Fig. 1.
Location map of the study area showing soil sampling points.
Fig. 2.
PCA of the physicochemical soil parameters of Beni Moussa irrigated perimeter. PCA, principal component analysis.
Table 1.
Descriptive statistics for soil properties at 0–20 cm depth in the study area.
| Soil parameter | Descriptive statistics | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Unit | N | Mean | Max | Min | SD | Variance | Skewness | Kurtosis | |
| Saturated hydraulic conductivity | mm · h−1 | 70 | 380.68 | 679.06 | 32.60 | 147.61 | 21,791.200 | 0.852 | –0.112 |
| Bulk density | g · cm−1 | 70 | 0.82 | 1.43 | 1.17 | 0.13 | 0.019 | –0.437 | 0.219 |
| Porosity | (%) | 70 | 45.00 | 68.53 | 54.60 | 5.26 | 27.699 | 0.437 | 0.219 |
| Water content | (%) | 70 | 0.74 | 49.39 | 18.88 | 7.96 | 63.393 | 0.844 | 2.695 |
| Water | −log[H+] | 70 | 7.06 | 8.64 | 7.84 | 0.41 | 0.171 | –0.123 | –0.926 |
| Electrical conductivity | μS · cm−1 | 70 | 24.30 | 1414.00 | 289.65 | 293.78 | 86,309.040 | 1.884 | 3.568 |
| Total dissolved solids | mg · 1−1 | 70 | 11.87 | 750.00 | 171.75 | 168.34 | 28,339.940 | 1.908 | 3.826 |
| Organic matter | (%) | 70 | 2.53 | 27.98 | 9.72 | 4.12 | 17.047 | 1.869 | 5.996 |
| CaCO3 | (%) | 70 | 1.50 | 16.20 | 5.63 | 2.39 | 5.736 | 1.869 | 5.996 |
| Clay | (%) | 70 | 7.00 | 61.30 | 38.89 | 14.09 | 198.600 | –0.775 | –0.440 |
| Silt | (%) | 70 | 13.00 | 81.26 | 41.47 | 15.03 | 226.135 | 0.662 | 0.266 |
| Sand | (%) | 70 | 2.25 | 34.85 | 17.25 | 6.11 | 37.406 | 0.670 | 0.883 |
Table 2.
Pearson correlation analysis of soil variables in the study area.
| Soil parameter | Correlations | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Clay | Silt | Sand | Organic carbon | pH H2O | Water content | Porosity | Bulk density | Saturated hydraulic conductivity | |
| Clay | 1 | ||||||||
| Silt | –0.906** | 1 | |||||||
| Sand | –0.022 | –0.355** | 1 | ||||||
| Organic carbon | 0.168 | –0.064 | –0.179 | 1 | |||||
| pH H2O | –0.045 | –0.018 | 0.087 | –0.429** | 1 | ||||
| Water content | –0.124 | 0.040 | 0.249* | –0.225 | 0.314** | 1 | |||
| Porosity | –0.089 | –0.118 | 0.455** | 0.015 | –0.079 | 0.224 | 1 | ||
| Bulk density | 0.089 | 0.118 | –0.455** | –0.015 | 0.079 | –0.224 | –1.000** | 1 | |
| Saturated hydraulic conductivity | –0.295* | 0.264* | 0.068 | –0.040 | 0.069 | 0.333** | –0.117 | 0.117 | 1 |
Table 3.
Best suited variogram models and Moran’s I.
| Soil parameter | Semi-variogram model | Nugget C0 | Sill (C0 + C) | N/S [%] | Range [m] | Moran’s I |
|---|---|---|---|---|---|---|
| pH (water) | Spherical | 0.0196 | 98.67 | 77.47 | 23,943.08 | 0.097 |
| Electrical conductivity | Spherical | 0.0015 | 32.25 | 20.27 | 36,857.24 | –0.168 |
| CaCO3 | Spherical | 0.0164 | 125.99 | 71.28 | 38,431.47 | 0.188 |
| Organic carbon | Spherical | 0.0095 | 138.88 | 62.95 | 20,929.04 | –0.184 |
| Sand | Spherical | 0.0016 | 98.44 | 52.48 | 5738.90 | 0.070 |
| Clay | Spherical | 0.0183 | 68.80 | 86.05 | 37,250.14 | –0.002 |
| Silt | Spherical | 0.0038 | 22.60 | 48.89 | 5939.51 | –0.163 |
| Porosity | Spherical | 0.0192 | 168.97 | 41.56 | 10,851.70 | 0.231 |
| Saturated hydraulic conductivity | Spherical | 0.0042 | 114.51 | 28.70 | 5838.28 | 0.201 |
| Organic matter | Spherical | 0.0147 | 121.40 | 56.65 | 5215.99 | –0.162 |
| pH (KCl) | Spherical | 0.0031 | 92.53 | 53.84 | 20,617.10 | 0.219 |
| Total dissolved solids | Spherical | 0.0172 | 5.37 | 88.92 | 11,538.66 | –0.140 |
| Water content | Exponential | 0.0010 | 0.85 | 30.59 | 23,207.25 | –0.220 |
| Bulk density | Spherical | 0.0112 | 151.38 | 36.13 | 39,548.55 | 0.296 |
Table 4.
Cross-validation metrics for 14 soil parameters.
| Soil parameter | Mean error | Root mean square error RMSE | Root mean square standardised error RMSSE | Average standard error |
|---|---|---|---|---|
| pH (water) | –8.98E–07 | 0.0086 | 0.8049 | 0.0107 |
| Electrical conductivity | –0.00026496 | 5.7996 | 0.7820 | 7.4201 |
| CaCO3 | –0.000938 | 0.0183 | 0.8570 | 0.0214 |
| Organic carbon | –0.000006 | 0.0399 | 0.7782 | 0.0511 |
| Sand | –0.000056 | 0.1373 | 0.8078 | 0.1702 |
| Clay | –0.000201 | 0.4317 | 0.8036 | 0.5378 |
| Silt | 0.000049 | 0.3668 | 0.3026 | 1.2130 |
| Porosity | 0.000015 | 0.1693 | 0.6288 | 0.2693 |
| Saturated hydraulic conductivity | 0.000110 | 4.8441 | 0.8058 | 6.0197 |
| Organic matter | –0.000103 | 0.0687 | 0.7782 | 0.0884 |
| pH (KCl) | –0.000705 | 0.0086 | 0.8049 | 0.0107 |
| Total dissolved solids | 0.000001 | 0.1381 | 0.8409 | 0.1649 |
| △θ | –0.000015 | 0.0141 | 0.7615 | 0.0186 |
| Bulk density | –1.68E–07 | 0.0032 | 0.8349 | 0.0039 |
Fig. 3.
Fitted semi-variogram for the selected soil property: A – CaCO3, B – electrical conductivity, C – organic carbon, D – bulk density, E – stability, F – clay, G – silt, H – sand, I – moisture using the exponential model, J – Saturated hydraulic conductivity, K – organic matter, L – pH water, M – pH_KCl, N – porosity, and O – total dissolved solids using the spherical model.
Fig. 4.
Kriging maps produced for Beni Moussa irrigated perimeter: (a) – saturated hydraulic conductivity Ks(mm · h−1); (b) – porosity%; (c) – bulk density; (d) – moisture%, (e) – pH water; (f) – electrical-conductivity (μs · cm−1); (g) – clay (%); (h) – sand (%).
Fig. 4.
Kriging maps produced for Beni Moussa irrigated perimeter: (i) – silt (%); (j) – carbonate de calcium CaCO3 (%); (k) – organic matter (%); (l) – organic carbon. (m) – total dissolved solids and (n) – pHKcl.