Turning over soil, often called digging or tilling, is the process of loosening the earth within a designated garden space. This action helps prepare the ground for planting, allowing roots to establish easily. For a new or heavily compacted garden bed, this preparation involves deep inversion of the soil layers, while established beds might only require shallow aeration. This instruction provides guidance on the traditional method of deep soil turning.
Rationale and Timing for Soil Turning
Gardeners turn soil primarily to address compaction, which restricts the movement of air, water, and roots. Loosening the earth increases aeration, ensuring roots access oxygen and allowing water to penetrate the surface. This process also provides an opportunity to uniformly blend organic matter and soil amendments, such as compost or manure, throughout the root zone.
The timing of this work is important, typically occurring in the early spring once the worst of the winter rain has passed, or in the late fall to allow organic matter to decompose. To determine if the soil is ready, pick up a handful of earth and squeeze it firmly. If the soil remains a muddy, cohesive ball, it is too wet to work, as digging wet soil destroys its structure and causes severe clumping. The soil is ready when it is moist enough to hold its shape temporarily but crumbles easily, indicating a workable condition.
Choosing the Right Tools and Preparation
Selecting the correct tools makes the process of turning soil more efficient. A garden spade, with its flat, sharp blade, is best suited for cutting into the soil and cleanly lifting and inverting large sections of earth. A digging fork is superior for penetrating dense, stony, or heavy clay soils, as its tines require less effort than a solid spade blade. A broadfork, a specialized tool with long tines and two handles, is used for deep aeration without inverting the soil layers.
Before any digging begins, the designated bed area must be completely cleared of surface debris, including large stones, old plant stalks, and weeds. Mark the perimeter of the garden bed with stakes and string to clearly define the working area. Removing established weeds, especially perennials, beforehand prevents their root fragments from being distributed throughout the newly turned soil, which could lead to increased weed growth.
Step-by-Step Technique for Manual Soil Turning
The most thorough manual method is the trenching or double-digging technique, which loosens the soil to a depth of 16 to 24 inches. Begin by using the spade to dig a trench across one end of the bed, creating a strip about 12 inches wide and the depth of the spade blade, which is typically 8 to 10 inches. The soil removed from this initial trench must be temporarily placed outside the bed on a tarp or in a wheelbarrow, as it will be used to fill the final trench.
Once the first trench is empty, use the digging fork to loosen the subsoil at the bottom. Plunge the tines in as deep as possible and rock the tool to break up the lower layer. This action loosens the second 8 to 10 inches of earth without inverting it, which helps preserve the beneficial soil structure of the subsoil. At this stage, incorporate any deep-acting amendments, such as well-rotted compost or manure, into this loosened subsoil layer using the fork.
Next, move to the adjacent 12-inch strip of unworked soil and dig a second trench. Flip the topsoil from this section directly into the empty space of the first, pre-forked trench. As you work backwards across the bed, the soil from each new trench fills the previously emptied and loosened trench, gradually moving the topsoil forward. Use the spade with a straight back and bent knees, utilizing the foot plate to drive the blade into the ground, reducing strain.
Repeat the process of digging, flipping, and forking the subsoil until the entire bed has been turned over. A final empty trench will remain at the opposite end. Use the soil originally removed from the very first trench to fill this final trench, completing the inversion. Finally, use the back of a rake or the flat of the spade to lightly tap and level the freshly turned earth. This settles the soil and breaks down large clods, ensuring a smooth, aerated surface ready for planting.
Alternatives to Traditional Digging
While deep digging is effective for breaking new ground or alleviating severe compaction, some modern gardening practices favor less soil disturbance.
Shallow Cultivation
Shallow cultivation involves only working the top few inches of soil, often using a broadfork or a garden fork to gently lift and aerate the earth without mixing the distinct soil horizons. This method is less disruptive to the beneficial organisms that inhabit the upper soil layers.
No-Till Method
The no-till method represents the least disruptive alternative, completely avoiding deep soil turning. This practice focuses on building soil health by consistently adding layers of organic matter, such as wood chips, shredded leaves, and compost, directly onto the surface of the garden bed. Over time, earthworms and other soil organisms naturally incorporate this material, improving drainage and structure without manual inversion. This approach aims to mimic natural forest floor processes.