Spatial and temporal variability of soil health scores and their relationship to crop yield

Soil health is the continued capacity of the soil to function as a vital living ecosystem that sustains plants, animals, and humans. To assess and evaluate soil health, the Comprehensive Assessment of Soil Health (CASH) was established. In CASH, different soil health indicators are used to assign a score. These indicators are soil properties that can vary spatially and temporally. In this study, soil health scores were determined across a landscape to evaluate their spatial and temporal variability and then used to evaluate the relationship between the scores and crop yield. The study evaluated physical, chemical, and biological soil properties, which were scored based on the CASH scoring system. Soil samples were collected throughout five seasons from twenty-four different blocks for various indicators. Based on the results it showed that soil health score varied through space and time. The effect of block was significant on soil health score (p = 0.001). This significant effect of space can be due to varying soil properties in the field such as soil texture. Throughout the seasons, the scores were relatively different within blocks. The analysis also showed that block and season interactions were significant (p < .001) suggesting that differences among blocks were not consistent across all sampling seasons but instead emerged under specific seasonal conditions. Linear regression models were used to examine the relationship between soil health score and yield. Although the relationship between soil health score and wheat yield during the summer season was statistically significant (p = 0.05), the model explained only a small portion of the yield variability (R² = 0.16), indicating that factors other than soil health influenced yield outcomes. Multiple linear regression analysis revealed that extractable potassium and organic matter had the strongest positive standardized effect on yield, whereas soil respiration and extractable phosphorus were negatively associated with yield. This result indicates that nutrient availability and carbon content are critical contributors to crop productivity.