Double Digging Your Soil

Posted by Ena Clewes
December 14th, 2007
Filed in Soil and Fertilizer
Tags: dig, Soil and Fertilizer

Double digging, also called “trenching”: remove a spade’s depth of soil over all the area you want to improve and put it aside. Dig organic materials into the next spade’s depth. Mix the same organic materials into the soil you initially removed and put that mixture on top of the deeper mixture.

What you accomplish is aeration of your soil to a depth of  approx. 18 inches with the inclusion of organic matter, as well. Deep root penetration is easier, so that deep-rooted plants will reward you with better growth.

Admittedly this involves a lot of back- straining labor, however the value of this method for deeply-rooted perennial plants that grow in one place for several years, and for shrubs that are deep-rooted will be ongoing.

All you need for double digging is a spade or spading fork, perhaps a pick for the tough second layer, and endurance!

The majority of home gardeners will probably encounter a different soil situation:

Most soils have been plowed, disced, harrowed,spaded and forked for years so that there is no longer a sharp distinction between topsoil and subsoil. Another possibility is that the land may have been graded, leveled,
or cut-leaving topsoil and subsoil thoroughly mixed, or with topsoil removed entirely.

No matter how thick your topsoil layer is, you should aim to keep at least one spade’s depth in prime condition, crumbly, well aerated, and amply fortified with organic matter. You will know you have accomplished this when you are able to insert a spade for its full depth into your soil with almost no effort.

If you are preparing soil for annuals, vegetables, perennials or a lawn, it pays to think BIG in terms of organic matter quantity. Try to add an amount of organic material equal to 25-50 % of the amount of soil you are preparing. This means , that for the average spade’s depth bite of 8 or 9 inches you ideally should incorporate from 4 to 8 inches of organic additives.

Dig your soil to the depth of your spade, shovel or fork, then over the dug surface, spread the organic materials and dig them in. Spread about a 2- inch layer of organic additive and spade it in then repeat this process in 2 inch layers, until you have incorporated all the organic materials necessary.