The Science of Vermicomposting

Compost Analysis


Composts and vermicomposts are not all the same. As a producer I wanted to make sure that I was selling a quality product. As a gardener you may want to know more information about what you are using on your plants. Below are analysis reports for Devine Gardens vermicompost. The first is a compost analysis report from Penn State which gives results for physical and chemical properties. The second is a foodweb analyis report from Soil Foodweb that shows what microorganisms are present and at what levels. 
What do the test results mean? Both labs provide interpretation guides to show what characteristics quality composts should have. You can use their guides to compare with Devine Gardens vermicompost. From the results, I know that I am selling a quality product.

Click here for the 2014 and 2015 results. You may notice that the soluble salts are higher. That is common in vermicomposts especially high quality like Devine Gardens. The nitrates, calcium, potassium and magnesium all combine to increase the level of soluble salts. Notice that the actual level of sodium is relatively low. Devine Gardens is rich - I suggest 10% added to potting soils and less for light feeders like flowers.


Compost first goes through an active thermophilic stage where the temperature is preferably between 131 degrees or greater. Then it goes through a maturing stage at lower mesophilic temperatures (under 110 degrees). Composting is a good way to stabilize great amounts of waste. Its quality is determined by its feedstock and how it was managed with regards to aerating, moisture, temperature and amount of time in both stages. Compost improves the physical structure of soil, supplies organic matter, adds beneficial microorganisms, buffers pH, stabilizes soluble nutrients and helps plants use them better and can encourage growth. Research has shown that compost helps suppress diseases and pests.
Vermicompost also has two stages. The first is an active stage involving earthworms and microorganisms at a mesophilic temperature preferrably between 59 degrees and 77 degrees. The earthworms mix and fragment the waste providing more surface area for microorganisms. When the earthworms have worked through the waste they move to an area with more food. Then the second stage occurs where the microorganisms finish stabilizing the waste.  Vermicompost generally stabilizes smaller amounts of waste. The quality again is determined by management of moisture, feedstock, temperature, aeration and also a good concentration of earthworms. Because of the intrinsic value that the earthworms bring to the dynamics of the process, vermicompost has the above characteristics of compost but to a higher degree. Vermicompost also brings about additional qualities that make them superior organic amendments as explained below.
The effects of vermicompost have been studied on tomatos, cucumbers, peppers, peas, lettuce, cabbages, radishes, mushrooms, onions, corn, oats, wheat, tobacco, soybean, peanut, chicory and ryegrass, chrysanthemums, petunias, marigolds, corn flowers, begonias, coleus, raspberries, strawberries, grapes, cloves and black peppers and others. The plant growth medium used for comparisons has included mixes of sand, peat, commercial greenhouse medias and field soils. I hope that you will try using Devine Gardens vermicompost on your plants and you have good results too.

Growth and development of plants

Positive results on growth and development of plants include greater economic yields, faster germination rates, earlier flowering, larger yieds, better quality crops, greater leaf areas, higher plant weights, increased root lengths, better establishment of cuttings and higher vitamin content of plant. One reason is that the huge and diverse amount of microorganisms in vermicompost slowly break down organic matter and make more nutrients available for plants to use.
Another reason is a little complicated. Microorganisms produce plant growth hormones (PGH). Since vermicompost has a great amount of microorganisms it therefore contains a lot of PGH but because they are soluble and break down quickly they tend to be ineffective. Vermicomposts also have large amount of humates known to produce positive plant growth. Humates are slowly released to plants.  In a detailed structural analysis of vermicompost the PGH auxin was identified attached to humic acids. (Canellas,L. P., Olivares, F. L., Okorokova, A. L., and Facanha, A. R. 2000. Humic acids isolated from earthworm compost ehance root elongation, lateral root emergence, and plasma H+ -ATPase activity in maize roots. Plant Physiol. 130: 1951-1957). If the PGH in vermicompost are attaching or being absorbed by the humates then the PGH would no longer be soluble and have little effect. They would slow release along with the humates. This could be the major reason why vermicompost helps plants grow so well. Very interesting!

Disease suppression

The ability of vermicompost to aid plants in disease suppression has been studied with many positive results. Possible reasons could be the large biological diversity of microorganisms, antagonistic microorganisms produced from the vermicompost, the plants are stronger because of more pathogen suppressive properties from the vermicompost and SAR (system acquired resistance).
An amazing video was made by Jean Bonhotal and Allison Jack through Cornell Waste Management Institute titled Vermicompost - A Living Soil Amendment. The link for it is below. You will learn a lot from watching it.

Bonhotal J and Jack A. Vermicompost - A Living Soil Amendment. Cornell Waste Management Institute. 2010. 9:10 min.
Do you want to check out more science behind Vermicomposting? Click here for more resources!