Organic Matter (OM)

      I just received a copy of the August/September edition of "Hay&Forage Grower" magazine.  An article  titled: Grazing boosts organic matter, written by Dennis Hanock of University of Georgia, had several things of interest to me.  The background for this article is, row crop land having been converted to pasture-based dairy farms.
       First interest, --is a short statement defining OM: --Scientifically speaking, soil OM is a collective term that refers to the amount of carbon-based material in the soil.  In a sense, soil OM quantifies the living component of the soil (such as roots, fungi, bacteria, and earthworms).  Too me, this is refreshing.  Mostly what I find as a definition for OM is a piece of the "collective term".
      Second, --is a short statement of why OM is important: --Soil organic matter acts as a sponge.  It holds water, improves the soil's cation exchange capacity, allowing it to hold more nutrients, and provides a host of other advantages.  This supports other source statements, but is a more compact statement.
      Third, --is a statement that a preliminary report from local research is showing the  primary source of OM buildup is from roots and root exudes, and not from litter left on the soil surface.  This research is supporting findings of a consortium of American and European scientists in a recent review published in the journal Nature.  I have been hearing and reading recently about the part litter plays in OM.  It's different than what I believed in the past; however, the above definition of OM plays to this.
      Fourth, --there is an indication that 3-4% OM in the top 4" is obtainable and gives dramatic results. Older pasture-based dairies indicate that OM stabilizes at the 3-4% level.  Newer studies are looking into this.
      These are the main points that I picked up on.  The context of these points can be put better into perspective by accessing and reading the article.   <hayandforage.com>