Is it bad to put logs in the bottom of a raised bed?

Are logs bad for raised beds? Recently there’s been talk of how this popular method for filling tall raised beds might not be all it’s cracked up to be.

But why? Well, there is a phenomenon called nitrogen immobilization. The simple explanation of why this happens is because adding a ton of wood or wood chips into a soil mixture will result in a fungally dominant soil food web, which will pull nitrogen from the soil immediately surrounding the wood to help break the wood down, thus robbing it from your plants.

While this is TRUE, there are a few considerations:

1. Most gardeners bury logs deep enough in their beds that the root systems of plants grown above in the soil mix rarely make it to the log layer

2. The nitrogen is only pulled from the soil directly surrounding the wood

3. The scale of nitrogen immobilization relative to causing a true plant deficiency is minimal

in the end, we still highly recommend this method, as it saves 50 to 60% or more on soil cost, and is a great way to repurpose organic material.