DRIP IRRIGATION FOR TABLE GRAPES

Table grapes — a product of the “Bel Paese”

Table grapes differ from wine grapes in several respects. Their full ripening occurs when the sugars in the berries have replaced the organic acids, whereas wine grapes are harvested while still retaining a marked acidity, essential for must fermentation, winemaking, and subsequent ageing.

Thanks to the work of skilled professionals and agronomists who have devoted time and dedication to the development of this crop, table-grape production today represents a significant source of income. Regions such as Puglia, Sicily and Basilicata make Italy the European leader in table-grape production.

Nutritional requirements

Table-grape vines have specific annual nutrient needs and, during the growing season, remove from the soil approximately: 51 kg/ha of nitrogen, 10 kg/ha of phosphorus (P₂O₅), 27 kg/ha of potassium oxide (K₂O), 108 kg/ha of calcium oxide (CaO), and 14 kg/ha of magnesium oxide (MgO).

The use of biostimulants has produced encouraging results in terms of bunch weight, uniformity, skin colour, and soluble-solids content typical of the “Italia” cultivar. Irrigation water itself can represent an additional, valuable source of mineral elements for table grapes.

Even water of good or excellent quality may contain concentrations of nitrogen, potassium, calcium, magnesium, sulphur, chlorine, and sodium that significantly contribute to the plant’s nutritional balance — and, for certain microelements, can even fully satisfy annual requirements.

The best irrigation for table grapes

The most suitable irrigation method for this crop is drip irrigation, since the vine has high water demands during the central part of the vegetative season (June–July), with an indicative daily consumption of 20–40 litres per plant per day.

The dripline (standard or pressure-compensating) is laid along the row with different emitter spacings and flow rates depending on soil type and crop requirements.

In many cases, it is suspended from the support wire of the overhead trellis using support hooks, in order to avoid agronomic interference and to facilitate soil operations.

Appropriate filtration units (selected by type and micron size), fertiliser-injection devices (fertrigation systems), and soil-moisture sensors are also recommended, enabling technicians to schedule future irrigation events based on the soil’s actual water availability.