Micro-irrigation

Micro-irrigation consists in administering small volumes of water to the soil, in discrete points located near the root system, at short intervals of time (one or more days).

Aimpianto di microirrigazione it consists of a dense network of pipes (drip lines, on which the dispensing devices are inserted) arranged in the area to be irrigated and fed by a collector.

 

 

One of the most important needs that modern irrigation must meet is to ensure high productivity or a high quality standard, in the case of valuable crops. This generally means containing plant costs and saving water resources, reducing manpower and increasing automation.

From the point of view of the economy of resources, the interest is therefore aimed at systems capable of reducing both water and energy consumption, necessary to supply irrigation water, by adopting irrigation systems with low water consumption for achieve maximum efficiency.

Among the irrigation systems, the drip irrigation technique is the one that allows to optimize more than all the irrigation consumptions. Drip irrigation is a highly efficient irrigation method, which allows water savings of approximately 50 %-60% compared to traditional irrigation methods, as it allows to administer the water volume strictly necessary for the needs of the plants in the area explored by the roots, avoiding waste. It follows that for the same amount of available water resources, it is possible, for example, to expand the surfaces served by 5 %-15% .

 

Advantages and drawbacks of micro-irrigation

There are numerous advantages linked to this irrigation technique, even if it requires particular attention as regards theprogettazione , the control of the water regime of the soil and the prevention of clogging phenomena of the dispensers (through filtration and possible chemical treatment of the water).

 

Advantages

The advantages of micro-irrigation can be summarized in the following points.

• A peculiar feature of micro-irrigation is the modest flow rates delivered in discrete points of the soil surface. The best micro-irrigation systems are designed to provide the water required by the individual plant with a daily delivery of 12 hours or more, with a longer duration than traditional irrigation methods or those by sprinkling that generally serve the entire surface of the land in a relatively short time.
• By means of the micro-irrigation system it is therefore possible to increase the watering times, also reducing any water stress for the plants.
• The lower flow rates supplied, in concomitance with the modest operating pressures required, determine a lower energy and system cost than, for example, irrigation systems by sprinkling. The costs of the plant during the construction phase relating to filters, if any, are reducedimpianti di sollevamento (lower head and therefore power) as well as to the ducts which are generally small in diameter. Therefore, the lower flow rates supplied and the lower operating pressures involve the use of fewer energy and financial resources during the operation of the plant compared to other irrigation methods.
• Possibility of using saline water for irrigation, as it determines a lowering of the salt concentration in the area of maximum root activity, following the maintenance, within predetermined and practically constant values, of the water content in the soil.
• Possibility of exploiting unproductive areas for agricultural purposes in relation to their morphology, as it is possible to install the network on steep slopes (with slopes in any case even higher than 15-20%), which would be difficult to irrigate with other methods, and avoiding expensive accommodation of the soil that would be necessary for traditional irrigation systems such as the groove or submersion system.
• Micro-irrigation systems are a good solution for both heavily clayey and sandy soils. In clayey soils, characterized by low infiltration rates, the modest flow rates delivered completely infiltrate the soil without stagnation or surface flow problems. On the other hand, in sandy soils, characterized by high infiltration speed values, traditional irrigation methods pose problems of irrigation losses due to deep percolation, and therefore the use of the micro-irrigation method can represent a valid alternative, also allowing to reduce waste.
• Effective distribution of fertilizers near the root system of plants. The better control achievable on the distribution of fertilizers and on the timing of this operation allows greater effectiveness of the fertilizers themselves, resulting in limited losses due to percolation and limiting the development of weeds, as the inter-rows between the plants can remain dry.
• Better control of plant diseases.
• Labor savings compared to other irrigation methods in relation to the possibility of automating all or part of the systems, as well as the possibility of irrigation for fertilizing purposes with the same system, as an operation not distinct from irrigation.
• By correctly sizing the micro-irrigation systems, it is also possible to distribute the water uniformly over the entire surface to be irrigated so that all plants receive the same amount of water, thus improving irrigation efficiency. A good uniformity of delivery can determine a uniform production yield, precisely in relation to the fact that each plant is supplied with the right amount of water and nutrients it needs.
• Another advantage attributable to this irrigation system is consequent to the supply of water and nutrients only close to the root system of the plant; the inter-rows between the plants can therefore remain dry and consequently the difficulties associated with the movement of the mechanical means after watering are reduced.
• As already noted, through micro-irrigation it is possible to achieve higher irrigation efficiency values than those achievable with traditional surface irrigation systems or through sprinkler irrigation.

The high values of irrigation efficiency are attributable to the possibility of reducing or eliminating losses due to surface runoff, deep percolation and evaporation from the soil.

 

Disadvantages

The micro-irrigation system has the following main problems.

• The need to use skilled labor for both installation and management.
• During the design phase, greater calculation rigor is required as it can create conditions of water shortages in some parts of the irrigated surface and excess water in others, creating in this case asphyxiated areas near the root system.
• Another drawback of micro-irrigation is linked to the accumulation of solutes that can occur at the edges of the moistened soil, causing difficulties in water absorption by the root system of plants, especially in the case in which water characterized by high salinity values is used.
• Another aspect to consider in the design phase concerns the rapid occlusion of the luminaires (due to the limited dimensions of the relative passage sections). Indeed in relation to the qualità dell'acqua di irrigazione the presence of various physical, chemical and biological components may be found, especially if the water is not properly treated or if it has a considerable hardness: for this reason in a micro-irrigation system it is always necessary to provide for the insertion of a filter or a battery of filters before the water reaches the dripper orifices, to ensure adequate filtration.
• Localized irrigation also requires short shifts and modest watering volumes and therefore difficulties in adapting to situations of water delivery in a shift distribution scheme can be determined (for companies of modest extension), unless this is done, at company level, to create appropriate water reserves for compensation.