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  • From: "Tradingpost" <tradingpost@lobo.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] soil organic matter from Albrecht
  • Date: Mon, 07 Jul 2008 22:49:29 -0600


This is a post of mine to Soilmakers from Dec 2005 - followup to Mark's
article

paul tradingpost@lobo.net
------------------------------------------

So let me recommend this classic to everyone:
http://www.soilandhealth.org/01aglibrary/010120albrecht.usdayrbk/lsom.html
Loss of Soil Organic Matter and Its Restoration, By William A. Albrecht,
Professor of Soils University of Missouri.

"In addition to carrying nitrogen, the nutrient demanded in largest amount
by plants, soil organic matter either supplies a major portion of the mineral
elements from its own composition, or it functions to move them out of their
insoluble, useless forms in the rock minerals into active forms within the
colloidal clay. Organic matter itself is predominantly of a colloidal form
resembling that of clay, which is the main chemically active fraction of the
soil. But it is about five times as effective as the clay in nutrient
exchanges. Nitrogen, as the largest single item in plant growth, has been
found to control crop-production levels, so that in the Corn Belt crop yields
roughly parallel the content of organic matter in the soil (184). On a
Missouri soil with less nitrogen than that corresponding to 2 percent of
organic matter (40,000 pounds of organic matter per acre of plowed surface
soil) an average yield of 20 bushels of corn per acre can hardly be expected.
For yields approaching 40 bushels, roughly double the amount of organic
matter is required. With declining organic matter go declining corn yields
and therefore lower earnings on the farmers investment. Thus the stock of
organic matter in the soil, particularly as measured by nitrogen, is a rough
index of land value when applied to soils under comparable conditions.
According to studies in Missouri, for example, the lower the content of
organic matter of upland soil, the lower the average market value of the
land."

Demonstrations he cited showed that heavy cropping demands much more organic
matter added annually than most growers realize, to maintain soil structure
and the heaviest production. Cover cropping, rotations, and green manuring of
course reduce demands somewhat. He goes into the need for minerals in the
process of decomposition, the need for nitrogen in the process, and
differences due to climate. A classic. One of the reasons why I believe the
cost of replacing huge amounts of organic matter is paid back many times
over, and why I believe great gains in yield and nutritive value can be made
by using far more organic matter (including minerals).





  • [Livingontheland] soil organic matter from Albrecht, Tradingpost, 07/08/2008

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