Advancing Soil Security with Soil Spectroscopy: The efficient estimation of indicators

Soil security is fundamental to addressing global existential challenges, as it encompasses the sustainable management of soils for future generations. The soil security assessment framework consists of five dimensions, which reflect the roles of soil in supporting ecosystems and human livelihoods: soil functions, soil services, and resilience to environmental threats. Of these, two biophysical dimensions, Capacity and Condition, are central. Capacity refers to the inherent ability of soil to perform its functions, while Condition represents the current state of the soil, often associated with soil health. However, assessing these dimensions can be challenging, as many of the key soil properties that indicate soil capacity and condition are costly and labour-intensive to measure. Recent advancements in soil sensing technologies, particularly spectroscopy, offer a promising solution. Spectroscopy enables rapid, non-destructive, and cost-effective estimation of a wide range of soil properties, providing an efficient alternative to traditional laboratory analysis. This technology facilitates both temporal and spatial monitoring of soil health, offering significant advantages in large-scale soil assessments. This study identifies key soil roles that can be measured using spectroscopy, often in combination with pedotransfer functions (PTFs). Through an extensive literature review, we compared the performance of four analytical techniques: visible-near infrared (Vis-NIR), mid-infrared (MIR), X-ray fluorescence (XRF), and laser-induced breakdown spectroscopy (LIBS). Our findings indicate that MIR offers the broadest range of soil properties that can be accurately predicted. Moreover, several soil indicators remain under investigation across different spectroscopic methods, highlighting the potential for further refinement and application of these technologies in soil monitoring.