Page 11 - Soil Degradation, Conservation and Remediation

x Contents

1.8 Laws of Sustainable Soil Management .............................................. 37
References................................................................................................... 39

2 Physical Deterioration of Soil .................................................................. 45
2.1 Processes and Types of Physical Deterioration of Soil ...................... 45
2.2 Surface Sealing, Crusting, Hardsetting,
and Compaction (Pc) ......................................................................... 46
2.2.1 Surface Sealing .................................................................... 46
2.2.2 Surface Crusting .................................................................. 48
2.2.3 Soil Compaction .................................................................. 52
2.3 Waterlogging...................................................................................... 57
2.3.1 Causes of Waterlogging....................................................... 58
2.3.2 Effect of Waterlogging......................................................... 59
2.3.3 Control of Waterlogging ...................................................... 59
2.4 Lowering of Groundwater Table ........................................................ 59
2.5 Subsidence of Organic Soils .............................................................. 60
2.6 Desertifi cation .................................................................................... 61
2.6.1 Natural Versus Human-Induced Desertifi cation .................. 62
2.6.2 Convention to Combat Desertifi cation ................................. 63
2.6.3 Mechanism of Human-Induced Desertifi cation ................... 63
References................................................................................................... 65
3 Soil Erosion by Water ............................................................................... 69
3.1 Geological and Accelerated Erosion .................................................. 69
3.2 Causes of Water Erosion .................................................................... 70
3.3 Types of Water Erosion ...................................................................... 70
3.3.1 Splash Erosion ..................................................................... 71
3.3.2 Sheet Erosion....................................................................... 72
3.3.3 Rill Erosion.......................................................................... 74
3.3.4 Gully Erosion....................................................................... 75
3.3.5 Tillage Erosion..................................................................... 77
3.3.6 Landslide/Landslip/Mudfl ow ............................................... 77
3.3.7 Riverbank/Stream Bank Erosion.......................................... 77
3.3.8 Effects of Water Erosion ...................................................... 78
3.3.9 Soil Loss Equations (USLE and RUSLE) ........................... 80
3.3.10 Soil Loss Tolerance Value (T Value) .................................... 83
3.4 Control of Water Erosion ................................................................... 83
3.4.1 Amendments ........................................................................ 84
3.4.2 Cover Crops......................................................................... 84
3.4.3 Conservation Tillage............................................................ 86
3.4.4 Mulching.............................................................................. 88
3.4.5 Contour Cropping................................................................ 89
3.4.6 Strip Cropping ..................................................................... 90
3.4.7 Contour Strip Cropping ....................................................... 90
3.4.8 Sloping Agricultural Land Technology (SALT) .................. 91
3.4.9 Agroforestry......................................................................... 93