Handbook for Irrigation of Wine Grapes in South Africa

Contents

4.2.2 4.2.3 4.2.4

Micro-sprinklers .................................79 Moveable sprinklers ..........................85 Flood irrigation ...................................87 Subsurface irrigation systems .......91 Maintenance of irrigation systems ....95 Conclusive remarks ......................100 Introduction ....................................102 Comparing rain, river and municipal water quality .................103 Water quality norms ......................105 pH ....................................................105 Nitrogen ...........................................106 Phosphorus .....................................107 Sodium ............................................107 Calcium and magnesium ................109 Bicarbonate and carbonate ............109 Chloride ...........................................110 Fluoride ............................................110 Copper ............................................111 Boron................................................111 Iron ..................................................113 Manganese ......................................113 Zinc ..................................................114 Cadmium .........................................114 Chromium ........................................115 Lead ................................................115 Mercury ...........................................115 Molybdenum ....................................115 Other elements ................................116 Irrigation with saline water ...........116 Quantification and classification of water salinity/sodicity ..................116 Leaching salts from the root zone .....119 Dilution of saline water ....................120 Treatment of saline water ................120 Effect of irrigation systems ..............122 Recommendations ..........................122 On-farm water treatment ...............123 Using treated wastewater for irrigation ...............................................123 Municipal wastewater ......................124 Winery wastewater ..........................127 Conclusive remarks ......................144 Introduction ....................................146 Quantification of grapevine water status ..............................................151 Grapevine water potential ...............151 Carbon isotope discrimination ........152

1 Climate 1.1

Introduction ......................................14 Climate classification ......................15 Climatic indices for viticulture .......19 Growing degree days ........................19 Mean February temperature ..............20 Heliothermal index .............................22 Cool night index ................................23 Comparison between the Köppen- Geiger classification and viticulture- based indices ......................................24 Interaction between climate, wine quality and irrigation ..............24 Climate change ................................26

1.2 1.3

4.3 4.4 4.5

1.3.1 1.3.2 1.3.3 1.3.4 1.3.5

5 Irrigation water quality 5.1

5.2

5.3

1.4

5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 5.3.8 5.3.9

1.5 1.6

Conclusive remarks ........................28 2 The dynamics of water in and around vineyards 2.1 Introduction ......................................30 2.2 The hydrological cycle ....................32 2.3 The water balance in vineyards ........33 2.4 Evapotranspiration ..........................35 2.4.1 Evaporation from the soil ...................35 2.4.1.1 Factors that affect evaporation ..........36 2.4.2 Transpiration ......................................41 2.4.2.1 Factors that affect transpiration .........41 2.4.2.1.1 Viticultural aspects ............................41 2.4.2.1.2 Edaphic factors .................................45 2.4.3 Effect of wetted soil volume on evapotranspiration .............................47 2.5 Conclusive remarks ........................53 3 Water related soil properties 3.1 Introduction ......................................54 3.2 Texture ..............................................54 3.3 Bulk density .....................................59 3.4 Water content ...................................59 3.5 Matric potential ................................60 3.6 Soil water characteristic curves .......60 3.7 Water holding capacity ...................63 3.8 Infiltration rate .................................65 3.9 Permeability .....................................66 3.10 Hydraulic conductivity ....................68 3.11 Conclusive remarks ........................71 4 Irrigation systems 4.1 Introduction ......................................72 4.2 Surface irrigation systems .............74 4.2.1 Drip ....................................................74

5.3.10 5.3.11 5.3.12 5.3.13 5.3.14 5.3.15 5.3.16 5.3.17 5.3.18 5.3.19

5.4

5.4.1

5.4.2 5.4.3 5.4.4 5.4.5 5.4.6

5.5 5.6

5.6.1 5.6.2

5.7

6 Grapevine water status 6.1

6.2

6.2.1 6.2.2

12 IRRIGATION OF WINE GRAPES