Humic Substances as Agronomic Inputs in Biological Agricultural Systems : a Review-Analysis of Humic Substances In Search of a Standard



It is important the Cation Exchange Capacity since these materials are rennowned for that characteristic , It should be in the range of 100 to 200as analyzed by the ammonium saturation method , Low pH is very important because the acidity initiates the dissolution of rock minerals , Low pH may be a broad indicator for open sites for chelating or complexing reactions to take place and an indicator of the relative concentration offunctional groups , A pH of about 3.8 is acceptable , An ash content over 10% is not unusual , indicating the degree of association with clay minerals or other contaminants , CEC , pH and ash analysis can be performed by many laboratories .

A large percentage of manufacturers are using the services of A&L Westem Agricultural Laboratories , Inc , to determine the quality of their humic substances , A&L offers two methodologies for humic substances analysis , the Califormia Department of Food and Agriculture method and the A&L Western Method , The CDFA Method is a quantitative analysis of humic acid , This method reports the acid insoluble fraction of humic material . The analysis is reported on an as received basis . The result can be mathematically converted to a dry matter basis report .

The CDFA method is based on the operational definition of humic acid , This technique , however , only uses a portion of the methodology described by the International Humic Substances Society method , which analyzes both humic acid and fulvic acid fractions . TheStandard Methods for Soil Analysis of the Soil Science Society of America , Madison , Wisconsin states that the IHSS method is broadly accepted and it can be performed in most laboratories . The CDFA method is a compromise because the fulvic fractions are completely ignored . The fulvic fraction is actually discarded during the process!

The A&L Western Method is a qualitative analysis , which may report all of the alkaline soluble humic materials in a sample , It consistently reports a higher percentage of humic acid than the CDFA method , It cannot be converted to a dry basis . The A&L Western Method may mimic some of the industrial process used to extract humic matter from oxidized lignite . However the base extraction method cannot discretely remove unwanted materials nor can it prevent the extracted materials from recombining with free radicals or contaminants , Therefor , the A&L Method more than likely includes non-humic materials as well as humic substances.

One person who has some experience analyzing oxidized lignites is Richard Lamar of EarthFax Engineering , Midvale , UT 84047 , a soil reclamation civil , geotechnical and environmental engineering firm , just to name a few , His lab is set up to analyze humic substances using techniques that are similar the IHSS protocola , Its a bit pricey , but Richard says he can get the pnce down in the future if there are sufficient requests for the service , He seems to understand the industry .

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