Irrigation in vineyards, if carried out rationally, is an agricultural practice that can make a considerable contribution to the quality of the production, as has been amply demonstrated in experimental trials. Irrigation needn’t necessarily be limited to arid areas as even in areas that are generally damp, long periods of drought can be a real danger, causing damage to the production both from a quality and quantity aspect. The various aspects connected to irrigation in vineyards have been dealt with by Dr. Salvatore Scicchitano of Irritec & Siplast , during the seminar “La tecnologia italiana nell’irrigazione di qualità in viticoltura”, (Italian Technology in quality irrigation in vineyards) promoted during the “Corso di Tecnica Viticola del Corso di Laurea in Viticoltura ed Enologia” at Bologna University held in Tebano (Faenza) on 8th May 2006. Correct irrigation in vineyards depends on various factors including knowledge of the water retention properties of the soil and recognising the need for water during the various phases of the growth and production cycle so as to be able to intervene immediately and with the correct volume of water, if necessary adopting the technique of controlled water stress, both to correct unbalanced conditions and to correct the components of the grapes.
Considering that the distribution of water resources is becoming an ever-increasing problem on a global scale and considering the high water consumption utilised in agriculture, good practices must be introduced to avoid waste. Subsurface irrigation is probably the best technique as it utilises the water resources in a rational way by taking the water directly to the root level so using a much smaller quantity while being much more efficient as there is no water loss due to evaporation or waste due to wind. Subsurface irrigation also permits a more efficient way of fertigation and it reduces the environmental impact usually associated with this practice, as the fertilisers are released directly onto the root system. Furthermore it effectively combats ferric chlorosis as it provides the means to intervene immediately by distributing iron-chelates directly to the roots. Subsurface irrigation also helps to diminish the growth of spontaneous weeds and fungus diseases because the surrounding vegetation does not receive water from the irrigation system so avoiding the conditions ideal for the growth of cryptogams. Neither must we under-estimate the advantage of being able to work in the vineyard during irrigation with machinery utilised for vine trimming, mechanical pruning and mechanised harvesting, operations that are impossible during irrigation with traditional methods. Furthermore, the fact that the irrigation system is buried in the soil protects it from ultra-violet rays and climatic conditions, guarantees less wear and tear as well as protecting the system from acts of vandalism and improving the aesthetic aspects of the vineyard due to the fact that the entire irrigation system is out of sight.
The main obstacle to the diffusion of this technique is without doubt the problems caused by the intrusion of root tips into the pipes through the emission holes that will eventually obstruct them completely. Over the years many solutions to this problem have been put forward including the adoption of rigid tubes with holes, tubes in polyethylene with the opening and closing of the water exit points determined by the pressure and by porous tubes. In general these solutions have not been successful over a period of time, in hindering the development of root tips. As emphasised by Dr. Salvatore Scicchitano , the solution to the problem has been found in the adoption of a polymeric “container and distributor” that is able to ensure a slow, controlled, continual emission of a weed killer. From a practical point of view, Trifluralin was combined with plastic polymers during the manufacture of the drippers. The quantity of weed killer emitted depends on the initial concentration of the active ingredient, on the shape of the plastic polymer container and on the temperature while the duration of the protection is conditioned by the quantity of the active ingredient released in order to maintain a sufficient concentration in the soil around the emission point in order to block the development and growth of roots. This system was perfected to protect the nuclear waste storage sites from damage caused by the roots of desert plants.
Tests have been carried out to analyse the mechanism that releases the Trifluralin and to assess the duration of the protection. Results have shown that the drippers release 80% of the herbicide in 100 hours at a temperature of 80°C , in 7 years at 30°C and in 34 years at a temperature of 23°C .
From among all the weed-killers available, Trifluralin was chosen because it was considered relatively non-toxic, it is not systematic, it has low solubility in water, it does not move in the soil and only a small quantity is sufficient per hectare. Tests carried out by ISPAVE in Rome, (Istituto Sperimentale per la Patologia Vegetale- Experimental Institute for Vegetable Pathology) have demonstrated that no traces of Trifluralin have been found either in the leaves or the fruit of tomato and courgette plants that were used for testing and above all, the tests demonstrated that the quantity of weed-killer found in the area immediately surrounding the drippers (3 x 5 centimetres ) was between 0.002 and 0.011 mg/kg (ppm) and that beyond this small area of soil there was no trace of the active ingredient. Tests have further proved that the roots of weeds were never present near the drippers, which therefore remained perfectly unblocked and efficient while in the drippers that were not treated with Trifluralin, after only three months, there was a partial presence of roots with a consequent reduction of the effectiveness of the irrigation system.
When planning a system of subsurface irrigation certain factors must be considered such as the depth and the distance between each of the drippers, which must be adequate to provide enough water to dampen the area covered by the root system. In ideal soil conditions, the irrigation pipes should be about 30- 40 centimetres underground while for extremely sandy soil or for stony soil the pipes should be shallower so as to avoid excessive water loss due to percolation in the lower layers of soil. In the case of vineyards where the rows of vines are fairly close together, it is advisable to install the irrigation in the middle of the two rows. The delivery capacity and the distance between the single drippers must be established taking into consideration the characteristics of the soil and the water requirements of the crop in question.
Furthermore it is advisable to install the irrigation system only after the plants have been planted so as to avoid cuts and damage caused by shape mechanical equipment.


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