Soil Organic Matter (SOM) is an important component in the global carbon cycle, including
more than three times as much carbon as both the atmosphere and the terrestrial vegetation. However, it
is difficult to analyze soil organic matter chemistry due to its complexity and diversity resulting from
microbial and physicochemical transformations of organic remains of vegetal, microbial and animal origins.
Pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS) is a quick analytical technique to
obtain clarity in molecular components in which the sample is heated to decomposition to produce
smaller molecules that are separated by gas chromatography and detected using mass spectrometry. In
the recent years, SOM chemical characteristic of different ecosystems has been studied with its responses
to climate change and human activity. The goal of this review is to highlight chemical characteristic
of SOM at the molecular level, and to compare soils under different ecosystems, further to illuminate a
given soil under various impacts, such as climate conditions, land use change, cultivation pattern and
fire disturbance, based on Py-GC/MS analytical technique.