Preparing Garden Beds: Dig vs. No Dig
This post is meant to give a quick explanation of the differences between two basic methods of creating new garden beds (or as I prefer to say: mini-farming beds). The two basic choices in creating a new bed are "dig" versus "no-dig". I have read books and watched videos by proponents of both methods with each side claiming that their method results in higher yields. I am not going to express an opinion on which method is better, I am simply going to try to explain each method so that if you read other articles or watch other videos, you will have a better appreciation of what the proponents of each method are talking about.
First let's discuss "digging" methods of creating a bed. Obviously the idea here is that you are going to get a shovel and dig something. Even within the "dig" method there is the choice of single digging and double digging.
Single digging involves turning over the soil in a new bed to the depth of one garden spade. First you identify the outline of your new bed (let's say with string) and then you dig the length of the bed and dig out a shovel's width and depth of soil, creating a trench. You put that soil in a wheelbarrow. Then you move to the next row (at the edge of the trench that you just dug). You dig out the width of a spade, but instead of placing that soil in the wheelbarrow, you place it (overturned) in the trench that you previously dug. You are thus turning the subsoil from the new trench into the topsoil of the previous trench. You keep moving to the left (or right) until you have overturned the entire length and width of the bed. When you get to the furthest end of your bed, you take the soil in the wheelbarrow from the first row and place it, overturned, into that final trench.
Double digging is really the exact same process as single digging, except that when you dig out each trench, you take a digging fork and further loosen the soil at the bottom of each trench. You don't have to remove the soil at the bottom of the trench, you simply work the fork in to break up and loosen soil that may have been compacted before putting in new soil. Thus you are in essence loosing up a two spade depth of soil or "double" digging.
The No Dig method should be fairly obvious, you don't dig into the soil at all. You simply use some type of covering (mulch) to kill any existing grasses or weeds on the spot that will become your bed. After a sufficient period of weed and grass kill-off, you should have a relatively pristine area of top soil to work to create your garden bed.
As I said, I am not going to express an opinion on what is best because I do not have an opinion. The idea behind digging is that the area of soil that you will be gardening may have been compacted over a period of time. By loosening the soil, you allow more aeration of the soil for roots. You can also take the opportunity of the dig to change your soil. For example, if you have very hard clay in the area that you will be growing, you can mix in acquired sand to loosen up the soil while you do the digging. The idea behind No Dig is basically that there is an entire ecosystem (soil microbiome) underneath topsoil. There are fungi that live symbiotically with plant roots and that help plant roots to acquire nutrients from the soil. By overturning the soil, you are disrupting the soil microbiome and the area will not be well-productive until the microbiome is restored. Obviously, the No Dig method is also easier because digging can be back-breaking labor.