OakOpen News

Soil Structure

The soil structure, or tilth, refers to the way in which all the particles of clay, sand, humus and silt all clump together into crumbs or granules. If you dig up a spadeful of moist loam and drop it onto a hard surface, you will be able to see how it comes apart. If it comes apart in porous crumbs that are about a half inch in diameter, this means it will retain moisture; and the air spaces will allow water to drain, this is all considered to be good soil structure.

If the soil breaks into cube like clods that have flat surfaces and sharp corners, it is too heavily compacted and you will have to use a lot more man power to make it work. The soil structure of this soil will not retain moisture nor will it be able to drain.

You can let nature take care of all this but it will take a long. You can grow cover corps of grass year after year. The roots of the grasses will break up the compacted soil, and the foliage will protect the surface from heavy rains. The grass itself will decompose into humus. Microorganisms in the soil will break the organic matter down to usable nutrients.

]]>

For much quicker results, in the fall mix into the soil a 2- to 4-inch thick coating of dehydrated manure, compost, peat moss, or similar organic material, but you will have to double dig if the subsoil is extremely heavy. You should do this again in the spring, as soon as the soil is not too wet to work.

An excellent soil remediation would be organic material, which is derived from animals and plants, called humus, breaks down in the soil, and is a dark, gummy substance. Not only is humus rich in nutrients but it is also the agent by which faulty soil structure is best remedied. Humus binds sand particles together in light soil, and in heavy soil it will keep clay particles apart, allowing needed room for air and water. Soil that contains a large amount of humus is termed “rich,” and if there is just a little humus the soil is considered to be “lean.”

Any bulky organic wastes, such as animal manure, fallen leaves, grass clippings, kitchen scraps, or sawdust, are useful as sources of humus. It is important to remember, however, that these wastes should be partly decomposed before they get added to the soil; Nutrients are not readily available to plants until they have been altered by decomposition. Furthermore, the microorganisms that causes the decay use up a great portion of nitrogen in the first stages decomposition; so the addition of fresh organic waste can cause short-term nitrogen deficiency in the soil. For this reason it is a good idea to mix a little fertilizer, which is nitrogen-rich, to help feed the various agents of decay if you happen to use bark chips, sawdust, or a similar organic material as a summer mulch.

Humus-forming materials, such as leaf mold, peat moss, or well-rotted manure, can be obtained in ready-to-use form from any garden supply center or garden nursery. Better yet, you can process your own by composting. Either way, you should work large quantities well into the soil. An excellent application is a 6-inch layer of loose organic material which you work into the soil to a depth of at about 12 inches. By doing all this you should be able to have a soil structure that is considered to “rich.”