Indicative extent of humic and fulvic acids in soils determined by electronic nose

Abstract

The principal humic substances present in soils like Humic Acid (HA) and Fulvic Acid (FA) are plant fertility components many of which basically are aromatic in nature. Assaying these components is a challenge. The present study aims at an enquiry to delineate aromaticity of soil extracted HA and extracted FA by capturing their odor. Since these soil components are bound to soil particles, an effort has been put to find out whether they are more released in dry or wet soil conditions. The aromaticity determination was explored by Electronic nose (E-nose) equipment that had specific array of metal oxide sensors. The other objective of the study was to profile the aromaticity of HA and FA by their extraction from garden soil and its subsequent amendment. The series of experiments comprised of extraction of HA and FA and profiling of Norm Aroma Index (NAI) by E-nose in both wet and dry conditions of soil. The findings were that the yield of HA was more compared to FA; the NAI noted was high in wet condition of the soil compared to dry soil; HA showed more aromaticity compared to FA; the amended soil showed more aromaticity compared to non-amended normal soils. Among the amendment exercises, HA amended soil showed maximum aromaticity. E-nose employment could indicate extent of HA and FA in soils.