What are the relationships (synergistic or antagonistic) between organics input in soil and Cu content in soil and plant, without adding any external source of Cu in soil?
The relationship in soil is synergistic. With increase in organic matter content Cu retention has increased with a small percentage retained in the exchangeable Cu fraction. In general, organic matter fraction contributed highest to Cu content found in the soil extract.
Most of the function of Cu as plant nutrient are based on participation of enzymatically bound Cu in redox reactions. In the redox reactions of the terminal oxidases Cu enzymes react directly with molecular oxygen. Terminal oxidation in the living cells catalysed by Cu and not by Fe. Cu can form highly stable complexes and easy electron transfer.
Cu has a high affinity for peptide and sulfhydral groups as well as for carboxylic and phenolic groups. Therefore in the soil solution as well as in the roots and in the xylem sap more than 98-99% of the Cu is present in complexed form.
Very good and question of practical nature has been placed by Dr Meena. There is mostly positive relationship between organic matter and micro nutrient including Cu.
In a previous work (1995), using a step-wise variable selection technique, it was found that the variation of Fe extracted by EDTA was mostly explained by pH, organic matter content, active calcium carbonate and clay content, while a significant proportion of the variation of Zn and Mn extracted by DTPA was interpreted by pH and
organic matter content. Copper as CuEDTA and CuDTPA were weakly influenced only by pH.
Yes, I agree to Nikolaos that pH is another determinant of Fe, Zn and Cu in addition to organic matter content.and soil texture.
Interesting discussion friends. The suggested relationship would be surely synergistic , while considering the Cu-availability and organic matter additions in the soil , unless the soil is calcareous or salt affected. It has long been observed that the number of rings within a particular chelate structure results in the greater stability of the Cu- chelate. T he chelate effect is the enhanced affinity of chelating ligands for a metal ion compared to the affinity of a collection of similar nonchelating (monodentate) ligands for the same metal.Many microbial species produce water-soluble pigments that serve as chelating agents, termed siderophores. For example, species of Pseudomonas are known to secrete pyochelin and pyoverdine that bind iron. Enterobactin, produced by E. coli, is the strongest chelating agent known.
Any stress on any individual ring in metal polydentate chelates does not generally tend to be deposited in the same ring, but rather spreads to some extent over the whole fused-ring system, sometimes strengthened and at other times weakened or even completely cancelled by another stress on another ring in the system. Therefore, the stability of fused rings should not be discussed on the basis of a simple summation of the stability of individual rings contained in the fused-ring system. It has been concluded that the stability of metal polydentate chelates increases with a decrease in stress over the whole fused-ring system. On the other hand , i do agree copper chelates are more stable than iron, manganese or zinc chelates...
Very good explanation of the relationship between soil O.M. and micro nutrients by Dr. Kumar.
Yes, addition of organic manures add to the availability of all the nutrients including Cu, though the rate may vary with the time and edaphic conditions. Thanks for adding to our knowledge.
In general, there is no doubt that the relationship between Cu-availability and organic matter would be surely synergistic, but the rate of Cu-availability under organic matter varies with edaphic condtions.
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