Drip irrigation is an irrigation method that slowly applies water to plants, both depositing water on the surface of the ground surrounding the plant or directly onto the root area. The goal is to reduce the amount of water as much as possible, applying on the basis of the daily requirements and best exploiting use of the water introduced with the irrigation through the movements of the solution circulating in the ground. With drip irrigation, small quantities of water are distributed on a localised basis, which irrigate a strip of soil along a row of plants. By percolating into the ground, the water can even spread laterally, creating a moist underground strip close to the root system, possibly uniformly. To that end, distributing devices called drippers can be used. Surface drip irrigation uses dripper distribution lines to distribute water to the surface of the ground near the plants, i.e., pipes with drippers inserted into them, generally on the ground along a row of plants. The drippers can be “normal” or “self-compensating”. Self-compensating drippers maintain the same output pressure at different inlet water pressures, even for very long dripper distribution systems, since the dripper contains a basic labyrinth, along with an elastic membrane that self regulates the water flow rate to keep it constant even when the pressure varies along the pipe. They can be developed even along rows of 450-500 metres. The subsurface micro-irrigation system is a slightly different system and provides for the burying of the drippers in a way that the drippers can be found directly in the area of the root system development, facilitating the regular, uniform spread of the water. This also avoids impeding crop work (if necessary) when the pipe is laid on the ground. There are long-lasting drippers (defined as heavy) used mainly in fruit-farms and vineyards which last for the lives of the plants, and temporary drippers (defined as light) used especially for annual crops of annual cycles. The main advantages provided by drip irrigation: greater uniformity of water distribution with less waste; easier operating facility; better preparation for system automation; ability to exploit the maximum potential of fertiliser distribution in the irrigation water (fertigation); greater energy savings; lower soil compacting. The basic concept is the opportunity to apply water frequently, daily or even a few times a day, and considering the plant as a “living being” which gets food (and water) every day in the same way as a human or an animal. It replaces the idea that the ground is a reservoir, and once it has been filled, can satisfy the needs of plants for a longer or shorter time. In fact, for the reasons set out above, micro-irrigation means that the need to keep air in the soil – from which the plant can obtain oxygen – is better served. Generally, it is preferable to water in the early morning, at dawn, to allow the water to percolate and spread out in the root system area, ready to be absorbed at the hottest time of the day from the end of the morning to late afternoon.
