Assessing the Role of Environmental Covariates and Pixel Size in Soil Property Prediction: A Comparative Study of Various Areas in Southwest Iran
Abstract
:1. Introduction
2. Materials and Methods
2.1. Description of Study Sites
2.1.1. Reference Area
2.1.2. First Receptor Area
2.1.3. Second Receptor Area
2.2. Soil Sampling and Laboratory Analysis
2.3. Auxiliary Variables and Scales Scenarios
2.3.1. Auxiliary Variables
2.3.2. Scales Scenarios
2.4. Similarity among Sites
2.5. Spatial Modeling
Extreme Gradient Boosting Trees
2.6. Model Validation
3. Results
3.1. Summary Statistical of Soil Properties
3.2. Selected Environmental Covariates
3.3. Similarity Index
3.4. Model Validation
3.4.1. Model Validation at Different Scales Scenarios in the Reference Area
3.4.2. Model Validation in the Receptor Area (First and Second Receptor Areas)
3.5. Covariate Importance
3.5.1. Covariate Importance in the Reference Area
3.5.2. Covariate Importance in Receptor Areas (First and Second Receptor Areas)
3.6. Spatial Prediction
3.6.1. Spatial Prediction Maps in the Reference Area
3.6.2. Spatial Prediction Maps in the Receptor Areas
First Receptor Area
Second Receptor Area
4. Discussion
5. Research Strengths and Weakness/Limitations
5.1. Strengths
5.2. Weakness/Limitations
6. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Category | Covariates | Sources | Description | Basic Resolution |
---|---|---|---|---|
Optical images | Surface reflectance of vegetation cover | GEE platform (https://earthengine.google.com/—May to August 2021) | Sentinel-2 Level 2A surface reflectance | B2, B3, B4, B8: 10 m B11, B12: 20 m |
Landsat 8 (OLI) images | B2, B3, B4, B5, B6, B7: 30 m | |||
Terrain attributes | Topographic condition of landscape | ASTER Global Digital Elevation Model (GDEM) from GEE platform | DEM derivation from SAGA GIS software (4.7) | 30 m |
Soil Fertility Attributes | Area | Minimum | Maximum | Mean | SD | CV (%) |
---|---|---|---|---|---|---|
SOM (%) | Reference | 0.22 | 3.22 | 1.66 | 0.32 | 19.2 |
First receptor | 0.62 | 3.79 | 1.71 | 0.42 | 24.5 | |
Second receptor | 0.46 | 2.10 | 1.14 | 0.36 | 31.5 | |
MWD (mm) | Reference | 0.32 | 2.43 | 2.06 | 2.09 | 38.8 |
First receptor | 0.93 | 5.50 | 2.48 | 1.05 | 42.3 | |
Second receptor | 0.24 | 1.64 | 2.25 | 1.01 | 44.8 | |
BD (gr·cm−3) | Reference | 0.45 | 1.79 | 1.28 | 0.28 | 21.8 |
First receptor | 0.56 | 1.87 | 1.29 | 0.35 | 27.1 | |
Second receptor | 0.36 | 1.95 | 1.14 | 0.46 | 21.9 | |
SS (kPa) | Reference | 0.14 | 2.63 | 2.43 | 2.60 | 49.7 |
First receptor | 0.50 | 4.10 | 2.10 | 1.14 | 54.28 | |
Second receptor | 0.10 | 4.00 | 1.04 | 0.56 | 53.8 |
SCORPAN Factors | Parameter | Abbreviation | Source |
---|---|---|---|
o | Brightness | Brightness | RS |
o | Perpendicular Vegetation Index | PVI | RS |
o | Wetness | Wetness | RS |
o | Normalized different vegetation index | NDVI | RS |
o | Greenness | Greenness | RS |
r, c | Diffuse Insolation (kWh/m2) | DI | DEM |
r, c | Wind Effect | WE | DEM |
r | Valley depth (m) | VD | DEM |
r | LS Factor | LS | DEM |
r | Channel Network Base Level (m) | CNBL | DEM |
r | Channel Network Distance (m) | CND | DEM |
Soil Properties | Scales (m) | R2 | CCC | RMSE | nRMSE | MAE |
---|---|---|---|---|---|---|
SOM (%) | 1200 × 1200 | 0.46 | 0.51 | 0.30 | 0.17 | 0.28 |
MWD (mm) | 2100 × 2100 | 0.65 | 0.70 | 0.29 | 0.11 | 0.25 |
BD (gr/cm3) | 180 × 180 | 0.25 | 0.30 | 0.24 | 0.18 | 0.22 |
SS (kPa) | 1200 × 1200 | 0.50 | 0.55 | 0.30 | 0.14 | 0.28 |
Soil Properties | Scales (m) | R2 | CCC | RMSE | nRMSE | MAE |
---|---|---|---|---|---|---|
SOM (%) | 1200 × 1200 | 0.64 | 0.68 | 0.37 | 0.32 | 0.29 |
MWD (mm) | 2100 × 2100 | 0.60 | 0.65 | 0.20 | 0.08 | 0.15 |
BD (gr/cm3) | 180 × 180 | 0.52 | 0.54 | 0.31 | 0.27 | 0.27 |
SS (kPa) | 1200 × 1200 | 0.58 | 0.62 | 0.85 | 0.81 | 0.77 |
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Khosravani, P.; Baghernejad, M.; Taghizadeh-Mehrjardi, R.; Mousavi, S.R.; Moosavi, A.A.; Fallah Shamsi, S.R.; Shokati, H.; Kebonye, N.M.; Scholten, T. Assessing the Role of Environmental Covariates and Pixel Size in Soil Property Prediction: A Comparative Study of Various Areas in Southwest Iran. Land 2024, 13, 1309. https://doi.org/10.3390/land13081309
Khosravani P, Baghernejad M, Taghizadeh-Mehrjardi R, Mousavi SR, Moosavi AA, Fallah Shamsi SR, Shokati H, Kebonye NM, Scholten T. Assessing the Role of Environmental Covariates and Pixel Size in Soil Property Prediction: A Comparative Study of Various Areas in Southwest Iran. Land. 2024; 13(8):1309. https://doi.org/10.3390/land13081309
Chicago/Turabian StyleKhosravani, Pegah, Majid Baghernejad, Ruhollah Taghizadeh-Mehrjardi, Seyed Roohollah Mousavi, Ali Akbar Moosavi, Seyed Rashid Fallah Shamsi, Hadi Shokati, Ndiye M. Kebonye, and Thomas Scholten. 2024. "Assessing the Role of Environmental Covariates and Pixel Size in Soil Property Prediction: A Comparative Study of Various Areas in Southwest Iran" Land 13, no. 8: 1309. https://doi.org/10.3390/land13081309