Farming shallow soils: Impacts of soil depth on crop growth in the Everglades Agricultural Area of Florida, USA

Context: Over half of the US's sugarcane production comes from the Everglades Agricultural Area (EAA) in Florida (USA). However, the loss of organic soils due to oxidation, which results in the gradual reduction of soil depth, poses a significant concern for the future of agriculture throughout the EAA. Understanding the relationship between soil depth and crop production in the EAA is critical to developing sustainable and profitable farming practices in the region. Objective: This study aimed to assess the depths of organic soils in the EAA and monitor the growth of sugarcane to elucidate the relationship between crop growth and soil depths. Methods: The soil depth of five locations spanning a total area of 90 ha were surveyed. The sugarcane yield was estimated using the Normalized Difference Vegetation Index (NDVI) derived from publicly available Landsat 8 satellite images. Results: The soil survey revealed considerable spatial variation in soil depths, ranging from 10 to 105 cm with an average of 51 cm. Over half of the study area had soil depths below 50 cm, while only 11.9 % of the area had soil depths exceeding 80 cm. Multiple linear regression analysis indicated sugarcane variety and age significantly impacts the yield. However, no significant relationship was found between soil depth and sugarcane yields, which can be attributed to the ample availability of nutrients and water in the region, coupled with advancements in agricultural technologies such as stringent soil testing for nutrient recommendations and effective plant breeding that address the constraints posed by shallow soils. Conclusions: The undetectable threshold for soil depth where crop yields decline may be due to numerous reasons including dataset constraints, and modelling limitations. For sugarcane production to be sustainable and profitable in the region soil loss of Histosols in the region warrants further research. Proactive interventions and conservation farming practices are imperative to mitigate soil loss within the region. Implications: The outcomes of this study furnish valuable data to support decision-makers in policy formulation, with significant implications for food security and environmental sustainability.