D1: Managing Nutrients and water 10

Question 1

Soil health is the ability of the soil to support the vine, enabling it to grow and produce fruit. it’s related to:

Answer 1

1) The structure of the soil: good drainage, sufficient water- holding capacity, sufficient oxygen, the ability to resist erosion and to allow the roots to penetrate to sufficient depth
2) The amount of organic matter and humus in the soil: decomposing organic matter supplies nutrients and humus improves the structure of the soil and its water holding capacity
3) the number of living organisms: earthworms and microbes break down organic matter into humus and inorganic nutrients that are accessible to the vine
4) the total amount of available nutrients that the vine needs to grow successfully

Question 2

Poor soil health can lead to problems with the availability and uptake of nutrients and water in the soil, and hence poor vine growth and ripening.

Answer 2

The soil may be tested at the begin of the establishing vineyard and then annually so that corrective measures can be taken: improve the structure of the soil, (by ex adding compost) or by addjusting nutrients

Question 3

The right balance of nitrogen, phosphorus and potassium as well as many other nutrients is essential for healthy vine growth and the ripening of grapes.

Answer 3

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Question 4

Weeds:

Answer 4

1) unwanted plants that can compete with the vine for nutrients (and water)
2) the removal of weeds can be desirable for additional reasons: Bare moist soils are best at absorbing heat during the day and the heat they release at night reduces frost risk

• • so weeds as well as cover crops and mulches can therefore increase frost risk
• • also some weeds hamper the passage of machinery and personnel (stinging nettles, brambles)

Question 5

Fertilisers may be added before planting to help the growth of young vines, they may also be applied to established vineyards to correct any detected nutrient deficiencies. however excessive addition of fertilisers may lead to excess vigour and an unbalanced vine.

Answer 5

Fertilisers may be orgnic or mineral.

Question 6

Organic fertilisers:

Answer 6

1) derived from fresh or composted plant or animal material, such as manure (mest) or slurry (drijvende mest)
2) cover crops can be grown and mown into the soil to decompose and provide nutrients (green manure)

3) Organic fertilisers are cheap or often free: some are high in humus and therefore good for soil structure and water retention
* as the nutrients are in an organic form, they provide nutrition for soil organisms (promoting living matter in the soil)

4) These fertilisers needs to be broken down by the organic organisms and require incorporation (opname) into the soil which requires labour

5) an advantage is that the nutrients become available to the vine gradually
* a disadvantage is that they can be bulky and therefore expensive to transport and spread

Question 7

Mineral fertilisers:

Answer 7

1) extracted from the ground or chemically manufactured

2) they provide a single nutrient or several nutrients
* Therefore, they can be more tailored than organic fertilisers

3) the nutrients are already in an inorganic form so can be directly taken up by the vine
4) it is no benefit for the living soil organisms
5) often more expensive than organic fertilisersto purchase, but as they are more concentrated, much cheaper to transport and distribute

Question 8

What is cultivation?

Answer 8

method of weed control that involves ploughin the soil to cut or disturb the weeds root system

Question 9

Advantages of cultivation:

Answer 9

1) no chemicals used so good for organic and biodynamic viticulture
2) it enables fertilisers and, where relevant, mown cover crops to be incorporated into the soil at the same time as removing weeds

Question 10

Disadvantages of cultivation:

Answer 10

1) repeated cultivation can damage the soil’s structure and ecology, due to the breakdown of matter and destruction of habitats
2) its costly as it requires both skilled labour and machinery
3) disturbing the soil burries seeds, thus encouraging the weeds to grow back
4) it can increase vine vigour too much as there is no competition for water or nutrients (can be an advantage in some regions)

Question 11

Herbicides are chemical sprays that kill weeds. there are three types of herbicides:

Answer 11

1) pre-emerged herbicides are sprayed before weeds establish
* they persist in the surface layers of the soil, but are absorbed by the weeds’ roots and inhibit germination of young seedlings

2) contact herbicides are sprayed on established weeds and kill the green parts of the weed they contact
3) systemic herbicides are sprayed on established weeds and are taken up by the leaves. the herbicide travels up and down the weed in the sap and kills the whole plant

Question 12

Advantages of herbicides:

Answer 12

1) They are cheap in terms of labour and machinery requirements
2) They are highly effective, particularly in the under-row area
3) they are less damaging to the soil structure than cultivation

Question 13

Disadvantages of herbicides:

Answer 13

1) They present the risk of poisoning to the operator, consumer and environment and do not encourage vineyard ecosystems

2) weeds can become resistant and therefore larger doses or different chemicals need to be used
* the routine of use of glyphosate, the most common contact herbicide SA has given grape growers a particular problem with glyphosate resistant ryegrass

3) they can increase vine vigour too much (can be an advantage)
4) theyre not allowed in organic and biodynamic viticulture

Question 14

Another method of weed control is to allow anials, such as sheep, to graze in the vineyard. advantages:

Answer 14

1) Can be used in bio or biodynamic viti
2) the animals can provide the vineyards with manure
3) the animals can be a source of meat for humans

Question 15

Disadvantages of grazing animals:

Answer 15

1) the vines need to be trined high or the grazing must be conducted out of growing season, otherwise the animals may eat tge grapes and leaves of the vine
2) the animals need caring fore as they belong to the vineyard owners, so requires labour
3) the animals are often susceptible to vineyard pesticides

Question 16

Cover crops may be grown to supress weeds, but also:

Answer 16

1) improve soil structure
2) compete with the vine for nutrient and water availability in fertile sites
3) manage soil erosion
4) enhance biodiversity
5) provide a surface to drive on

• • ex of cover crops: legumes like beans and clover
• cereals: ryegrass and oats

** you can also leave the natural vegetation to grow in the vineyard. this will enhance biodiversity, but specific cover crops will allow more control

** if ploughed into the soil, the cover crop or natural vegetation can provide organic matter to the soil and in this way fertilise the soil (green manure)

Question 17

Advantages of cover crops:

Answer 17

1) This method does not use any chemicals and increase soil biological activity and biodiversity in the vineyard , so good for organic and biodynamic viti
2) introduces competition nutrients and water (vigour)
3) the provision of a good surface for machinery especially in climates with high annual rainfall

Question 18

Disadvantages cover crops:

Answer 18

1) A reduction in vine vigour (through competition for water and nutrients)
2) the difficulty of mowing the under-row area, particularly near the vine trunks, which has implications on time and labour
3) the unsuitability for steeply-sloping vineyards as they are slippery when wet

Question 19

What is mulching ?

Answer 19

1) spreading of matter onto the vineyard soil to supress the growth of weeds

2) mulches are usually made of biodegradable materials, such as straw or bark chips, that ultimately provide nutrients for the vines
* materials with high nutrient content can be choosen in nutrient poor vineyards

Question 20

advantages of mulching:

Answer 20

1) no chemicals so organic and biody viti
2) it can reduce water evaporation from the soil, which can be advantageous for dry climates
3) it can be a source of nutrients and humus, which provides soil biological activity and good soil structure

Question 21

disadvantages of mulching:

Answer 21

1) tends to be very bulky, so expensive to transport and spread
2) it is only effective if applied in a thick layer, so a lot can be needed
3) it can increase vigour too much as here is no competition for water or nutrients (an advantage in dry regions or low vigour regions)

Question 22

Irrigation:

Answer 22

1) best installed before the vineyard is established to not disturbing the vineyard in order to lay pipes
2) some EU gi’s do not permit irrigation
3) difficulty in sourcing water for irrigation may mean that it cannot be used

Question 23

Sources of water and efficiency of use:

Answer 23

Water for irrigation can come from many sources, such as nearby river, lake, reservoir or bore hole
* water is a precious resource and therefore in many countries water use is tightly regulated

Question 24

For sustainability it is important to increase the efficiency of water use. steps taken in the vineyard includes:

Answer 24

1) use of water efficient irrigation systems and techniques, combined with better monitoring of water take up by the vines (dripper systems and regulated defict irrigation)
2) use of drought tolerant grape varieties (grenache) and rootstocks (140R)
3) reducing evaporation by applying a mulch
4) reducing competition
5) improve humus levels in the soil to improve water retention (adding organic matter such as compost
6) promoting the growth of vine roots deep into the soil (eg through cultivation )

• • water is also a valuable source in the winery, where it is mainly used for cleaning
• • consideration of ways in which this water can be re-used (some may be suitable for irrigation) can also maximise efficiency of water consumption

Question 25

Water quality:

Answer 25

1) water that is high in solids such as mud can block sprinkler and drip irrigation systems and therefore needs settling and filtering before use

2) water that contains high levels of salt (high salinity) can also be problematic (australia)
* this water increases the salt level into the soil and make it more difficult for vine roots to take up water
- – the vine becomes dehydrated, leaves wilt and eventually die

** this is particularly a problem with dripp irrigation (salt accumulates at the roots zone rather than being washed deeper into the soil for example by flood irrigation

Question 26

Ways of irrigation:

Answer 26

1) drip irrigation is the most common
2) thin water pipes are laid along each row (typically tied to the lowest trellis wire
3) fitted at appropriate intervals
4) far enough from the vine to encourage the roots to grow and seek out water (if drippers are installed near the trunk, the roots only takes this water)

Question 27

The key benefits of drip irrigation:

Answer 27

1) They permit an economic use of water
2) it is 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) also be used to apply fertiliser (liquid fertiliser is added to the water supply) this is called fertigation
4) they can be used on slopes

Question 28

Disadvantages of drip irrigation:

Answer 28

1) installation costs are relatively high, but maintenance cost are moderate
2) Clean water is required, otherwise the drippers get stucked
3) if stucked by algae, bacteria or high levels of minerals and salts (maintenance work is required)
4) they cannot be used in frost protection (aspersion) as the drippers are below the upper parts of the vine

Question 29

Flood irrigation:

Answer 29

1) only in areas where there is access to large quanteties of water
2) cheap to install and maintain
3) not efficient as a lot of water is not taken up by the vine
4) it can only be used on flat land or gently sloping land

Question 30

Channel irrigations:

Answer 30

1) similar to flood irrigation
2) the water flows down furrows(voegen) between the vine rows which can help increase efficiency of water use
3) common in argentina because of abundant water from the andes

Question 31

Sprinklers:

Answer 31

1) pump water and shower it over the vineyards
2) expensive to install and maintain due to high water pressures needed and still use a relatively large amount of water compared to drip irrigation
3) they can be used as frost protection (aspersion)

Question 32

The vines requirement for water varies throughout the vine cycle:

Answer 32

1) in dry climates the grape grower can use irrigation to control the water supplied to the vine and therefore put the vine in mild water stress at the appropriate times in the vine cycle
2) plentiful supply of water in spring: encourages the establishment of a large leaf surface area to support the production of high yields of grapes
3) mild waterstress can often be desirable between fruit set and veraison to stop the growth of shoots and encourage grape development and ripening

Question 33

RDI: regulated deficit irrigation:

Answer 33

1) timing and regulating the amount of irrigation
* so that the vine is set under mild to moderate water stress for a specified time within the growing season

2) Easiest in dry regions with adry growing season and sandy or loam soils that dry out and can be rewetted quickly
3) the benefits of rdi is that the vine growth and grape development can be better controlled and that less water can be used

** this type of irrigation is favoured for black varieties as it can reduce grape size, which increases the proportion of skins to juice, increases the concentration of anthocyanins and tannins (often seen as a sign of quality)

4) even if rdi is carried out successfully, the yields can be lower so the grape grower must be confident that any improvement in grape quality will make up for smaller volumes
5) the additional cost (assuming the vineyard already has drip irrigation) is the equipment to monitor and respond to levels of moisture in the soil

Question 34

Dry farming:

Answer 34

The use of no irrigation in regions with low rainfall

** this can lead to lower yields but potentially an improvement of grape quality

Question 35

one of the factors that leads to high quality wines in the medoc is the presence of fast-draining gravel soils in this rainy, maritime climate.

Answer 35

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Question 36

In regions with high rainfall in the growing season, the water available to the vine can also be regulated by:

Answer 36

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 an plough plans to better regulate water drainage