Phenolic Acids in Soils Soil Extractions and Dose Response

1 Phenolic Acids in Soils Soil Extractions and Dose Response 

The two methods most Irequently used to establish that inhibited plants are in contact with and interact with organic inhibitors produced by putative allelopathic plants or plant residues and to establish that these inhibitors are present at sufficient concentrations and for sufficient lengths of time are soil extractions and dose response studies. You may have noticed that this was the approach taken for the research presented in this book. There are, however, now several aspects of this approach that are troubling. 

Phenolic acids in soil solutions, reversibly sorbed on soil particles, and on and in plant residues range from simple phenolic acids (e.g., ferulic acid) to complex polymers, such as tannins. Soils and residues also contain a variety of polymers that contain phenolic acid moieties, e.g., humic acid, fulvic 

Even if we could extract all of the available/active phenolic acids with a single extraction procedure their different physical and chemical properties and then-large number would make it essentially impossible to identify and quantify them all. 

Soil extractions cannot differentiate between sources of phenolic acids, e.g., are they from shoots or roots of the putative allelopathic plant or the receiving plant, are they from plant residues on or in the soil, are they from faunal and microbial activity on new or old organic residues in the soil, etc. 

---