What Effect Do Small Burrowing Animals And Earthworms Have On The Rocks And Soil In The Ground?

Chapter 8:  EARTHWORMS
by Clive A. Edwards, The Ohio Land Academy

THE LIVING SOIL: EARTHWORMS

Of all the members of the soil food web, earthworms need the least introduction. Well-nigh people become familiar with these soft, slimy, invertebrates at a immature historic period. Earthworms are hermaphrodites, meaning that they showroom both male person and female person characteristics.

They are major decomposers of dead and decomposing organic matter, and derive their nutrition from the leaner and fungi that grow upon these materials. They fragment organic matter and make major contributions to recycling the nutrients information technology contains.

Earthworms occur in nearly temperate soils and many tropical soils. They are divided into 23 families, more 700 genera, and more than 7,000 species. They range from an inch to two yards in length and are found seasonally at all depths in the soil.

In terms of biomass and overall activity, earthworms dominate the world of soil invertebrates, including arthropods.

Figure 1: Earthworms generate tons of casts per acre each year, dramatically altering soil structure. Credit: Clive A. Edwards, The Ohio State University, Columbus.	Figure 2: A corn leaf pulled into a dark crawler burrow. Credit: Soil and Water Direction Research Unit, USDA-Agricultural Research Service, St. Paul, Minnesota.

WHAT DO EARTHWORMS DO?

Earthworms dramatically alter soil construction, water movement, food dynamics, and plant growth. They are not essential to all healthy soil systems, but their presence is usually an indicator of a salubrious system. Earthworms perform several beneficial functions.

Stimulate microbial activity. Although earthworms derive their nutrition from microorganisms, many more than microorganisms are present in their feces or casts than in the organic thing that they consume. As organic thing passes through their intestines, it is fragmented and inoculated with microorganisms. Increased microbial activity facilitates the cycling of nutrients from organic affair and their conversion into forms readily taken up by plants.

Mix and aggregate soil. As they consume organic matter and mineral particles, earthworms excrete wastes in the form of casts, a blazon of soil amass. Charles Darwin calculated that earthworms can motility large amounts of soil from the lower strata to the surface and also carry organic matter down into deeper soil layers. A big proportion of soil passes through the guts of earthworms, and they tin can turn over the top half-dozen inches (fifteen cm) of soil in ten to twenty years.

Increase infiltration. Earthworms enhance porosity as they move through the soil. Some species make permanent burrows deep into the soil. These burrows can persist long subsequently the inhabitant has died, and can be a major conduit for soil drainage, particularly under heavy rainfall. At the same time, the burrows minimize surface water erosion. The horizontal burrowing of other species in the elevation several inches of soil increases overall porosity and drainage.

Ameliorate h2o-belongings capacity. By fragmenting organic matter, and increasing soil porosity and aggregation, earthworms can significantly increase the water-property capacity of soils.

Provide channels for root growth. The channels made past deep-burrowing earthworms are lined with readily available nutrients and brand it easier for roots to penetrate deep into the soil.

Coffin and shred establish residual. Plant and ingather residue are gradually buried by bandage textile deposited on the surface and as earthworms pull surface residue into their burrows.

WHERE ARE EARTHWORMS?

Dissimilar species of earthworms inhabit different parts of the soil and have distinct feeding strategies. They can be separated into three major ecological groups based on their feeding and burrowing habits. All three groups are mutual and important to soil structure.

Surface soil and litter species – Epigeic species. These species live in or near surface plant litter. They are typically small and are adapted to the highly variable moisture and temperature weather condition at the soil surface. The worms found in compost piles are epigeic and are unlikely to survive in the low organic matter surround of soil.

Upper soil species – Endogeic species. Some species move and live in the upper soil strata and feed primarily on soil and associated organic matter (geophages). They do not accept permanent burrows, and their temporary channels become filled with cast material every bit they movement through the soil, progressively passing it through their intestines.

Deep-burrowing species – Anecic species. These earthworms, which are typified by the "night crawler," Lumbricus terrestris, inhabit more or less permanent burrow systems that may extend several meters into the soil. They feed mainly on surface litter that they pull into their burrows. They may leave plugs, organic matter, or bandage (excreted soil and mineral particles) blocking the mouth of their burrows.

LOOKING FOR EARTHWORMS?

It is easy to decide whether y'all have an acceptable population of earthworms in your soil. Look for their casts in the forms of little piles of soil, mineral particles, or organic matter at the soil surface. They can be seen moving over the soil surface or even convenance, particularly on warm, damp nights. Dump a spadeful of moist soil into a bucket or onto a canvass of plastic, and sort through for earthworms. Can you lot identify different species?  To observe the deep burrowing species, pour a dilute mustard solution onto the soil. Many will rapidly come to the soil surface in response to this irritant.

ABUNDANCE AND DISTRIBUTION OF EARTHWORMS

The majority of temperate and many tropical soils back up significant earthworm populations. A square m of cropland in the The states can comprise from 50-300 earthworms, or even larger populations in highly organic soils. A like area of grassland or temperate woodlands will have from 100-500 earthworms. Based on their total biomass, earthworms are the predominant group of soil invertebrates in most soils.

The family of earthworms that is nigh important in enhancing agricultural soil is Lumbricidae, which includes the genuses Lumbricus, Aporrectodea, and several others. Lumbricids originated in Europe and accept been transported by human activities to many parts of the world. The United States has only one or 2 known native species of lumbricids. Others were brought to this state by settlers (probably in potted plants from Europe), and were distributed down the waterways.

More often than not, lumbricids are much more common in the northward and e than in the drier south and west of the United States. They tend to exist more than arable in loam and clay loam and fifty-fifty in silty soil, than in sandy soil and heavy dirt. Populations also build upward in irrigated soil. Earthworm populations tend to increase with soil organic affair levels and subtract with soil disturbances, such as tillage and potentially harmful chemicals.

Figure v: Casts at the soil surface are evidence that earthworms are shredding, mixing, and burying surface balance. Credit: Soil and H2o Direction Research Unit of measurement, USDA-Agricultural Research Service, St. Paul, Minnesota.	Figure vi: This earthworm burrow is an opening in an otherwise crusted soil surface. Credit: Clive A. Edwards, The Ohio State University, Columbus.

INTERACTIONS OF EARTHWORMS WITH OTHER MEMBERS OF THE Food WEB

The lives of earthworms and microbes are closely intertwined. Earthworms derive their nutrition from fungi, bacteria, and mayhap protozoa and nematodes, and they promote the activeness of these organisms past shredding and increasing the area of organic matter and making it more available to pocket-size organisms.

Earthworms also influence other soil-inhabiting invertebrates by changing the corporeality and distribution of organic matter and microbial populations. In that location is good bear witness that earthworm activity affects the spatial distribution of soil microarthropod communities in the soil.

Earthworms take few invertebrate enemies, other than flatworms and a species of parasitic fly. Their main predators are a broad range of birds and mammals that prey upon them at the soil surface.

EARTHWORMS AND Water QUALITY

Earthworms improve h2o infiltration and h2o holding chapters because their shredding, mixing, and defecating enhances soil structure. In add-on, burrows provide quick entry for water into and through soil. Loftier infiltration rates assistance prevent pollution by minimizing runoff, erosion, and chemic transport to surface waters.

There is concern that burrows may increment the transport of pollutants, such every bit nitrates or pesticides, into groundwater. Nevertheless, the movement of potential pollutants through soil is not a straightforward process and it is not clear when earthworm activity volition or will not have a negative impact on groundwater quality.

Whether pollutants attain groundwater depends on a number of factors, including the location of pollutants on the surface or inside soil, the quantity and intensity of pelting, how well water moves into and through other parts of the soil, and characteristics of the burrows. The horizontal burrows of endogeic earthworms (such as Aporrectodea tuberculata, which are mutual in Midwestern fields) practise non transport water and solutes every bit deeply as the vertical burrows of night crawlers (L. terrestris) and other anecic species. Even vertical burrows, notwithstanding, are not direct channels for h2o move. They have bends and turns and are lined with organic thing that adsorbs many potential pollutants from the h2o.

Although there is much more to learn virtually how earthworms touch on water move through soil, they clearly help minimize pollution of surface waters by improving infiltration rates and decreasing runoff.

Figure 7: A mound of organic matter was moved aside to expose the entrance to a burrow. Fifty. terrestris volition apace replug its couch if its mound is removed. Credit: North Appalachian Experimental Watershed, USDA-Agricultural Research Service, Coshocton, Ohio.

Effigy 8: L. terrestris mating, and earthworm cocoons. Earthworms mate periodically throughout the year, except when ecology conditions are unfavorable. The worms course slime tubes to help adhere to each other during copulation which may have as long as an hour. After the worms separate, they each produce a cocoon. One or 2 worms will hatch from a cocoon subsequently several weeks. L. terrestris cocoons are nearly a quarter inch long. Credit: Clive A. Edwards, The Ohio Country University, Columbus.

BUG BIOGRAPHY:  Night Crawlers and Tillage

The substitution of conventional tillage by no-till or conservation tillage is increasingly common and widely adopted in the The states and elsewhere. In these situations, earthworms, peculiarly the "night crawler," Lumbricus terrestris L., are particularly important. Earthworms become the principal agent for incorporating crop residuum into the soil by pulling some into their burrows and by slowly burying the remainder under casts laid on the soil surface.

In reduced cultivation systems, surface residue builds up and triggers growth in earthworm populations. Earthworms need the nutrient and habitat provided past surface residue, and they eat the fungi that become more than common in no-till soils. Every bit earthworm populations increase, they pull more and more residue into their burrows, helping to mix organic matter into the soil, improving soil structure and water infiltration.

---

For more nigh soil biology, go to Further Reading

Render to the Table of Contents

<  Return to Chief Card  >

Source: https://web.extension.illinois.edu/soil/SoilBiology/earthworms.htm

Posted by: jacksonbabinfor.blogspot.com

Share this post