Healthy soil and sustainable growing

["Tradingpost" <tradingpost@lobo.net>]

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).