6.3 Water Management

Question 1

When might irrigation be used?

Answer 1

• Area likely to receive very little water through the growing season
• Areas with very free-draining soils

Question 2

Why is it best to establish an irrigation system in a new vineyard as opposed to an establish vineyard?

Answer 2

Can be difficult because of potential disruption to the vineyard in order to lay pipes.

Question 3

What restrictions are there on irrigation use?

Answer 3

Some EU GIs do not permit irrigation or only allow it for emergency situations (establishing young vines, drought that threatens the livelihood of grape growers)

Question 4

Where might water for irrigation come from?

Answer 4

Many sources, such as a nearby river, lake, reservoir or bore-hole

Question 5

What 6 steps can be taken in the vineyard to increase the efficiency of water use?

Answer 5

1. Use of certain water-efficient irrigation systems and techniques combined with better monitoring of water take-up by the vines (e.g. dripper systems and regulated deficit irrigation)
2. use of drought-tolerant grape varieties (e.g. Grenache), and rootstocks (e.g. 140R)
3. Reducing evaporation (e.g. by applying a mulch)
4. Reducing competition (e.g. removing weeds)
5. Increasing humus levels in the soil to improve water retention (e.g. by adding organic matter such as compost)
6. Promoting the growth of vine roots deep into the soil (e.g. through cultivation).

Question 6

Why is it problematic when the irrigation water is high in dissolved solids? What must be done?
Give an example of a type of solid that would be problematic in soil.

Answer 6

• can block sprinkler and drip irrigation systems, therefore needs settling and filtering before use
• e.g. mud

Question 7

Why is it problematic when the irrigation water has a high level of salinity? For which types of irrigation is this most problematic? Where is this a problem?

Answer 7

• This increases salt levels in the soil
• Makes it more difficult for vine roots to take up water
• Vine becomes dehydrated
• Green parts start to wilt and eventually die
• Most problematic for: drip irrigation (salt accumulates at the root zone, rather than being washed deeper into the soil, for example by flood irrigation)
• Australia

Question 8

What is the most common form of irrigation?

Answer 8

Drip irrigation

Question 9

Describe drip irrigation.

Answer 9

• Thin water pipes are laid along each row, typically tied to the lowest trellis wire.
• Drippers are fitted at appropriate intervals.
• • Far enough away from the vines to encourage the roots to grow and seek out water
• • If positioned near vine trunk, roots will simply collect near the trunk where the water falls.

Question 10

Name 4 advantages of drip irrigation.

Answer 10

1. Permit an economic use of water
2. Possible to control water supply to individual rows or blocks of vines, allowing more tailored management of the vineyard and thus potentially higher yields and quality
3. Can also be used to supply fertiliser (liquid fertiliser is added to the water supply); this is called fertigation
4. Can be used on slopes

Question 11

What is fertigation?

Answer 11

When liquid fertiliser is added to the water supply and distributed through drip irrigation

Question 12

Name 4 disadvantages of drip irrigation.

Answer 12

1. Installation costs are relatively high, but maintenance costs are moderate
2. Clean water is required, otherwise the drippers quickly become blocked
3. Drippers can gradually become blocked by algae, bacteria or high levels of minerals and salts; therefore, some maintenance work is usually required
4. Cannot be used in frost protection (aspersion) as the drippers are below the upper parts of the vine.

Question 13

What is flood irrigation? What are the pros and cons?

Answer 13

• Water is stored behind a sluice and at the scheduled time released to flood the vineyard
• Pros: Cheap to install and maintain
• Cons: inefficient as a lot of the water is not taken up by the vine; can also only be used on flat or gently sloping land

Question 14

What is channel irrigation? What are the pros and cons? Name a region that uses this method.

Answer 14

• Water flows down furrows dug between the vine rows
• Pros: More efficient use of water
• Cons: Not suitable where water supply is limited
• Argentina (abundance of water from the Andes)

Question 15

Name 4 methods of irrigation.

Answer 15

1. Drip
2. Flood
3. Channel
4. Sprinklers

Question 16

How are overhead sprinklers used? What are the pros and cons?

Answer 16

• Pump water and shower it over the vineyard
• Pros: Can be used as a method of frost protection
• Cons: Expensive to install and maintain due to high water pressure needed, Use a large amount of water compared to drip irrigation

Question 17

What is regulated deficit irrigation (RDI)?

Answer 17

A system of timing and regulating the amount of irrigation so that the vine is put under mild to moderate water stress for a specified time within the growing season.

Question 18

When is the water deficit of RDI typically scheduled? Why?

Answer 18

• Between fruit set and véraison

- To limit further shoot growth and encourage grape development

Question 19

Where is RDI easiest to carry out? Hardest?

Answer 19

• Easiest: regions with a dry growing season and sandy or loam soils that dry out and can be re-wetted quickly.
• Hardest: regions with heavy rainfall in spring and/or frequent rain in the growing season, and with heavy clay soils that take a long time to dry out

Question 20

What are the benefits of RDI?

Answer 20

• Vine growth and grape development can be better controlled
• Less water can be used
• Improved grape quality (lower yields though)

Question 21

For which color grapes is RDI most beneficial? Why?

Answer 21

• Black grapes
• Can reduce grape size, which increases the proportion of skins to juice, and hence increases the concentration of anthocyanins and tannins, often seen as a sign of quality

Question 22

What can extreme water stress lead to?

Answer 22

Can lead to reduction in yield and quality

Question 23

What is dry farming? Why would a grape grower choose to dry farm?

Answer 23

• Not using irrigation in areas with limited rainfall in the growing season
• Can lead to lower yields but potentially an improvement in grape quality

Question 24

Name a region whose fast-draining soil allows it to produce high quality wines in a rainy, maritime climate.

Answer 24

Medoc

Question 25

What can a grape grower do in a high rainfall region with poor draining soils? When should this be done?

Answer 25

• Install artificial drainage systems

- Best done before vineyard is planted

Question 26

What are the advantages of artificial drainage systems?

Answer 26

• Healthier, better balanced vines
• Better able to ripen grapes consistently
• Aids mechanisation by providing a better surface to drive on

Question 27

What are the disadvantages of artificial drainage systems?

Answer 27

• Costly to install and maintain

Question 28

What are two other ways that water can be regulated in areas with high rainfall in the growing season?

Answer 28

1. Leaving natural vegetation to grow or planting specific crops to provide competition for water, leaving less available for the vine
2. Improving soil structure and removing any plough plans to better regulate water drainage