## 4 Discussion
### Further Research Directions and Applications  
In this study, we employed a transect approach across adjacent land use types within a geographically and ecologically uniform region. This controlled design was specifically implemented to rigorously evaluate the performance of our multivariate statistical framework under conditions where similar volatile organic compounds are present across sites, but their intensities differ. Our method was primarily assessed for its capacity to delineate land use types even when common volatile organic compounds vary quantitatively. However, we acknowledge that variations in geographical locations, broader ecological environments, and soil types may affect both the composition and intensity of the soil volatilome profile in other regions. Therefore, while our land use transect sampling design was appropriate for testing the method's efficiency under controlled variability, the generalizability of our findings to more heterogenous regions may be limited. Future research shouldextend this methodological framework to diverse settings to further elucidate the impact of regional and environmental variability on soil volatilome profiles. Further, the designation of specific volatile markers as universal indicators of soil quality extends beyond our current methodological scope due to several inherent limitations. Our transect-based study, while optimized for validating a robust statistical framework across adjacent land use types, captures only a spatiotemporal snapshot of the soil volatilome profile. The compex, dynamic nature of the soil volatilome, where compounds serve multiple ecological functions and exhibit quantitative rather than qualitative variations, necessitates longitudinal studies across diverse ecosystems to establish reliable quality indicators. Furthermore, the potential influence of geographical, ecological, and pedological variations on the volatilome's composition and intensity suggests that marker compound identification requires broader spatial replication. These limitations present opportunities for further research to employ our validated statistical framework in comprehensive temporal and spatial studies aimed at identifying and validating universal volatile markers of soil quality across heterogenous environments. Future research should aim to integrate soil volatilomics using metagenomics, transcriptomics, and metabolomics to establish a comprehensive system-level understanding of soil biochemical networks. This integration would allow researchers to correlate specific volatile organic compounds with microbial gene expression profiles and metabolic pathways, thereby elucidating the mechanistic relationships between soil chemistry and microbial function. Combining these approaches makes it possible to develop predictive models that link soil management practices with alterations in ecosystem functionality, offering a more robust framework for tracking biogeochemical cycles and diagnosing ecological stress. Moreover, advancing soil volatilomics necessitates the development of high-resolution, time series, and spatial sampling methodologies. Such studies should focus on capturing dynamic changes in volatilome profile patterns across different soil depths and seasonal cycles. These investigations enhance our understanding of fluctuations in soil ecosystem processes under varying environmental conditions and management practices. This refined monitoring can facilitate the early detection of ecosystem disturbances and help delineate the spatial gradients of soil health, thereby supporting more precise land management and restoration strategies. Expanding the application of soil volatilomics to environmental impact assessments could significantly increase the detection and quantification of anthropogenic influences on soil systems. Investigations should explore how shifts in volatilome profiles correlate with broader ecological indices, such as nutrient cycling efficiency and carbon sequestration potential.