28 SportsTurf | February 2013 www.sportsturfonline.com

FieldScience | By Joey Fitzgerald

HOW CAN EARTHWORMSBE BENEFICIAL TO US ASTURF MANAGERS? Weknow of the natural aerification

that takes place from earthworm activity inthe soil, ultimately opening up pore spacefor root growth and improving water andoxygen movement, but is there any otherway that we can benefit from these slimycreatures? It turns out that through aprocess called vermicomposting we can po-tentially reap countless advantages in mak-

ing turfgrass more stress tolerant while im-proving soil structure while reducing de-pendence on chemical and pesticide use.

Vermicomposting is an organic processused to convert agricultural and other wasteinto valuable living soil amendments. Theend result of the vermicomposting process isthe production of earthworm excrement, re-ferred to as castings. These castings arepacked with beneficial nematodes, protozoa,fungi, organic matter, plant growth regula-tors (humates and fulvates), plant growth

hormones (IAA and gibberellins), and solu-ble nutrients (N, P, K, Ca, and Mg).

SOIL NEEDS ORGANICMATTER AND MICROBES

To fully understand the benefits ofworm castings, it is best to first compre-hend the need for sufficient organic matterand healthy microbial activity in the soil.Organic matter serves as a storehouse fornutrients in the soil. Unlike soluble syn-thetic fertilizers, the nutrients stored in or-ganic matter and microbial bodies do noteasily leach out. The organic matter formsaggregates with fungus and other beneficialbacteria making it difficult for nutrientleaching from heavy water movementthrough the soil profile.

The diverse addition of microbial life tothe plant’s leaf surface and rootzone hasmany benefits, but perhaps the greatestand most direct benefit comes as a popula-tion addition to the soil food web. Thisaddition helps to maximize a continualcycle of breaking down and releasing nu-trients into plant-available forms accessibleto the roots. As bacteria and fungi feed onorganic matter in the soil, they store nutri-ents within their body while releasing oth-ers. Then as nematodes and protozoa inturn prey on them, nutrients are releasedfrom the bacterial and fungal bodies intothe soil in a plant available-form ready for

Organic matter serves as a storehouse for nutrients in the soil.

Use earthworm castingstea for better turf

>> THE BEGINNING of the brewing process—thestraining bag of worm castings is placed in water.

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root uptake. When organic matter is fed tothe soil, the microbial life then feeds nutri-ents to the plant.

BENEFITS OF WORM CASTINGSNutrient Cycling and Retention: As

mentioned earlier, aggregates formed frommicroorganisms within the soil greatly re-duce nutrient loss, ultimately reducinggroundwater contamination. Less nutrientleaching, coupled with a healthy microbialpopulation unlocking nutrients already inthe soil, leads to a lessened need for thequantity of fertilizer output.

Microbial Diversity: The addition of anincredibly diverse population of microor-ganisms from the worm castings helps max-imize the productivity of the soil food web.

Water Retention: As the amount of or-ganic matter within the soil increases, so toodoes the water holding capacity of that soil.

Disease Suppression: Spraying wormcastings tea populates the soil and leaf sur-face with an exorbitant amount of microbesall searching for a food source to survive.

This diversity ensures that all of the organ-isms have a predator in the soil; because ofthis, no one organism can easily reach pop-ulations high enough to cause damage ofany significance. Working symbioticallywith the plant’s roots system in this wayhelps to eliminate harmful molds and fungifrom inoculating the plant’s surface.

Worm castings don’t do miracles againstall plant disease; however, research com-

pleted by Dr. Norman Arancon and Dr.Clive Edwards at Ohio State has shownthat worm castings suppress Pythium ulti-mum and Rhizoctonia solani diseases. Fur-ther research conducted by the PlantSciences Department at Cornell Universityshows that the beneficial microbes colonizeseed surfaces masking the chemical signal-ing needed for the pathogen to locate thehost material.

>> LEFT: The middle of the brewing process. The foam indicates good microbial activity in the tea. >> RIGHT: This is the finished solution with a tea bag in the foreground.

Insect Control: Worm castings are richin chitinase, a chemical that decomposesthe exoskeleton of insects. Many researchersbelieve that its presence in the castingsprove inhibitory to many damage-causinginsects.

Plant Available Nutrients: Worm cast-ings provide soluble nutrients to the plant.The nutritional analysis can vary dependingon the food source during the vermicom-posting process, but generally the castingshave around 1-3% N, .5-1% P, and 1-2%K. These levels are low, but they are imme-diately ready for plant uptake.

APPLICATION PROCESSWorm castings can be applied a couple

of different ways. Like any compost, thecastings can be spread in a finely ground,dry formulation. Dry application would bemore useful in a situation when it could be

added directly to the soil profile during arenovation or construction.

When applied to the plant, the best andmost cost effective application method is bymaking a tea from the castings. Much likemaking a pot of tea at home, the concept ofthis tea is to simply use water to extract allof the “good stuff ” from the worm castingsinto a liquid solution that can easily be ap-plied. This process can be done two differ-ent ways: extracted or aerobically brewed.Aerobically brewed teas require more timeto produce, but the end product is a solu-tion with exponentially higher microbialpopulations than that of extracted teas.

This aerobic tea brewing process is fairlysimple, but it does require some time, at-tention, and know how. A variety of brew-ing containers and methods are availableand can be used; however, a key point tokeep in mind when producing the castingstea is that because the tea is a living solu-tion, oxygen and a food source must becontinually available to the microorganismsin the tea for survival and maximum popu-lation growth.

During the STMA Conference last yearin Long Beach, CA I sat in on an educa-tional program presented by Leif Dickinsonabout his practices with growth regulatorson his bermudagrass at Del Mar Thorough-bred Club. During the presentation hementioned his use of worm castings tea

brewed with alfalfa to jump start his turfout of large patch symptoms in the springtime. Our field had experienced large patchthe previous fall, so this concept caught myattention. I began looking for any addi-tional information or research anywhereabout the benefits or drawbacks from theusage of worm castings tea on turfgrass.What I found was a wealth of success storiesfrom gardeners, crop producers, and thegreenhouse production industry, but noth-ing more documenting real success on turf-grass. After reading all of the different usesand benefits, I came to the realization thatonce you strip everything down, growingquality turfgrass isn’t really that much dif-ferent from growing other crops, so I de-cided to give brewing an aerobic castingstea a try.

For the brewing system I retrofitted anair bubbling system off of a 10-gallon aircompressor we had sitting around. Webegan spraying in mid-March as ourbermudagrass had begun coming out ofdormancy. My intention was to make threeapplications on 2-week intervals with mylast application coming in mid-April; in-stead I got hooked on the results we werehaving and continued spraying on the bi-monthly interval schedule for the remainderof the growing season.

OBSERVATIONS FROM TRIALAND ERROR APPROACH

• Because our field displayed the visualsymptoms of large patch in the fall, I natu-rally anticipated those same areas to appearas the field broke dormancy in the spring.When the turf woke up from the winter,the infected areas from the previous fallwhere nowhere to be found.

• I was amazed how well the “usual sus-pect” wear areas handled traffic throughoutthe year. Even before the bermudagrass sea-son really kicks into gear, the turf dealt withour 18 high school game, pre-Lookouts sea-son slate with ease. From my observation,this improved wear tolerance continuedthroughout the 2012 season.

• Even though we had a substantiallydrier summer, two different observations Imade this year can speak to improved waterretention in our soil. First, we did not havean occurrence of fairy ring, which the fieldhad experienced the previous six seasons.

30 SportsTurf | February 2013 www.sportsturfonline.com

FieldScience

>> THIS IS OUR BREWING SET-UP with the air compressor in the middle of the four containers andPVC piping branching off of that.

>> CLOSE-UP view of the dry worm castings.

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Our fairy ring symptoms are the result ofthe inability of water to penetrate throughthe hydrophobic tendencies of the thatchlayer, ultimately resulting in a plant thirstyfor water. Secondly, we dodged having tobabysit any dry spots resulting from our de-ficient irrigation system.

These are only the observations over thecourse of the 2012 growing season whencompared to the previous season. Are theseresults an anomaly or were they because of atweak in our cultural and fertility manage-ment? I would be naïve to think that theseresults can be only be attributed to the ad-dition of the worm castings tea, but I dobelieve when coupled with good manage-ment practices, positive results will follow.

WHERE TO GO FROM HEREThe idea of turfgrass benefiting from ver-

micompost is a relatively new concept.Much additional education and research isneeded about the functionality of the addi-tion of these microorganisms from theworm castings to the soil; however, our re-

sults over the past season indicate that thereis a place for castings tea in environmentallyfriendly turfgrass management practices.Whether it be reducing synthetic fertilizer,pesticides, groundwater contamination,water use, etc., it is becoming difficult to es-cape ever-growing environmental concernsand restrictions. Because of this, any prod-

uct or concept that can assist in limitingnegative environmental impacts while work-ing in conjunction with our daily manage-ment practices should be explored. ■

Joey Fitzgerald is the head groundskeeperfor the Chattanooga Lookouts.

>> BEFORE A GAME on August 14, 2012.