and Water Conservation society at pubs


A corn sheet pulled into a night crawler burrow.

Credit: Soil and Water monitoring Research Unit, research Service, St. Paul, Minnesota. Please contact the Soil and Water Conservation culture at pubs

What execute Earthworms Do?

Earthworms dramatically transform soil structure, water movement, nutrient dynamics, and also plant growth. They are not crucial to all healthy soil systems, however their existence is typically an indicator that a healthy system. Earthworms carry out several useful functions.

Stimulate microbial activity. Return earthworms derive your nutrition indigenous microorganisms, many more microorganisms are existing in their feces or casts than in the organic issue that lock consume. As organic matter passes with their intestines, it is fragmented and also inoculated with microorganisms. Boosted microbial task facilitates the cycling of nutrient from necessary matter and their switch into forms readily taken increase by plants.

Mix and accumulation soil. As they consume organic matter and mineral particles, earthworms excrete wastes in the form of casts, a kind of soil aggregate. Charles Darwin calculated the earthworms have the right to move large amounts of soil from the reduced strata to the surface and additionally carry organic matter down into deeper floor layers. A big proportion of soil passes v the guts of earthworms, and also they have the right to turn end the height six customs (15 cm) of floor in ten come twenty years.

Increase infiltration. Earthworms enhance porosity together they move through the soil. Some species make permanent burrows deep right into the soil. These burrows can persist long after the inhabitant has actually died, and also can it is in a significant conduit for floor drainage, an especially under heavy rainfall. At the exact same time, the burrows minimize surface water erosion. The horizontal burrowing of other varieties in the optimal several inch of soil increases overall porosity and drainage.

Improve water-holding capacity. By fragmenting necessary matter, and also increasing floor porosity and also aggregation, earthworms can considerably increase the water-holding volume of soils.

Provide networks for source growth. The channels made through deep-burrowing earthworms space lined with readily available nutrients and make it much easier for roots to permeate deep into the soil.

Bury and also shred plant residue. Plant and crop residue are gradually hidden by cast material deposit on the surface and as earthworms pull surface residue into their burrows.


A mixture that soil and organic issue within an earthworm burrow. Earthworms incorporate huge amounts of essential matter right into the soil.

Credit: Clive A. Edwards, The Ohio State University, Columbus. Please call the Soil and Water Conservation culture at pubs


Some worms live in irreversible vertical burrows such together these. Others move horizontally close to the surface, filling their burrow through casts as they move.

Credit: north Appalachian experimental Watershed, research study Service, Coshocton, Ohio. Please call the Soil and Water Conservation culture at pubs

Where space Earthworms?

Different varieties of earthworms inhabit various parts of the soil and also have distinct feeding strategies. They have the right to be separated right into three major ecological groups based on their feeding and also burrowing habits. Every three teams are common and important to floor structure.

Surface soil and litter types – Epigeic species. These types live in or near surface tree litter. They space typically small and are adjusted to the highly variable moisture and also temperature conditions at the soil surface. The worms uncovered in compost piles are epigeic and also are i can not qualify to survive in the low organic matter setting of soil.

Upper soil species – Endogeic species. Some types move and also live in the top soil strata and feed mostly on soil and associated organic matter (geophages). They perform not have permanent burrows, and also their short-lived channels end up being filled with actors material together they relocate through the soil, significantly passing it through their intestines.

Deep-burrowing species – Anecic species. These earthworms, which space typified by the “night crawler,” Lumbricus terrestris, inhabit an ext or less permanent burrow systems that may extend several meters right into the soil. They feed mostly on surface ar litter the they pull into their burrows. They may leave plugs, organic matter, or cast (excreted soil and also mineral particles) impede the mouth of your burrows.

Looking for Earthworms?

It is simple to identify whether you have actually an adequate population of earthworms in your soil. Watch for your casts in the forms of little piles the soil, mineral particles, or organic matter at the soil surface. They have the right to be seen relocating over the soil surface ar or also breeding, particularly on warm, wet nights. Intake a spade full of moist soil into a bucket or ~ above a sheet of plastic, and also sort with for earthworms. Have the right to you identify different species?To uncover the deep burrowing species, to water a dilute mustard solution onto the soil. Plenty of will quickly pertained to the soil surface in response to this irritant.

Abundance and Distribution that Earthworms

The bulk of temperate and also many tropic soils support far-ranging earthworm populations. A square yard of cropland in the unified States can contain indigenous 50-300 earthworms, or also larger populations in very organic soils. A similar area of grassland or pleasant woodlands will have actually from 100-500 earthworms. Based on their total biomass, earthworms room the predominant team of floor invertebrates in most soils.

The household of earthworms the is most vital in enhancing farming soil is Lumbricidae, which has the genuses Lumbricus, Aporrectodea, and also several others. Lumbricids originated in Europe and also have been transported by human tasks to many parts the the world. The united States has actually only one or two well-known native species of lumbricids. Rather were carried to this country by settlers (probably in potted plants from Europe), and were dispersed down the waterways.

Generally, lumbricids space much much more common in the north and east than in the drier south and also west of the joined States. They often tend to be more abundant in loam and clay loam and also even in silty soil, 보다 in sandy soil and heavy clay. Populations also build increase in irrigated soil. Earthworm populaces tend to rise with soil organic matter levels and also decrease through soil disturbances, such as tillage and also potentially harmful chemicals.


Casts at the soil surface ar are evidence that earthworms room shredding, mixing, and burying surface residue.

Credit: Soil and Water administration Research Unit, study Service, St. Paul, Minnesota. Please call the Soil and Water Conservation culture at pubs


This earthworm burrow is an opened in an otherwise crusted soil surface.

Credit: Clive A. Edwards, The Ohio State University, Columbus. Please contact the Soil and also Water Conservation culture at pubs

Interactions that Earthworms with other Members that the Food Web

The stays of earthworms and also microbes are carefully intertwined. Earthworms derive your nutrition from fungi, bacteria, and possibly protozoa and nematodes, and they encourage the activity of this organisms by shredding and increasing the surface ar area of essential matter and also making it more available to small organisms.

Earthworms also influence other soil-inhabiting invertebrates by changing the amount and distribution of organic matter and also microbial populations. Over there is good evidence the earthworm activity affects the spatial distribution of soil microarthropod neighborhoods in the soil.

Earthworms have few invertebrate enemies, other than flatworms and a species of parasitic fly. Their key predators are a wide selection of birds and also mammals that food upon them in ~ the floor surface.

Earthworms and Water Quality

Earthworms boost water infiltration and water hold capacity because their shredding, mixing, and also defecating boosts soil structure. In addition, burrows provide quick entry for water into and also through soil. High infiltration rates aid prevent pollution by minimizing runoff, erosion, and also chemical carry to surface waters.

There is worry that burrows may rise the move of pollutants, such as nitrates or pesticides, into groundwater. However, the activity of potential pollutants through soil is not a straightforward process and the is not clear once earthworm task will or will certainly not have actually a negative impact on groundwater quality.

Whether pollutants with groundwater counts on a variety of factors, consisting of the place of pollutants ~ above the surface ar or within soil, the quantity and intensity the rain, how well water move into and also through various other parts of the soil, and also characteristics that the burrows. The horizontal burrows the endogeic earthworms (such as Aporrectodea tuberculata, i beg your pardon are common in Midwestern fields) do not carry water and also solutes as deeply together the upright burrows of night crawlers (L. Terrestris) and other anecic species. Also vertical burrows, however, room not direct networks for water movement. They have actually bends and also turns and are lined v organic matter that adsorbs plenty of potential pollutants native the water.

Although over there is much more to learn around how earthworms affect water motion through soil, they plainly help minimize pollution of surface ar waters by improving infiltration rates and decreasing runoff.


A mound of organic issue was relocated aside to disclose the entrance to a burrow. L. Terrestris will quickly replug that burrow if that is mound is removed.

Credit: phibìc Appalachian experimental Watershed, research study Service, Coshocton, Ohio. Please contact the Soil and also Water Conservation society at pubs


L. Terrestris mating, and earthworm cocoons. Earthworms friend periodically transparent the year, other than when environmental problems are unfavorable. The worms form slime tube to assist adhere to every other throughout copulation which might take as lengthy as one hour.


After the worms separate, they each produce a cocoon. One or two worms will certainly hatch indigenous a cocoon after number of weeks. L. Terrestris cocoons are about a 4 minutes 1 inch long.

Credit: Clive A. Edwards, The Ohio State University, Columbus. Please contact the Soil and Water Conservation culture at pubs

Bug Biography: Night Crawlers and also Tillage

The substitution of standard tillage by no-till or conservation tillage is progressively common and also widely adopted in the joined States and elsewhere. In this situations, earthworms, particularly the “night crawler,” Lumbricus terrestris L., are particularly important. Earthworms come to be the main agent because that incorporating chop residue into the floor by pulling some into their burrows and by progressively burying the remainder under casts set on the soil surface.

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In lessened tillage systems, surface ar residue build up and also triggers growth in earthworm populations. Earthworms need the food and habitat provided by surface residue, and they eat the fungi the become an ext common in no-till soils. Together earthworm populations increase, they pull an ext and more residue into their burrows, helping to mix organic matter right into the soil, improving soil structure and water infiltration. residence | | website Map | Civil rights | FOIA | plain Writing | availability Statement

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