Trench Compost

Trench compost video: Trench Composting in 60 Seconds

What is a trench compost?

Trench compost simply means burying compost material under a few inches of soil. After the initial labour, it is one of the lowest maintenance ways to compost.

What style does it fit?

Trench compost is one of the lowest-maintenance system available and so works well for both hands-off composters.

What space does it need?

Trench composting requires open garden space. Holes can be dug 6" or further from most plants, depending on root spread. Compost-sensitive plants may require slightly more room.

Does it work all year?

No, trench composting is only possible in the spring, summer, and fall.

How does it work?

Trench composting relies on naturally present bacteria, fungus, insects, and earthworms to consume the fresh organic material and transform it into humus, the organic component of healthy soil. The soil surrounding the material keeps it damp, supplies it with oxygen, and absorbs any smells. For that reason, trench compost doesn't need to balance nitrogen with carbon, and it also does not need to be stirred or watered. 

Start by finding a spot in the garden that is far enough away from established plants that you can dig without chopping their roots. Dig a hole or trench 12-18" deep. Put your compost material into the hole - almost any mix of food waste, grass, leaves, or other garden waste is fine, but avoid sawdust and woodchips as they may temporarily 'tie up' the nitrogen in the soil. Mix a small amount of soil directly into the compost material, then cover it with another 6-8" of soil. 

The finished compost cannot be moved, but the space around the trench will be fertilized from the buried material as it decomposes. Wait several weeks for the buried material to decompose before planting anything directly on top of it. (While decomposing, compost material can be a bit too acidic for delicate plants' roots.) The exception to this rule is squash plants like pumpkins or zucchinis, which grow well out of fresh organic waste, and therefore can be planted right away.  

***

Got more composting questions? Email the Compost Hotline at [email protected].