Outdoor Services Crew

Wednesday, February 23, 2011

Compost Tea

Over the next couple of weeks I will be introducing you to our new Compost Tea Brewing systems. Since I have been at the University, I have been adding fish emulsion, seaweed extract and a wetting agent into the soil. These products are inputs I have made to help with existing microbial life by increasing their numbers which in turn provide many benefits to the soil profile. Some of the major benefits include increased breakdown of organic materials, the release of natural forms of nutrients, which become plant available and help to cut down the need for synthetic fertilizer applications.

One of the most intriguing aspects of compost tea brewing is the large amounts of beneficial micro-organisms that are added to the soil. The process begins with compost being put into a small "tea bag" which is then placed in an oxygen rich tank of water and allowed to brew for up to 36 hours, depending on the temperature of the water. During the brewing process existing micro-organisms in the compost are freed from the compost and become loose in the water and free to float around. During this time a "food" is introduced into the water which provides nutrients for the micro-organisms and thus allows them to reproduce at a high rate. As long as there is food, large amounts of dissolved oxygen, and warm temps, the organisms will prolifically reproduce creating a "tea" of micro-organisms.

Once the brew cycle is finished, this "tea" will be applied to the entire campus landscape. The normal method of application is through backpack sprayers or spray tanks which drive across landscape to apply the product. This method is not viable here at CU-Boulder. We have too many small areas and pedestrian traffic, which would make it very impractical to drive around every inch of landscape to apply this product. Not to mention the time and cost of trying to make such an application happen. So, we are going to try something new, we are going to inject it through our fertigation system. This is a system which injects the product directly into the mainline and allows the existing irrigation infrastructure to make the application for us.

There are challenges to this method, such as if the organisms will survive the "ride" through the pipes and make it through the sprinkler heads and safely onto the landscape. Working with our Compost Tea company, we believe we will only be looking at a mortality of 3-7 percent. Which initially seems like a lot; however, when you consider we will be introducing literally billions of organisms, this seems to be an acceptable loss. The other challenge is quantifying the amount needed to cover the acreage we have here on campus. Again working with our chosen company we have made the necessary calculations and have determined what is needed.

The amounts are large for each delivery system: at our 28th Street pump station we will need to put out 750 gallons of product during an 8 hour water window and at our Varsity pump station we will need to put out 500 gallons. This quantity will provide the proper application to the entire main campus landscape. There are many parts to creating this system and we have received all of our componants and are begining the installation!

I'm really looking forward to using a new technique which hopefully will provide a better growing medium for our landscape.