Exploring soil property spatial patterns in a small grazed catchment using machine learning

Abstract

Acquiring comprehensive insights into soil properties at various spatial scales is paramount for effective land management, especially within small catchment areas that often serve as vital pastured landscapes. These regions, characterized by the intricate interplay of agroforestry systems and livestock grazing, face a pressing challenge: mitigating soil degradation while optimizing land productivity. This study aimed to analyze the spatial distribution of eight topsoil (0–5 cm) properties (clay, silt, sand, pH, cation exchange capacity, available potassium, total nitrogen, and soil organic matter) in a small grazed catchment. Four machine learning algorithms—Random Forest (RF), Support Vector Machines (SVM), Cubist, and K-Nearest Neighbors (kNN)—were used. The Boruta algorithm was employed to reduce the dimensionality of environmental covariates. The model’s accuracy was assessed using the Concordance Correlation Coefficient (CCC) and Root Mean Square Error (RMSE). Additionally, uncertainty in predicted maps was quantified and assessed. The results revealed variations in predictive model performance for soil properties. Specifically, kNN excelled for clay, silt, and sand content, while RF performed well for soil pH, CEC, and TN. Cubist and SVM achieved accuracy in predicting AK and SOM, respectively. Clay, silt, CEC, and TN yielded favourable predictions, closely aligning with observations. Conversely, sand content, soil pH, AK, and SOM predictions were slightly less accurate, highlighting areas for improvement. Boruta algorithm streamlined covariate selection, reducing 23 covariates to 10 for clay and 4 for soil pH and AK prediction, enhancing model efficiency. Our study revealed spatial uncertainty patterns mirroring property distributions, with higher uncertainty in areas with elevated content. Model accuracy varied by confidence levels, performing best at intermediate levels and showing increased uncertainty at extremes. These findings offer insights into model capabilities and guide future research in soil property prediction. In conclusion, these results urge more research in small watersheds for soil and territorial management.

Application of the improved Probabilistic Fuzzy Logic Inference Engine Model to evaluate Mineralization Prospectivity - Taking the Gejiu region of Yunnan, China as an example

“…Nowadays, uncertainty analysis in various studies in the field of earth science has made progresses, such as in hydrology, three-dimensional geological structure model, meteorological problem, climate change problem, soil research, hydrology and structural analysis, mineral deposit grade prediction and seismology. (Yifru et al 2023;Liang et al 2021;Boller et al 2010;Anderson et al 2011;Barrena-González et al 2023;Abbaszadeh et al 2021;Afsari et al 2022. ) At present, most mineralization prospectivity work is based on providing the location, abundance and reserves of predicted minerals.…”