Agroforestry Word of the Week - May 27, 2020 - Double Digging

Double Digging -/dəb(ə)l, digging/ - verb

May 27, 2020

 

Definition: The process of separately digging up the topsoil and subsoil layers of a cultivated space to improve soil fertility and aeration. This involves adding and mixing soil amendments at what will ultimately be the root level.


Why should you double dig?
Double digging allows farmers to increase the productivity of their permagardens. By double digging, adding soil amendments to vegetable beds, and using triangular spacing, farmers can also increase the number of plants per square meter. 

Tools Needed for Double Digging:

1. A spade or other digging tool

2. Four shovels full of compost or manure per square meter

3. One shovel full of charcoal powder per square meter

4. One shovel full of plastic-free wood ash per square meter

The Forest Garden Training Center's Technical Manual digs into the process of double digging. 

Read through chapter 13 to learn more about each step. 
 

Soil Amendments for Double Digging

 
  • Wood ash is a soil pH stabilizer that is rich in potassium and phosphorus. Wood ash should be sourced from a pure wood fire, free of plastic, to avoid harmful toxins.
  • Eggshells are high in calcium and very beneficial to crops in the cabbage family. Eggshells can be pounded into a fine powder before being added directly to the soil or in a compost pile. 
  • Coffee grounds are an excellent source of organic nitrogen and can be added to compost or mixed directly into the soil during the double-digging process. 

 

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