Karen Neill is a horticulture extension agent.

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Turn & Burn | How to use a 3-bin compost system
by Karen Neill       #Fertilizing   #How to   #Sustainability and Self-Sufficiency

Along with the increased interest in sustainable living and gardening, composting is also regaining popularity. It’s a great way to manage organic matter while creating a valuable resource at the same time. There are many different methods of composting but the key elements they share are the organic materials that go in them: water, oxygen, and the microorganisms that actually do the decomposing.      

My favorite type of composting is the three-bin method. This system works well if you have the room and generates a lot of organic matter. With this system, you will have different piles in various stages of “ripeness”: fresh organic matter in one bin; then moved to the second bin when the first is full and the compost is ready to turn; then repeat, turning compost into the third bin, where it finishes.     

You can make your own three-bin composting unit out of many different materials. Old pallets wired together are the least expensive, but wire and wood, wood slats, or even cinder blocks can be used to construct the unit. If using the wire and wood or the wooden slats, you will need some basic carpentry skills and tools. Each bin should be roughly 3 feet tall, wide, and deep. I am partial to those that allow air to easily circulate around the pile. All that oxygen keeps the microorganisms in the soil happy and working hard to break down your organic matter.      

 

The first bin is where the fresh organic matter is placed. Place “green” materials like grass clippings or other fresh plant waste with “brown” materials like dried leaves, wood chips, or shredded branches. Green material tends to be high in nitrogen; brown material contains more carbon. If green waste is limited, you can add nitrogen-containing fertilizer to bring the carbon and nitrogen ratio closer to 30/1. If using kitchen scraps, dig a hole in the center of the pile and bury to comply with many city nuisance ordinances (you would hate for a neighbor to complain). A thin layer of garden soil should be applied to introduce the microorganisms that do the composting. Be sure to keep the pile moist. An easy way to tell if your pile has enough moisture is to squeeze a few handfuls of materials. Everything should feel damp, like a wrung-out sponge. If it doesn’t, it’s time to add water. Turn your pile while adding water so everything gets moist. If more than a drop or two of water comes out when squeezed, then your pile is too wet and turning is in order so you can balance moisture and air levels, optimizing conditions for decomposition.      

As the pile starts to shrink, you will know that it’s decomposing. It is a good idea to check the temperature of the compost from time to time, ideally with a compost thermometer. Once the temperature starts to drop, it is time to turn. Make sure that the outside, and undigested stuff, gets put into the center. After the middle has reached 140-150 F, turn the pile from the original bin into the adjacent center bin.     

Once the second pile is filled, allow this to further decompose, again watching the value decrease. Follow the same steps and transfer to the third bin. While this last bin will still go through some decomposition, it is ready to use at any time the need arises. I find this type of composting super easy to set up and easy to “work.”

 

 

 

      

A version of this article appeared Carolina Gardener Volume 28 Number 1.
Photography courtesy of Arina P Habich/Shutterstock.com, Cindy Shapton, and Tim Matthews.
      

 

 

Posted: 06/03/16   RSS | Print

 

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