Steve Diver and Jim McNelly,

	Although the issue of amounts and quality of humus is in my 
opinion very important, it is the broader concept of soil organic matter 
(in all its complexity) that is really the key to sustainable 
agriculture. The approach I took when writing my book (Building Soils for 
Better Crops: organic matter management - Univ. Nebraska Press) is that 
by managing soils to build up and maintain high levels of soil organic 
matter most of the problems farmers run into when growing plants will 
either be lessened or eliminated. Issues of biodiversity of soil 
organisms, non-humic materials helping stabilize soil aggregates,  etc. 
indicates that one must do more than just consider the humus portion of 
soil organic matter.

Fred Magdoff