Manual of techniques for sustainable mountain viticulture Josep Lluís Pérez Verdú

If the gradient decreases along the terraces then the slope gradient will also have to decrease to keep

the height constant. Therefore, the horizontal ledge of the slope (distance between two consecutive

terraces) will increase. With this new geometry, it may be of interest to continue planting on the terra-

ce or change from the terrace to the slope. Depending on the natural gradient and on the extent of the

lengthways variations of the slope, the optimum will be different. To obtain a precise result, a 3D model

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Chart 4.1 Comparison between slope and terrace planting with constant natural gradient

Theoretic ELA: effective leaf area of all stock planted in 1 ha; calculated for shoots of 0.14 m

2

of ELA with an average space

between shoots of 7 cm.

(1) The limiting factor is the horizontal ledge of the slope (parameter p in Figure 2.2), which must be over 0.6 m so that the

ring of the upper terrace does not interfere with passing along the lower terrace (with a sufficient gap). This prevents the use

of slopes with a higher gradient. 

(2) The limiting factor is the height of the slope (maximum 1.5 m), which prevents more gentle gradient slopes from being used.

Where the height of the slope is limited to 2 m, the resulting ELA increases to the values of the lower row.

Natural slope (%)

20

30

40

50

60

Terrace width (m)

1.3

1.3

1.3

1.3

1.3

Slope gradient (º)

32

43

51

58

62

Slope height (m)

0.38

0.57

0.77

0.95

1.15

Slope length (m)

0.7

0.8

1.0

1.1

1.3

No. of terraces per ha

52

52

52

52

52

Theoretic ELA (m

2

/ha)(1)

24,504

24,504

24,504

24,504

24,504

Terrace width (m)

1.3

1.3

1.3

1.3

1.3

Slope gradient (º)

14

22

32

42

52

Slope height (m)

1.31

1.51

1.44

1.46

1.47

Slope length (m)

5.4

4.0

2.7

2.2

1.9

No. of terraces per ha

15

19

27

34

40

Theoretic ELA (m

2

/ha)(2)

18,371

17,796

16,774

16,605

16,920

Theoretic ELA 

19,757

19,036

18,629

18,680

18,856

(slope height <2 m)

Circular

plantation 

on terrace 

Double vine

training

plantation 

on slope

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must be prepared to introduce the topography of the land and the design conditions of the terraces.

However, certain illustrative criteria can be established based on a 2D model:

•

If the average gradient of the land is only slightly less than the maximum (e.g. up to 33% less), all

the vineyard should be planted on the terrace.

•

If the average gradient of the land is much less than the maximum (e.g. up to 66% less), all the

vineyard should be planted on the slope. 

•

In intermediate cases, planting should be started on the terrace and the slope then used at the

point where the vineyard develops, which will depend on the average gradient: the further away

the average gradient from the maximum, the earlier planting should be changed to the slope. 

In all cases, planting on slopes makes viticulture work more difficult:

•

Precise irrigation of intermediate stock (that is not on the terrace but on the slope) is more com-

plicated because it is on a gradient. 

•

Access to intermediate stock may require climbing the slope on foot. Where the slope gradient

exceeds 30-35%, steps must be installed.

It also has advantages, however:

•

The height of the slopes is greater and, therefore, fewer terraces are required. 

•

Double vine training is cheaper than ring vine training. 

In general, it is only wise to plant on slopes when the ELA gain is significant (e.g. over 15%), although

this will depend on the criteria of each vine grower. 

One way of making slope growing easier is to plant only the end two stocks on the terraces and leave

the liana plant to develop its production branch along the slope with no intermediate stock. To do so,

Mas Martinet is carrying out experiments in order to answer two questions: 

•

Is it possible to accelerate plant growth to form the entire production branch in fewer years through

irrigation? 

•

How does the grape quality vary as the shoots grow further away from the stock? 

The results of these experiments are not yet available. 

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To show the increase in productivity achieved by combining the terracing techniques with those of

vigour control, Chart 4.2 compares the soil area required to produce 10,000 kg of grapes (equivalent

to around 8,600 bottles of wine) for three forms of cultivation: 

•

Conventional terraces with the following characteristics: 

- Terrace width: 2.3 m (2 rows of stock on each terrace).

- Slope gradient: 45º (100%).

- Formation: cordon royat.

•

Mas Martinet terraces and ring vine training on the terrace.

•

Mas Martinet terraces and double vine training on the slope.

In al cases, the natural gradient of the land remained constant at 40%.

As shown by experience, the real ELA is seen to be 65% its theoretic value (see Section 3.4). This also

occurs in conventional plantations, given that some stock is not feasible and other does not reach the

expected ELA. 

In line with Chart 4.1, ring vine training provides the best results. Somewhat more than 1 ha of land is

required to produce 10,000 kg of quality grapes. Conventional planting has a lower productivity and

requires more than 3 ha of land.

Note that, if 6,000 kg/ha are collected in a conventional plantation like the one considered, the resul-

ting production per m

2

of ELA is 1.3 kg, which is very high for preparing a quality wine that can withs-

tanding a good ageing process. The significant parameter is not production per ha, as regulations are

often limited to, but production per m

2

of ELA truly developed on productive stock.

In other words, for each plot, variety and weather, etc. the optimum ratio between ELA and the pro-

duction of a quality grape can be assessed, although there is no optimum ratio per ha. As explained

in the previous sections, it is worth noting that production is not linked to the number of shoots but

to the ELA. The number of shoots depends on the vigour of the stock in order to obtain grapes with

the appropriate morphology for their quality. 

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