Landscaping
Earthworms and Vermicompost for Soil Health
A guest post on soil health for the Florida home and farm from our friend Robert A. Kluson, Ph.D., of Sarasota County.
Dear Reader, continuing this blog on the important concept of Soil Health, I am highlighting the research to formulate recommendations for best practices of soil management.
One such concept is the critical role of earthworms and vermicompost amendments in promoting healthy soil ecosystems for lawns, gardens, farms and ranches. In order to help you learn about these advances, I’m pleased to provide information and resources, both from FL and worldwide, in this blog for your use . . .
1) Earthworms; USDA NRCS – see https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/soils/health/biology/?cid=nrcs142p2_053863
Of all the members of the soil food web and in terms of biomass and overall activity, earthworms dominate the world of soil invertebrates, including arthropods. Earthworms dramatically alter soil structure, water movement, nutrient dynamics, and plant growth.
They are major decomposers of dead and decomposing organic matter, and derive their nutrition from the bacteria and fungi that grow upon these materials. They fragment organic matter and make major contributions to recycling the nutrients it contains.
Although earthworms derive their nutrition from microorganisms, many more microorganisms are present in their feces or casts than in the organic matter that they consume.
As organic matter passes through their intestines, it is fragmented and inoculated with microorganisms. Increased microbial activity facilitates the cycling of nutrients from organic matter and their conversion into forms readily taken up by plants.
Earthworms generate tons of casts per acre each year, dramatically altering soil structure.
2) Earthworm Ecology; Earthworm Society of Britain; Wiggley World – see http://www.earthwormsoc.org.uk/earthworm-ecology and http://www.wigglyworld.org/earthworm-ecology/
Different species of earthworms belong to different habitats of soil ecosystems. The three primary habitats and ecotypes of earthworms are the following:
a) epigeic or leaf litter on the soil surface. These species tend not to make burrows but live in and feed on the leaf litter.
b) endogeic or topsoil/subsoil. These species make horizontal burrows through the soil to move around and to feed and they will reuse these burrows to a certain extent.
c) anecic or deep soil. These species make permanent vertical burrows in soil. They feed on leaves on the soil surface that they drag into their burrows. They make casts on the surface, and also middens (piles of casts) around the entrance to their burrows.
The physical properties of these soil habitats are very important to the life of earthworms. Earthworms are sensitive to changes in the temperature, moisture and pH of the soil. Salt content, texture and aeration also play a role in providing a suitable habitat. Most earthworms prefer to live in neutral or slightly acidic soil, but exceptions do exist. Because the physical properties of soil are so important, earthworm populations can be devastated when chemicals, insecticides and certain fertilizers are introduced.
3) Earthworm, suborder Crassiclitellata, cohort Terrimegadrili; UF/IFAS – see http://edis.ifas.ufl.edu/in946
There are thousands of described species of earthworms and likely many thousands more that are yet to be described. Individual species are found in most habitats worldwide. Different earthworm species are found in natural, agricultural, and urban environments; as of the mid 1990s there were 51 earthworm species reported in Florida.
Some species are known to occur only in the northern portion of the state and South Florida is the only location in the United States where some tropical earthworm species are found, in addition that some earthworm species are unique to Florida. The most commonly cultivated earthworms in Florida are the tiger worm (Eisenia fetida), the red wiggler (E. andrei), and one type of nightcrawler (Dendrobaena veneta).
Earthworms have various important ecological roles. The most easily recognized is that of organic matter decomposition. Decomposing plant matter is ingested and then expelled in a more broken down form, greatly speeding up the decomposition process.
Worm castings typically have higher microbial activity and higher concentration of plant-available nutrients than the original material and, therefore, earthworms aid in nutrient cycling.
Additionally, activity of anecic worms moves organic matter from the soil surface deeper into the soil profile. Tunneling by earthworms helps break compaction, which improves aeration and water infiltration in the soil profile. The castings and other organic residues from earthworms improve soil structure.
Earthworms provide a principal food source for various wildlife including birds, reptiles, insects, and moles
4) The Benefits of Vermicompost; NC Worm Farm News – see http://ncwormfarm.com/blog/?p=23
Vermicompost (also called `worm compost`, vermicast, worm castings, worm humus or worm manure) is the end-product of the breakdown of organic matter and waste products by using some species of earthworm in a controlled environment. Vermicompost is a nutrient-rich, natural fertilizer and soil conditioner. The process of producing vermicompost is called `vermicomposting’. Worm castings are small grains which are dark black in color. They look very similar to coffee grounds. When this material is combined with other non-digested materials, it is referred to as vermicompost.
Research on vermicompost has identified the following properties and benefits:
a) there are beneficial microbes that also break down the organic materials in vermicomposting. As the organisms decompose the material, they change its chemical makeup and secretions in the worm’s intestinal tract add concentrated nutrients as the soil passes thru.
b) in addition, the cooperation between the worms and microbes produce humic acid and plant growth hormones. The humic acid binds to minerals and nutrients in the soil. It protects them from being degraded by the UV rays and/or washed out of the soil. The acid “holds” them in the soil in a form which can be readily be absorbed by the plants. And lastly, the plant growth hormones cause earlier germination, larger crop yields, and much deeper root development.
c) vermicompost may have up to a 1,000 times higher microbial population than regular, pile compost. Compost piles break down materials using bacteria that thrive in high temperatures. These high temperatures kill off some of the microbes. But with vermicompost, waste is broken down aerobically at moderate temperatures. This permits a much wider spectrum of microorganisms to develop in the final product.
d) in addition, vermicompost additions have been shown to help increase a plant’s resistance to disease. The theory is that the high microbial content of vermicompost increases microbial competition for the nutrients in the soil makes it harder for the harmful microbes to survive, i.e., the soil’s health improves.
e) vermicompost can be produced in 1/3 the time as regular compost.
5) Vermicompost, A Living Soil Amendment; Cornel Universtiy – see http://cwmi.css.cornell.edu/vermicompost.htm
The uses of vermicompost include plant nutrient management and the suppression of plant diseases.
For example, vermicompost can be an important component of potting media for producing vegetable transplants without synthetic fertilizers. Temperature control for optimal temperature ranges for a variety of vegetable crops was identified as a significant factor in the performance of potting media containing vermicompost. Vermicompost-amended potting soil protects cucumbers from Pythium aphanidermatum, a seed-infecting pathogen.
6) Vermicomposting; Eco Worms – see http://www.eco-worms.com/vermicomposter/the-vermicomposting/
Vermicompost may not contain adult worms, if screened, but can contain earthworm eggs which can inoculate soil and potting media amended with vermicompost. Earthworm reproduction involves the production of cocoons in which their young ones or embryos develop.
When the earthworm becomes sexually mature, a saddle shaped structure (clitellum) becomes conspicuous on its body. Earthworms are hermaphroditic (i.e., having both male and female sex organs) but mate to exchange sperm. The clitellum becomes a sheath containing collected eggs and sperm from the genital openings of the worm and slides off from the head of the worm. As it separates from the worm, its ends are sealed. It now becomes a cocoon. The eggs and sperm fuse, resulting in embryos. The embryos grow inside the cocoon, absorbing the stored nutritive material. Each cocoon may contain two to twenty embryos. Depending upon favorable conditions, young worms hatch from cocoons in three weeks and mature in ten to fifty weeks.
7) Vermicomposting; UF/IFAS – see http://sfyl.ifas.ufl.edu/lawn-and-garden/vermicomposting/
You can build bins to use worms to do your composting for you. Worm bins can take up less space than traditional compost bins and can even be kept inside. Vermicomposting is a great way to compost if you live in an apartment or if your main source of compost materials is kitchen scraps.
One pound of worms can be fed half a pound of kitchen scraps per day. You can feed them daily or weekly. After two or three months, the worms will have turned the scraps and bedding into usable compost. For specifications in making your own worm bin refer to this website.
4) What Is the Difference Between Composting and Vermicomposting?; SFGate – see http://homeguides.sfgate.com/difference-between-composting-vermicomposting-40955.html
Plant and animal material can be decomposed into a soil amendment through both the processes of pile composting and vermicomposting. Several advantages have been identified with the use of vermicomposting over pile composting and include the following:
a) aeration – pile composting systems require someone to turn the compost each week with a shovel or pitchfork to aerate the middle of the compost pile so that the inner part of the pile heats up above 160o F. In a vermicomposting system, worms tunnel in the soil, creating pathways for air to travel so turning the pile is not necessary.
b) fertilizer – vermicompost contains more nutrients than other forms of compost. Vermicomposting also creates a concentrated liquid as a by-product of the composting process which can be collected in a tray beneath the vermicompost bin, and diluted with water to form a “compost tea”, i.e., a nutrient-rich drink for established plants.
I hope that this information was interesting and useful to improving the soil management of your lawns, gardens, farms and ranches.
Robert A. Kluson, Ph.D.
UF/IFAS Extension Sarasota County
Soil Health News for the Florida Home and Farm
