University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 54 1 2023 03 21 Comparison of structural diversity of humic acid types extracted from conventional organic sources in agriculture Comparison of structural diversity of humic acid types extracted from conventional organic sources in agriculture 123 134 92254 10.22059/ijswr.2023.347116.669340 FA Simin Khosravi Soil Science and Engineering department, College of Agriculture, Razi university, Kermanshah, Iran 0000-0002-9847-9472 Sareh Nezami Soil Science and Engineering department, College of Agriculture, Razi University, Kermanshah, Iran 0000-0002-8329-5849 Akram Fatemi Soil Science and Engineering Department, College of Agriculture, Razi University, Kemanshah, Iran 0000-0002-1675-8006 Journal Article 2022 08 13 Humic acid is an organic compound that can improve the physical, chemical and biological properties of soil. In addition, it plays an important role in increasing plant growth and yield. This composition can be extracted from various sources that are rich in organic materials such as composts, coal, humus materials and soil. In order to know the spectral and structural characteristics of this compound, humic acid was extracted from different organic sources in 2021. The amounts of carbon, oxygen, hydrogen and nitrogen elements in the extracted humic acids were determined by elemental analyzer, functional groups by FTIR and the spectrophotometric absorption ratios of E₃/E₅ and E₄/E₆ were determined by spectrophotometer in Department of Soil Science and Engineering laboratory, Razi University, Kermanshah. The lowest H/C ratio in the extracted humic acids was observed from municipal waste compost (1.05) and vermicompost (1.09), the highest O/C ratio was in humic acid extracted from municipal waste compost (0.70) and vermicompost (0.59), and the lowest C/N ratio was in humic acid of chicken manure (11.84). According to the results of FTIR analysis, the strongest absorption bands were observed at 3400 cm^-1, 2900-3000 cm^-1, 1600- 1700 cm^-1 and 1000-1100 cm^-1. The highest ratio of E₃/E₅ was found in humic acid extracted from chicken manure (12.81) and sheep manure (10.61) and the lowest amount was observed in municipal waste compost (2.00). The highest ratio of E₄/E₆ was obtained in humic acid extracted from chicken manure (7.31) and the lowest amount of E₄/E₆ was observed in humic acid obtained from municipal waste compost (4.70).  Humic acid is an organic compound that can improve the physical, chemical and biological properties of soil. In addition, it plays an important role in increasing plant growth and yield. This composition can be extracted from various sources that are rich in organic materials such as composts, coal, humus materials and soil. In order to know the spectral and structural characteristics of this compound, humic acid was extracted from different organic sources in 2021. The amounts of carbon, oxygen, hydrogen and nitrogen elements in the extracted humic acids were determined by elemental analyzer, functional groups by FTIR and the spectrophotometric absorption ratios of E₃/E₅ and E₄/E₆ were determined by spectrophotometer in Department of Soil Science and Engineering laboratory, Razi University, Kermanshah. The lowest H/C ratio in the extracted humic acids was observed from municipal waste compost (1.05) and vermicompost (1.09), the highest O/C ratio was in humic acid extracted from municipal waste compost (0.70) and vermicompost (0.59), and the lowest C/N ratio was in humic acid of chicken manure (11.84). According to the results of FTIR analysis, the strongest absorption bands were observed at 3400 cm^-1, 2900-3000 cm^-1, 1600- 1700 cm^-1 and 1000-1100 cm^-1. The highest ratio of E₃/E₅ was found in humic acid extracted from chicken manure (12.81) and sheep manure (10.61) and the lowest amount was observed in municipal waste compost (2.00). The highest ratio of E₄/E₆ was obtained in humic acid extracted from chicken manure (7.31) and the lowest amount of E₄/E₆ was observed in humic acid obtained from municipal waste compost (4.70).  https://ijswr.ut.ac.ir/article_92254_a0ac13299ac8105ebd968006a924c03a.pdf