Introduction
Materials and methods
Description of the study area
Data collecting and processing
Data analyses
Results
Distribution of soil salinity in different landforms, land uses, soil types and soil texture
Soil depths (cm) | YRD | The south sub-delta | The north sub-delta | ||||||
---|---|---|---|---|---|---|---|---|---|
Mean ± S.E. | Min | Max | Mean ± S.E. | Min | Max | Mean ± S.E. | Min | Max | |
0–30 | 2.31 ± 0.09 | 0.11 | 10.5 | 2.35 ± 0.10 | 0.13 | 10.5 | 2.16 ± 0.18 | 0.11 | 9.86 |
0–10 | 2.83 ± 0.19 | 0.11 | 10.5 | 2.94 ± 0.21 | 0.13 | 10.5 | 2.36 ± 0.45 | 0.11 | 9.86 |
10–20 | 2.05 ± 0.11 | 0.13 | 5.99 | 2.07 ± 0.13 | 0.13 | 5.99 | 2.00 ± 0.21 | 0.15 | 5.14 |
20–30 | 2.05 ± 0.12 | 0.15 | 8.27 | 2.04 ± 0.14 | 0.15 | 8.27 | 2.12 ± 0.22 | 0.27 | 5.58 |
Geographical factors | Subclass of geographical factors | Observations | Soil depths (cm) | |||
---|---|---|---|---|---|---|
0–30 | 0–10 | 10–20 | 20–30 | |||
Landform | Coastal low-lying plain | 49 | 3.27 ± 0.15 | 4.11 ± 0.34 | 2.89 ± 0.19 | 2.81 ± 0.19 |
Tidal flats and salt marsh | 7 | 2.92 ± 0.25 | 3.58 ± 0.60 | 2.63 ± 0.26 | 2.57 ± 0.27 | |
Low-lying drainage basin | 27 | 1.78 ± 0.16 | 2.20 ± 0.37 | 1.70 ± 0.25 | 1.44 ± 0.19 | |
Isolated depression | 13 | 1.60 ± 0.16 | 1.65 ± 0.34 | 1.48 ± 0.25 | 1.67 ± 0.29 | |
Fluvial uplands | 8 | 1.75 ± 0.36 | 1.74 ± 0.81 | 1.69 ± 0.54 | 1.84 ± 0.57 | |
Flood plain | 46 | 1.82 ± 0.15 | 2.27 ± 0.32 | 1.51 ± 0.18 | 1.68 ± 0.26 | |
Land use | Meadow | 46 | 1.81 ± 0.12 | 2.04 ± 0.27 | 1.65 ± 0.16 | 1.75 ± 0.20 |
Shrub | 31 | 3.05 ± 0.23 | 3.76 ± 0.55 | 2.75 ± 0.30 | 2.65 ± 0.28 | |
Farmland | 25 | 1.14 ± 0.12 | 1.39 ± 0.27 | 1.00 ± 0.17 | 1.04 ± 0.18 | |
Forest | 5 | 0.90 ± 0.34 | 1.07 ± 0.84 | 0.94 ± 0.61 | 0.69 ± 0.38 | |
Salt marsh | 43 | 3.17 ± 0.13 | 4.06 ± 0.24 | 2.73 ± 0.16 | 2.70 ± 0.21 | |
Soil type | Gleyic Solonchaks | 107 | 2.61 ± 0.10 | 3.20 ± 0.23 | 2.32 ± 0.14 | 2.32 ± 0.15 |
Calcaric Fluvisols | 27 | 1.86 ± 0.17 | 2.25 ± 0.38 | 1.65 ± 0.24 | 1.66 ± 0.26 | |
Salic Fluvisols | 16 | 1.09 ± 0.13 | 1.37 ± 0.31 | 0.95 ± 0.15 | 0.95 ± 0.15 | |
Soil texture | Sandy clay loam | 21 | 2.08 ± 0.22 | 2.54 ± 0.53 | 1.86 ± 0.28 | 1.84 ± 0.29 |
Sandy loam | 110 | 2.41 ± 0.10 | 2.98 ± 0.22 | 2.13 ± 0.13 | 2.12 ± 0.15 | |
Clay | 5 | 3.08 ± 0.58 | 4.57 ± 1.18 | 2.62 ± 0.84 | 2.05 ± 0.47 | |
Clayey loam | 5 | 2.20 ± 0.54 | 2.30 ± 1.24 | 1.94 ± 0.84 | 2.37 ± 0.90 | |
Silty clay | 9 | 1.45 ± 0.19 | 1.41 ± 0.40 | 1.42 ± 0.27 | 1.53 ± 0.34 |
Soil depths (cm) |
F value (Cedfeldt et al. 2000) |
P value | |
---|---|---|---|
Soil type | 0–30 | 19.58 (2,447) | 0.00* |
0–10 | 5.91 (2,147) | 0.00* | |
10–20 | 9.09 (2,147) | 0.00* | |
20–30 | 7.52 (2,147) | 0.00* | |
Soil texture | 0–30 | 2.50 (4,445) | 0.04* |
0–10 | 1.59 (4,145) | 0.18 | |
10–20 | 0.79 (4,145) | 0.54 | |
20–30 | 0.50 (4,145) | 0.74 | |
Landform | 0–30 | 16.26 (5,444) | 0.00* |
0–10 | 6.08 (5,144) | 0.00* | |
10–20 | 7.55 (5,144) | 0.00* | |
20–30 | 4.93 (5,144) | 0.00* | |
Land use | 0–30 | 30.17 (4,445) | 0.00* |
0–10 | 11.48 (4,145) | 0.00* | |
10–20 | 13.30 (4,145) | 0.00* | |
20–30 | 9.32 (4,145) | 0.00* | |
Locations | 0–30 | 0.37 (4,145) | 0.69 |
0–10 | 0.72 (2,297) | 0.49 | |
10–20 | 0.03 (2,297) | 0.98 | |
20–30 | 0.03 (2,297) | 0.97 |
The spatial distribution characteristics of soil salinity in the YRD
Soil depth (cm) | 0–10 | 10–20 | 20–30 | |
---|---|---|---|---|
0–10 | ||||
Pearson correlation | 1 | 0.865** | 0.740** | |
Sig (tow-tailed) | 0.000 | 0.000 | ||
N
| 150 | 150 | 150 | |
10–20 | ||||
Pearson correlation | 0.865** | 1 | 0.876** | |
Sig (tow-tailed) | 0.000 | 0.000 | ||
N
| 150 | 150 | 150 | |
20–30 | ||||
Pearson correlation | 0.740** | 0.876** | 1 | |
Sig (tow-tailed) | 0.000 | 0.000 | ||
N
| 150 | 150 | 150 |