The Secrets of Compost Tea

Michael Almstead, August 9, 2012. 

The Compost Tea Workshop was held on the beautiful 

campus of Rye Country Day School.

Last month, Almstead had the opportunity to conduct a workshop on Compost Tea and Air Spading for the Northeast Organic Farming Association (NOFA). Arborist Dan Dalton and I, along with compost tea brewing specialist Russell Wagner and lawn technician Marc San Phillipo and several other Almstead professionals, really enjoyed being able to share our knowledge and experience with others interested in organic tree and plant care.

The workshop was intensive. We covered both the science behind Compost Tea brewing and the practical issues and hurdles to creating a brewing business. I’ve been involved in Almstead’s evolution into organic care from the beginning and believe that products like compost tea are win-win: healthier for the lawns and trees as well as the environment, friendlier to consumers, and safer for everyone.

Continual aeration is a necessity for compost tea.

Brewing high-quality compost tea is an involved, scientific and careful process. Compost tea is NOT a slurry of compost and water. It must be carefully balanced to meet the nutritional requirements of the plants it’s meant for.  It contains living organisms that have to be kept alive through constant aeration – both while the tea is brewing and in the truck delivering it.

Russell Wagner microscopically checks our Compost Tea

 for the proper microorganisms and fungi.

We have a mini science lab in our Compost Tea brewing facility, where we examine everything going into the tea. We want it loaded with beneficial organisms, both bacteria and fungi; we add them, and make sure they are live and happy (and in the proper proportions) in the tea before we apply it. We also make sure that no damaging organisms are sneaking into our mixture.  This quality control is vital to brewing compost tea – without it, you’d  just be delivering a truckload of dirty water.

We have a rather substantial Compost Tea brewing operation here at Almstead. Compost tea is an organic way of adding nutrients and microorganisms to the soil – sort of a jump-start for soil to rejuvenate itself, making it more attractive for worms and other beneficial organisms, and keeping the process of soil development going. And it dramatically cuts down the use of chemicals, a plus for both for the environment and for people who are exposed to their lawns.

Dan Dalton describes the nutrient cycle.

Dan Dalton taught the segment on soil properties. He emphasized the necessity of understanding the chemical, physical and biological elements of soil in order to create a compost tea – sometimes augmented by other organic amendments – that facilitates the right soil profile. This goes way beyond simple pH – it includes factors such as adjusting the particle size of soil components and encouraging symbiotic fungi that help keep damaging organisms away from tree roots.

We create different teas for lawns and for trees because of their varying requirements. Lawns need a higher ratio of bacteria, while trees require more fungi. For large locations (like a college campus or business park) we can create a Compost Tea based on soil testing. Sometimes we add specialized ingredients like nematodes or mycorrhizal fungi to meet their specific needs.  We talked in general about recipes for compost teas – but the formulae that Almstead has carefully developed for our clients remains a closely-guarded company secret.

The participants examine fibrous roots exposed
by air spading.

Our NOFA presentation also included a demonstration of air spading. Air spading (using compressed air to loosen soil around tree roots) is a wonderful tool of organic tree care. There are several methods we can choose from, depending upon the results desired. Essentially, by using the air spade, we can loosen and/or remove compacted soil. We fill in with looser soil and amendments, allowing the tree roots to “breathe,” encouraging them to grow and giving them easier access to the nutrients and water in the soil.

Russell performed air spading on one of the Rye Country Day School campus trees. Since fibrous roots are concentrated in the top 8” of soil, compaction can deprive a tree of both oxygen and nutrients. First , he excavated the critical root zone around the trunk, easing soil compaction and allowing examination of the roots for signs of girdling or disease; then he air spaded out radially from the trunk (like slicing a pie).  These slices were filled with compost and other soil amendments to provide the roots with easy access to oxygen, water and nutrients.  

Marc San Phillipo demonstrates soil injection 

of compost tea into the root zone.

Mark San Phillipo also demonstrated the soil injection of compost tea into the root zone. Compost tea can also be used as a soil drench.

By the end of the day, the workshop participants seemed to leave with a new appreciation for these important tools in organic plant care.

-             --- Michael Almstead, Vice President & Arborist