alkaline soil conditions. Table One indicates that there are 40 
elements which should be retained with the soil profile. 
Mobilization of elements is strongly influenced by Eh 
(ionization potential), pH and the stability of minerals within 
the soil. 
Brooks (1972) described four main factors responsible for 
mobilization and distribution of the elements. 
1) Mobilization due to breakdown of soil by weathering and leaching. 
2) Adsorption of ions on clay minerals and humus. Clay has an ion 
exchange capacity of up to 100 meq/100g; humus has a 500 
meq/ 100g capacity. 
3) Surface enrichment of elements by plant material. Here plants 
cycle particular elements by absorping from the soil, incorporating 
into their tissue, and enriching the surface by littering. The humus 
layers will be enriched relative to the stability of metal complexes 
with organic matter. 
4) Mobilization or fixation by soil micro-organisms, particularly 
bacteria. Although insignificant in weight, their metabolic 
processes effectively handle large quantities of material. 
Given these four factors, we may immediately realize that there 
will be chemical partitioning between the mobile and immobile 
elements and the efficiency of chemical traps. 
Notwithstanding the problems of mobility, there are 40 
elements which may be useful in interpreting plant residue. 
2) WHAT IS THE SIGNIFICANCE OF ELEMENTAL CONCENTRATIONS? 
As a plant seeks to establish itself, it employs the following 
methods with respect to the elemental composition of the soil. 
—First, it demonstrates an exclusion mechanism through which 
qualitative and quantitative regulation of absorbed elements is 
accomplished. This mechanism occurs primarily at the roots, 
although it may occur somewhat in the canopy. 
—Secondly, this action of elemental uptake is related to function, 
and that function is the production of compounds. These 
compounds range from metabolic intermediates, various 
vitamins and catalysts through pigments such as chlorophyll to 
particular enzymes such as those associated with respiration and 
membrane repair. 
Some additional compounds produced demonstrated a “social” 
function, like those that promote mutualism, such as insect 
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