A Critical Review for Real-Time Continuous Soil Monitoring: Advantages, Challenges, and Perspectives

Abstract

Most soil quality measurements have been limited to laboratory-based methods that suffer from time delay, high cost, intensive labor requirement, discrete data collection, and tedious sample pretreatment. Real-time continuous soil monitoring (RTCSM) possesses a great potential to revolutionize field measurements by providing first-hand information for continuously tracking variations of heterogeneous soil parameters and diverse pollutants in a timely manner and thus enable constant updates essential for system control and decision-making. Through a systematic literature search and comprehensive analysis of state-of-the-art RTCSM technologies, extensive discussion of their vital hurdles, and sharing of our future perspectives, this critical review bridges the knowledge gap of spatiotemporal uninterrupted soil monitoring and soil management execution. First, the barriers for reliable RTCSM data acquisition are elucidated by examining typical soil monitoring techniques (e.g., electrochemical and spectroscopic sensors). Next, the prevailing challenges of the RTCSM sensor network, data transmission, data processing, and personalized data management are comprehensively discussed. Furthermore, this review explores RTCSM data application for updating diverse strategies including high-fidelity soil process models, control methodologies, digital soil mapping, soil degradation, food security, and climate change mitigation. Finally, the significance of RTCSM implementation in agricultural and environmental fields is underscored through illuminating future directions and perspectives in this systematic review.

A new paradigm of reliable sensing with field-deployed electrochemical sensors integrating data redundancy and source credibility

“…Pseudocode of the true signal and credibility estimation is provided in supplementary information section S2 and window size, overlap size, and quantization levels used in the analysis of synthetic and real sensor datasets (in Figs. 2,3,4,5) are reported in the supplementary information Table S2. We also show the impact of varying window size, N and quantization levels, K on the quality of estimated signal from MLE in the supplementary information Fig.…”

“…Reliable sensing with integrated sensors is a prerequisite for continuous monitoring and automatic control systems. Wearable and implantable electrochemical sensors that measure analyte concentrations onsite have potential applications in a variety of systems, e.g., personalized healthcare 1 , 2 , smart agriculture 3 , wastewater management 4 , chemical, and biological process monitoring 5 , etc. Despite vast opportunities, wearable and implantable electrochemical sensors have not yet attained accuracy levels comparable to those used in the laboratory setting 6 , 7 .…”

At-Field and On-Demand Nitrogenous Fertilizer Synthesis

“…Electrochemical sensors are mainly classified into three types including potentiometric, voltammetric, and conductometric methods (Figure ). These sensor types have been widely used for nitrogen monitoring in water including natural resource water, drinking water, and wastewater, but few studies have focused on electrochemical sensors for soil nitrogen measurement devices . The barriers to implementing electrochemical sensors in soil are mainly attributed to interferences from soil chemical and biological components and variations in soil environment, which severely restrict the at-field application of electrochemical nitrogen sensors in soil.…”

“…In a soil sensing application, an irrigation controller was used to normalize the desired moisture level in agricultural soil by controlling the water flow of irrigation pumps according to soil moisture data . However, these control strategies are always constrained by historical and discrete monitoring data due to the lack of advanced sensing techniques with high temporal resolution . In contrast, real-time electrochemical soil nitrogen sensors can provide an opportunity to revolutionize at-field nitrogen fertilizer control by providing continuous and high-temporal-resolution soil nitrogen data sets.…”

“…75 However, these control strategies are always constrained by historical and discrete monitoring data due to the lack of advanced sensing techniques with high temporal resolution. 61 In contrast, real-time electrochemical soil nitrogen sensors can provide an opportunity to revolutionize at-field nitrogen fertilizer control by providing continuous and hightemporal-resolution soil nitrogen data sets. These highresolution data could enable real-time self-parameter tuning for rN production, and thus assist operational adjustments under different conditions such as transient nitrogen waste shocks.…”