1. IntroductionSoil constraints, such as sodicity, salinity, acidity, alkalinity and nutrient imbalances, are key factors limiting crop yields and affecting the sustainability of farming practices in Australia and globally (Dang et al., 2010a; Dang & Moody, 2016; Ulfa et al., 2022). Identifying and managing these constraints are crucial for optimizing agricultural productivity and ensuring food security. Soil chemical properties such as nitrate (NO3– ), electrical conductivity (ECe), pH, chloride (Cl), exchangeable sodium percentage (ESP), the concentrations of exchangeable Ca (ECa), K (EK), and Mg (EMg), have a significant impact on soil health and crop productivity (Alotaibi et al., 2023; Garello et al., 2023; González-Orozco et al., 2024; Meena et al., 2023; Rao et al., 2023). NO3– is essential for plant growth, providing readily available nitrogen (N) for uptake. However, imbalances in the N forms may affect the N cycle in ecosystems, leading to environmental issues such as leaching, acidification and volatilization, ultimately reducing N-use efficiency and causing nutrient losses (Tilman et al., 2002). ECe serves as a crucial indicator of soil health, reflecting the soil salinity levels and overall soil fertility. High ECe values typically indicate higher salinity, which could hinder plant growth, limiting water availability to plants and reducing crop yields (Rengasamy, 2006). Soil pH indicates soil acidity or alkalinity, with extreme pH levels potentially restricting the availability of essential nutrients like P, Ca, and Mg, while also causing toxicity of certain elements like Na, Al and Mn (Fageria & Baligar, 2008; Naorem et al., 2023; Orton et al., 2018; Ulfa et al., 2023). Chloride could impact plant health, particularly in sensitive crops, causing leaf burn and reduced photosynthesis (Bhoite et al., 2024; Munns & Tester, 2008). EK is vital indicators of soil health due to its role as a K reserve, whereas ECa and EMg are associated with poor soil health and an increased risk of dispersion. These exchangeable forms reflect the soil’s ability to retain essential nutrients necessary for plant growth and soil health. ECa is crucial for soil aggregation and root development, EK supports enzyme activity and stomatal water regulation, and appropriate EMg is important for crop quality, being a core component of chlorophyll and involved in enzyme activation (Naorem et al., 2023; Tiwari et al., 2020). Therefore, ECa, EK, and EMg are critical for both soil physical health and crop nutrition (Simoniello et al., 2022).Soil sampling and testing remain a critical step in assessing soil health and identifying constraints. Traditional methods involve collecting soil samples from various depths and analyzing them for key indicators such as available N (NO3– ), salinity (ECe), pH, Cl, and exchangeable cations. These indicators provide valuable insights into the soil’s fertility status and potential constraints. Studies have indicated that analyzing soil N parameters, such as NO3– , could help understand N cycle dynamics (Camargo & Alonso, 2006; Cookson et al., 2006; Das et al., 2024), while an ECe of 4 dS/m or higher in the soil saturation extract could indicate salinity, which could negatively impact crop production (Rengasamy, 2006). High Cl concentrations and sodicity in the subsoil have been identified as significant constraints that reduce water availability and crop yields in Australia’s northern grains region, with subsoil Cl proving to be a more reliable indicator of reduced water extraction and grain yields than salinity or ESP (Dang et al., 2011a; Dang et al., 2011b). Additionally, high ESP and EMg can cause soil dispersion, further compromising soil structure and crop productivity.Remote sensing technologies have revolutionized the identification of soil constraints. Tools like ConstraintID (https://constraintid.net.au/) utilizes satellite imagery to calculate enhanced vegetation indices (EVI), which reflect the peak greenness of fields (Ulfa et al., 2023). Higher EVI indicates more biomass, and consequently, likely higher yield (Orton et al., 2022; Ulfa et al., 2023). The EVI data, together with ground truthing, can be used to stratify agricultural land into consistently high (H), consistently low (L), and inconsistent (I) productivity zones. Such stratification supports targeted soil sampling and the identification of management zones to address specific soil constraints.We examine the differences in soil indicators across three productivity zones (H: consistently high yield, I: inconsistent yield, L: consistently low yield) and five soil depth layers (0-120 cm, D1-D5) at 21 sampling locations within Queensland, Australia. By analyzing these differences, we seek to identify the soil conditions that drive variations in EVI and impact crop yield. We hypothesize that significant differences in soil indicators (NO3– , ECe, pH, Cl, ESP, ENa, ECa, EK, EMg) exist between the three productivity zones within each soil layer (D1-D5) and that specific indicators are more strongly associated with observed differences in crop yield across these zones. To achieve this aim, the study addresses the following objectives: i) to assess the differences in soil indicators in various soil layers among the three productivity zones, ii) to associate particular soil constraints with the observed differences in crop yield among the three zones, and iii) to identify variations in soil constraints across different soil layers. This should help to clarify the implications of such variations in soil constraints have for soil management practices. Understanding the specific soil constraints that impact crop yield is essential for developing effective soil management strategies which will support optimal plant growth and maximize its yield potential.