Genesis and Classification of A-Type Humic Acids in Ando Soils

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a. Two methods of extracting humic acids were tested an compared for efficiency. One method, which is commonly practiced, made use of soil pre-treated with 0.5% NaOH and then soaked in boiling water bath at 100ﾟC. The other method made use of the same pre-treatment and shaken for one hour at room temperature. It was found out that the latter method was more effective because of the simplicity of the method and clear trend of results produced.b. Properties of humic acids were determined using the following indices : DELTA log K, color density, melanic index and Pg index to identify 5 types of humic acids, four of which are A-type humic acids.C. IR and NMR methods were used to determine the aliphatic and aromatic compounds of the A-type humic acids at varying color densities. Aliphatic peaks were strongest at low color densities and aromatic peaks were strongest at higher color densities.d. It can be said that color density is a good optical index of determining the properties of humic acids.e. Thin section microscopy method has been used to determine the properties of soil. Present study or investigation to determine the structure of humus using the said method is being conducted by the researcher.Effective size of soil thin section is still being determined through trial and error method. Sizes of 25 x 40 mm, 50 x 70 mm and 80 x 100 mm are being tested. Correlation of soil micromorphology with A-type humic acid properties are being considered to be taken in future studies.