EVALUATION THE EXTRACTION METHODS OF HUMUS ACIDS FROM VARIOUS ORGANIC SOURCES AND THEIR EFFECT ON THE CHEMICAL BEHAVIOR OF PHOSPHOROUS IN THE SOIL

Abstract

This study was carried out in order to evaluate the efficiency of some compounds in extracting humus acids (humic and fulvic) from various organic sources and to evaluate the efficiency of the extracted acids in phosphorous availability in the soil. Three chemical compounds were selected for the extraction, which were 0.1 standard of sodium pyrophosphate Na4P2O7, 0.5 standard of sodium hydroxide NaOH, and a 0.1 standard mixture solution of Na4P2O7 and 0.5 standard of NaOH and symbolized as M1, M2, M3 and four organic residues (corn molasses O1, licorice O2, O3 poultry, and O4 sheep Residues). The humus acids were extracted by adding extraction solutions to the organic residues in a ratio of 1:10 solution: organic matter and the purification and separation process was carried out using a centrifuge. The chemical composition of the extracts was analyzed and the organic acids concentrations were determined. The efficiency of these extracts was tested in the laboratory in terms of phosphorus adsorption and release by conducting an adsorption and release experiment. The results revealed that the effect of the extraction method and the type of organic residue on the concentrations of the extracted humic and fulvic acids, as the concentration of humic acid was significantly higher than the fulvic acid in all treatments by 80%. The concentration of humic acid extracted from animal Residues increased by 283% compared to plant Residues. While for the fulvic acid, the increment was by 539%. As for the extraction method, the M3 treatment was significantly higher than the treatments M1 and M2 by 87% and 33% for humic acid, 324% and 11% for fulvic acid, respectively. The adsorption and release experiment also showed a high efficiency of extracted acids in reducing the values of binding energy and maximum adsorption, and the humic acid was significantly higher than fulvic acid in reducing the values of binding energy and maximum adsorption by 81% and 17% respectively. The results also revealed the significant increment of humic acids extracted from animal residues compared to plant residues in a ratio of 43% and 7% for each of the binding energy and the maximum adsorption. Humic acid was significantly higher in reducing binding energy and the maximum adsorption by 57% and 10% compared to fulvic acid. As for the extraction methods, the treatment of M3 was significantly higher than the treatments M1 and M2. Moreover, in the effect of organic residue, the treatment of O3 was significantly higher than O1, O2 and O4.