|Written by Jeff Poppen|
|Tuesday, June 26, 2012|
If you love digging in your garden, you’ll have twice as much fun double-digging.
When we dig into the earth, a change n color and texture can be noticed. Somewhere between six inches and a foot deep, the top soil ends and the subsoil begins. Topsoil is darker, looser and where the life is. The subsoil is lighter in color, an heavier in texture and lifeless.
Imagine your garden with eight inches of top soil and all of the plant roots living there. Then imagine it twice as deep. It’s like having a garden twice as big for the roots, and the plants will respond accordingly. Double digging is an old time method of deepening garden soil.
First, a shovelful of soil is removed from one side of the garden bed. It can be out to the side or in a wheelbarrow. We’ll dig until we hit the subsoil.
Now we break up the subsoil with a digging fork and pick. It feels good to open up this tight ground so our roots can penetrate easily. A root can’t get in here, it’s as hard as cement. We want to incorporate air and loosen her up.
Tennessee subsoil is often acidic so a sprinkling of lime will help to encourage root activity. I swing the back of the fork on the clods to further break them up.
The next step is to scoot over and move the adjacent topsoil onto the freshly dug trench. Once it’s over there, pick up the pick again and work up the lower layer. We want to leave the subsoil where it is, but really fluff it up. Roots need oxygen, and by double digging they can utilize twice as much area in the soil. If allowed to, many plants will send the roots down several feet. Think of all the extra nutrients and moisture they can get.
The last trench gets filled with the soil from the first one. The bed will be slightly higher than ground level because of the new air spaces. Don’t walk on it. Squishing it down defeats the purpose. Make the bed narrow enough, five feet or less, to be able to reach easily into the middle.
I was a back yard gardener long ago, and double dug the beds. Now, as a farmer, I employ a tool to break up the hardpan created by plowing. A sub-soiler is a two-foot long
Shank with a shoe on it. it is pulled through the fields, but only when it is dry. Wet clay will smear and seal back up. I usually do it in August, after a crop is removed and before the cover crops are sown.
The first time a bed is double dug will require the most work. Next year it will be easier. Keep the soil loose up to your elbows and you’ll soon be up to your elbows in vegetables.