Plant & Soil Sciences eLibraryPRO
Loading
control panel control panel
 

Soils - Part 3: Soil Organic Matter

Rate Me

Secondary Effects of Soil Organic Matter

The previous discussion covered some of the direct effects of soil organic matter, mainly on soil structure. There are other effects of soil organic matter which are not so visible, but which may be just as important as improved structure.

Organic matter is a reservoir of certain plant nutrients, especially nitrogen, phosphorus, and sulfur. Many soils have 90 percent or more of their total nitrogen present in organic materials. The figures are smaller for phosphorus and sulfur, but are still significant. These organic reserves act as a bank account of nitrogen, phosphorus, and sulfur for plants. Actually, a better analogy might be that organic materials are a nutrient variable rate annuity. The plant can’t use organic nitrogen any time it wants, just like you can’t access a variable rate annuity until it comes to term. Organic forms of nutrients must be mineralized, or converted to inorganic forms, to be useful to plants. This is largely carried out by microorganisms as a byproduct of their use of organic matter for themselves.

A second indirect benefit of organic matter in soils is in increasing a quantity called cation exchange capacity (CEC). Cation exchange capacity is the ability of a soil to hold certain elements which have a positive charge, called cations. Some plant nutrients, such as potassium and calcium are cations, so a soil with a higher CEC will generally be more fertile because of its higher content of these nutrients. While there are exceptions to this generalization, it provides one more reason to see higher organic matter content as a benefit to the soil and to the crop being grown on the soil.

Comments

Be the first to write a comment...

Control Panel cancel

Create activities for your moodle courses. Moodle Go to moodle
Select and group e-Library Lessons to create your own package... My Communities
Community Blogs Community Media

My Joined Communities

 
My Blogs - a journal of my thoughts... My Blogs
 
My Comments - my thoughts expressed as a feedback... My Comments
 
Classes that I am taking Registered Classes
Class Blogs Class Media
 
Check the scores of assesments that you have taken Taken Assessments
 
clear
Please confirm your selection.