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This week’s Book of the Week feature is Albrecht on Soil Balancing, Vol. VII, by William A. Albrecht.
Chapter 7: The Use of Mulches
In considering the use of mulches in gardening, it is necessary — at the outset — to define the word “mulch.” Let us agree that a mulch is a particular arrangement of, or addition to, the surface of the soil to stimulate, or to provide, a cover.
According to this definition, then, a mulch may be made, either by Nature or by man from the upper or surface portion of the soil itself. It may also be the result of applying on the soil some cover consisting usually of organic materials, particularly plant residues.
When a soil has been watered generously by rain and when the drying of its surface starts, it is by that rapid surface drying that Nature herself makes a soil mulch. In some cases, this is a soil crust of one or two inches of depth. In others it is a granular, non-crusting cover. Both of these dried soil layers are mulches to help to reduce evaporative loss of water up through them.
While the crust mulch functions to cut down water loss by evaporation, it fails in the second function of the mulch-soil-water relations: namely, it does not facilitate ready entrance of the rain water into the soil. Aiding infiltration of the rain is the really significant function of the mulch or the soil cover in relation to water. For this function alone, the breaking of the soil crust and the mechanical maintenance of the granular mulch are well considered practices.
The use of a straw, leaves, sawdust, and other organic materials as mulch is a well-known and good gardening practice. The use of these mulch materials assumes that the soil under them has been brought up in its fertility level to the point of discounting any possible disastrous effects by microbial competition with the crops for the nutrients in the soil’s supply.
It is around this simple principle, that the wisdom of the use of the mulch turns for failure or success.
More recently there have become available mineral materials, of very little weight per unit volume which serve as mulches, particularly in potted plantings. The most prominent of these, known by various commercial names, are the expanded micaceous materials. Almost completely inert chemically, as they are — save for possibly the contribution of some potassium — they are long-lasting and bring about an open structure when incorporated into the soil. This effect is particularly advantageous on soil of more clayey nature. Such soils are benefited highly by the mulches in preventing crusting and cracking and then still more by the successive incorporations of these flakey mineral materials into the body of the soil itself. This repeated incorporation brings on the improved granular condition for self-mulching, so much desired.
That the mulch might be a by-product of the crop itself or that extra fertility might be added to the soil for growing one crop that is to be the mulch for another, is a newer concept in the use of mulches.
While the soils in the Midwestern United States form a granular mulch naturally under sparse grass vegetation, nature has been applying an organic matter mulch in the form of either heavy prairie grasses or forest leaves and litter on the more humid soils in the Eastern United States.
Here is Nature’s suggestion that the degree of development of the soil, according to the differing degrees of weathering under the climatic forces with the resulting different levels of soil fertility, points out the mulching procedure that would be wise. If the soils of the Eastern United States are to be self-mulching by their own granulation in place of requiring applied mulches, then they must be brought up in their fertility to the level duplicating that of the soils in the Midwestern States.
Only by building up the organic matter and the fertility contents in the more highly weathered humid soils will they become granular and mulch themselves effectively. With the naturally more granular Midwestern soils, the high fertility and the organic matter contents make each unit of rainfall more effective.
Mulching artificially seems to have come into vogue because the soils were less fertile. But the emphasis went to the water rather than to the creative power of the soil. If such is the case then, by reasoning conversely and building up of the soil fertility to enable the soil to grow into itself more organic matter, the need for extra mulching should be less or the extra mulching should be so much more effective.
Nature’s climatic patterns of the soil are giving their suggestions by which we can make better use of mulches. Our soil will find itself undergoing conservation much more extensively and will be used more efficiently when we see nature’s pattern of natural mulching with its benefits according to the levels of soil fertility concerned.
Mulching alone, as a mechanical ministration, cannot offset completely the shortage of fertility in the soil. Conversely, however, building up the fertility can be all the more reason for mulching also, a combination with doubled benefits because of the more efficient use of both the soil and the mulch that covers it.
About the Author:
Dr. William A. Albrecht, the author of these papers, was chairman of the Department of Soils at the University of Missouri College of Agriculture, where he had been a member of the staff for 43 years. He held four degrees from the University of Illinois. During a vivid and crowded career, he traveled widely and studied soils in the United States, Great Britain, on the European continent, and in Australia. Born on a farm in central Illinois in an area of highly fertile soil typical of the cornbelt and educated in his native state, Dr. Albrecht grew up with an intense interest in the soil and all things agricultural. Both as a writer and speaker, Dr. Albrecht served tirelessly as an interpreter of scientific truth to inquiring minds and persistently stressed the basic importance of understanding and working with nature by applying the natural method to all farming, crop production, livestock raising and soil improvement. He always had a specific focus on the effect of soil characteristics upon the mineral composition of plants and the effect of the mineral composition of plants on animal nutrition and subsequent human health. Respected and recognized by scientists and agricultural leaders from around the world, Dr. Albrecht retired in 1959 and passed from the scene in May 1974 as his 86th birthday approached.
More By This Author:
Albrecht Papers Vol. 1-8 + Video, by Dr. William A. Albrecht
Albrecht’s Foundational Concepts, Vol. I, by Dr. William A. Albrecht
Check out the Albrecht collection for a full list of all his titles.
Titles of Similar Interest:
The Biological Farmer, Second Edition, by Gary F. Zimmer & Leilani Zimmer-Durand
Hands-On Agronomy, by Neal Kinsey & Charles Walters
Humusphere, by Herwig Pommeresche