Rototilling, cultivating or even walking on wet soil destroys its structure. Yes spring is here, but frequent rains are keeping our gardens wet. There is a tendency for many beginning gardeners to spade or till when soils are sometimes muddy. But when wet soils are disturbed, the soil’s structure is destroyed, and it then dries with large, hard lumps.
You will also destroy the soil’s structure if you work it when it is bone dry.
The proper time to work the soil is when it is at what is known as field capacity and slightly drier. Wait to spade or till until you can squeeze a handful of the soil into a ball that crumbles lightly when you open your hand.
Silt and clay soils are more prone to be damaged than sandy soils. This is because sandy soils drain more readily, and silt and clay soils retain more water. Silt and clay soils that are rich in organic matter drain more rapidly than silt or clay soils void of organic matter.
If you have been rototilling or spading your garden year after year at the same depth, you have most likely created a plow-pan. A plow-pan is simply a layer of compressed soil beneath the plowed, rototilled or spaded zone. This is a common problem in agriculture where fields have been plowed year after year at the same depth. The tines of the rototiller and tip of your spade or shovel work like a plough to compress a layer of soil not easily penetrated by roots or water.
You can determine if your garden has a plow-pan by pressing a broom stick or a piece of half- to three-quarters-inch pipe into the soil. If the stick or pipe can easily be pushed into the ground five to six inches and no farther, you know you have a plow-pan. If you can push the stick or pipe 10 to 12 inches, you do not have a problem.
In a small garden, a plow-pan can be destroyed by double digging. Double digging means you dig out a shovel of garden soil and, using the same spade or shovel, dig deeper in the same hole and remove another shovel of soil. The second removal will be the plow-pan. In a large garden that can accommodate a tractor, the plow-pan can be destroyed with an attachment called a sub-soiler, which works best when the soil is as dry as possible.