SOIL PREPARATION

TABLE OF CONTENTS

1.

INTRODUCTION . .............................................................................. 14

2. SOIL IMPEDIMENTS TO ROOT PENETRATION ...................... 18 2.1 Soil compaction ....................................................................................... 19 2.2 Soil acidity ................................................................................................ 23 2.3 Soil stratification . .................................................................................... 24 2.4 Dense clay in the subsoil ........................................................................ 25 2.5 Hardpans . ................................................................................................ 26 2.5.1 Hard plinthite . ......................................................................................... 26 2.5.2 Carbonate hardpan ................................................................................ 27 2.5.3 Dorbank . .................................................................................................. 28 2.6 Waterlogging . .......................................................................................... 28 2.7 Weathered rock in the subsoil . ............................................................. 30 2.8 Coarse fragments in the soil .................................................................. 30 3. DETECTION OF ROOT IMPEDIMENTS ...................................... 34 3.1 Soil inspection and sampling ................................................................. 34 3.2 Soil physical parameters ........................................................................ 35 4. ROOT RESPONSE TO SOIL CONDITIONS ................................ 46 4.1 Root studies ............................................................................................. 49 4.2 Root pruning ............................................................................................ 54 5. SPECIAL SOIL PREPARATION STRUCTURES ............................. 60 5.1 Ridges ....................................................................................................... 60 5.1.1 Soils considered for ridging ................................................................... 60 5.1.2 Construction of ridges ............................................................................ 61 5.1.3 Grapevine performance on ridges ........................................................ 63 5.1.4 Vineyard practices adapted to ridging ................................................. 66 5.2 Terraces .................................................................................................... 69 5.3 Plant holes ............................................................................................... 76 6. SOIL DRAINAGE ................................................................................. 86 6.1 Subsurface water .................................................................................... 86 6.2 Scope and causes of waterlogging . ...................................................... 87 6.3 Surface drainage ..................................................................................... 88 6.4 Subsurface drainage ............................................................................... 89 6.4.1 Cut-off drains ........................................................................................... 90 6.4.2 Open ditches . .......................................................................................... 91

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