Guest Post - Farming with Earthworms!

I require students in my Experimental Ecology class at SDSU to design and conduct an outreach project related to their independent project research. This post was written by my students, Connor and John, as their outreach. They studied whether the combined effects of worms and fertilizer in garden soil have a synergistic effect on plant growth. Please enjoy their post below!

Langston University Aquaculture. Luresext.edu/aquaculture/earthworms.htm

You may think that worms are just gross slimy pests that only slither around and creep out grade school kids; however, as you will find out, earthworms are very important in many ecosystems. The Earthworm, Lumbricus terrestris, is used in compost in order to create rich organic wastes - a process known as VERMICOMPOSTING. Earthworms are used in farming and other plant rearing practices because they produce high levels of nitrogen, phosphorus and potassium, which are the limiting factors for the growth of plants. Worms help plants in many more ways too!

  

University of Illinois Extension. http://urbanext.illinois.edu/worms/live/

Disease Suppression

One way that the presence of worms can benefit plants is that they can suppress disease in some fruit bearing plants. In a study conducted in 2004, Johann Zaller found that plants treated with an extract from vermicompost were less vulnerable to a blight disease (Zaller 2012). So the worms acted as a disease fighter for the crops, not unlike the immune system and white blood cells of the human body.  While it’s true that there may be better tools that are available to treat plant disease, vermicomposting offers a method that is 100% biologically safe because no harmful chemicals are used to prevent disease; it’s just good old fashioned worm power! The power of the worm doesn't stop at biological disease suppression; worms are capable of much more.

Mixing/Aerating Soil

Another way these wonderful worms help out plants is by digging their way through the dirt. Their burrows allow for more oxygen and nutrients to reach deeper into the earth and to the roots of plants.  The most significant effect the worms have on the soil that surrounds them is their ability to drastically increase the amount of atmospheric nitrogen (N₂).  The worms do this by eating dirt that contains microorganisms that emit the nitrogen in the gut of the worm, and once the nitrogen is emitted, the worm poops out what it doesn’t need to survive, and this poop is very high in nitrogen (Drake and Horn 2007).

http://yelmworms.com/castings-vermicomposting.html

Increase in Nutrients

Vermicomposting can provide nutrients that can last twice the life-span of soils that do not contain any earthworms. By starting seedlings on vermicompost instead of transplanting them, the chances of germination occurring increases. In a February 2000 study, researchers measured the effects of vermicompost and compost on plant growth with results indicating that there are improvements using vermicompost, but the amount of improvement depends on the nutrient content (Atiyeh 2000). This is comparable to a child drinking milk, we know that the child will receive calcium to help with strengthening bones, but we do not know how much calcium the child is actually absorbing.

Organic Soil Solutions. http://organicsoilsolutions.com/education-center/the-world-beneath-our-feet/

Our Study: Worms vs. Fertilizer

In our study, we wanted to see whether placing worms in planters would yield more growth in pea plants than fertilizer would. After three weeks of collecting data we weren’t able to get a significant difference in the change in growth for the two treatments; however, we did see that planters that had worms in them grew the tallest and the fastest and the planter with the fertilizer treatment produced the highest number of plants. This could mean that using worms instead of fertilizer in small scale systems like home gardens, could be the better option and fertilizer would be the better option for a more grand scale option. 

In conclusion worms can be a real force to be reckoned with when it comes to helping out plants to grow big and strong. Next time you decide you want to plant a nice garden in your backyard, go pick up some earthworms instead of fertilizer to use on your crops!

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References: 

Atiyeh, R.M., S. Subler, C.A. Edwards, G. Bachman, J.D. Metzger, W. Shuster. 2000. Effects of vermicomposts and composts on plant growth in horticultural container media and soil. Pedobiologia 44:579-590.

Drake, H.L., M.A. Horn. 2007. As the Worm Turns: The Earthworm Gut as a Transient Habitat for Soil Microbial Biomes. Annual Reviews of Microbiology 61:169-189.

Zaller, J.G. 2006. Foliar Spraying of Vermicompost Extracts: Effects on Fruit Quality and Indications of Late-Blight Suppression of Field-Grown Tomatoes. Taylor & Francis Online 24:165-180.