Wallace's Comment:
"Although there are good reasons for composting, the idea can be
wrong much of the time. Since 75 percent, more or less, of the
organic carbon is lost in composting, little remains for real
improvement of the soil structure. When possible, direct application
avoids this problem. The value of organics for soil improvement
comes mainly from carbohydrates. Carbohydrates are mostly lost in
composting. Some users assume that the composting process results in
the production of biostimulants; uncomposted materials applied to
soil can result in the same."
From:
Wallace, Arthur and Garn A. Wallace. 1995. Compost and composting:
facts and myths. p. 39-51. Soil Conditioner and Amendment
Technologies, Volume 1. Wallace Laboratories, Los Angeles, CA.
335 pp.
Originally published in:
Wallace, A., Editor. 1994. Sustainability of the Soil and The
Environment. Communications in Soil Science and Plant Analysis.
Vol. 25 (1/2). Special issue with 29 articles.
Thus, it seems Wallace's observations jives with Joel Gruver's
findings that soil applied organic materials enhance soil aggregation
via polysaccarides. This is certainly true with the addition of
fresh green manures (or any other fresh organic matter), which
are rapidly attacked by soil microbes. The glues and slimes
released by the microbes during decomposition help to bind the
soil particles together. This is a desirable process, and one of the
reasons green manures are so widely used in organic crop production.
Joel suggests the addition of clays or soils to compost piles to
reduce Carbon loss. As an aside it is a common practice in
several of the European-derived compost systems to add clay loam at
10% by volume to enhance formation of the clay-humus crumb.
In thinking about this topic, it is probably helpful to look at
organic agriculture as a type of humus management system. It is the
integration of all the practices geared to enhancing soil quality and
building the humus bank in the soil -- crop rotations, crop residues,
mulch, cover crops, green manures, animal manures, composts,
microbial inoculants, grazing, urine, tillage implement etc -- that
make up the soil health picture.
Steve Diver
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