Healthy soil and sustainable growing

[Steve Diver <steved@ipa.net>]

The Organic Matter expressed on a typical soil test
is percent OM on a dry weight basis.  So if you are living
in the South it might say 1-2% OM, while if you live
in a more northernly location such as Pennsylvania it
might say 3-5%.

The Humus Value test is a relative value between 0 to
100.   There is no percent.  It is a number that is
equated with degree of colored solution resulting from
a sodium hydroxide extraction, which further correlates
to degree of organic matter humification.  The LaMotte
STH Soil Test Kit includes the colorimetric humus
screening test.

My paper on Luebke compost explains it in greater detail.

Controlled Microbial Composting and Humus Management:  Luebke Compost
by Steve Diver, Fayetteville, Arkansas
http://www.ibiblio.org/steved/Luebke/Luebke-compost2.html

When you use all of the tests together, the humus value indicator
is very useful and insightful.  

Hope this helps make it clearer,

Steve Diver



Catherine Fenner wrote:

> Thank you so much for posting this. Now I feel like I'm cooking with gas.
>
> Please correct me if I'm misunderstanding what you're saying. What I think
> you're saying in the quote below is that there are two tests; one for what
> percentage of organic matter is in the soil and the second is the percentage
> of humus?
>
> Somehow I think I'm not quite getting this.
>
> Catherine
>
> -----Original Message-----
> Soil testing methods can ascertain the percent organic matter on a dry
> weight basis using acid digestion of soil
> samples.   This is the percent OM that is displayed on a 
> soil test.
>
> But there is a second test known as the Humus Value test which is available
> thru several labs or by using your own test kit.  It is a sodium hydroxide
> extraction, then determined by colorimetry.  It is expressed as a relative
> value from 0 to 100.  The higher the number the *darker* the color, and the
> higher degree that organic matter has undergone
> humification.