New technology in irrigation emitters

In the Exudante textile pipeline (TTE) the interaction between the tension of the water in the soil (which is connected with its water content), is the main engine that determines the amount of water that is being exuded by the pipe in its entiretyso that the download speed is not fixed, but that it is related to the speed with which the plants are extracting water stored in the ground throughout the day. This feature represents a conceptual and technological revolution closer to obtaining a perfect and continuous balance between Instant demand for water from the plants and the contribution of water by irrigation systems, which obviously translates into a potential further increase yields and quality, as well as the possibility of a further increase in agronomic efficiency of irrigation.

The idea of using a breathable or exudative pipe is not new: in the last decade have appeared on the market four types of exudative pipe: intensely perforated polyethylene pipe with laser beams, pipe of cellulose in which water is transpirada on the Intermolecular space of the cellulosic network, pipes of recycled rubber that applies water through microtúneles labyrinthic with a porous wall of 2.6 mm thick and exudative textile pipeline (TTE), in which the water is exuded from the plot of a synthetic polyester fibre fabricimpregnated with a porous resin.

The pipe perforated with laser beams did not achieve an impact on the industry of the irrigation pressurized by their high cost and the ease with which the microorificios are obturaban, especially with crystals of fertilizers, which precipitate on the edges of each hole at the end of the irrigationbecause it presented irregularities and edges caused by the laser beam. The pipe of cellulose presented the drawback of its low durability, both by mechanical breakage (little resistant to the traction era) by the effect of the soil microorganisms, which used it as a substrate for food, decomposing it biologically. The pipe of recycled rubber, despite having a long life, also presents problems of sealing by concentration of solids in suspension and by formation of crystals of fertilizers.

The TTE is a fabric of fibres of polyester impregnated of a porous resin, that leaves open spaces of 4 micrones of diameter in the plot of the fabric, the one who is ironinginged to form a line of double wall. When it enters water to pressesure, this line transforms in tube of circular section of 14.5 mm of internal diameter, with a porous wall of 1 mm of thickness. Once that it interrupts the entrance of water, the tube formed empty totally, recovering the material his form of flat line of double wall. The pressesure of operation of the TTE is of 20 to 30 KPA, or was, is an order of inferior magnitude to the pressesure required by the systems of irrigation by dripping. This characteristic determines that the cost of power for presurizar to the water was 10 lower times, as well as the possibility to install systems of irrigation with TTE gravitational. The speed of flow inside the TTE is of character laminar, in the rank of 1,5 to 2,5 m\1s\2, by what the loss of load (loss of pressesure by brush) is a lot lower; this allows to have lateral of irrigation of TTE of until 200 m of long.

The release of the water circulating inside the TTE toward the ground is totally different from the principles that govern the pressurized irrigation systems currently used. In the case of an eyedropper, the water comes out with a pressure equal to atmospheric pressure, with a constant flow, which is regulated by the hydraulic structure of the dropper, generally a maze, a vortex or a combination of both, which are extruded plastic during the construction of the issuer.

The pressure of the water that flows through the interior of the side of irrigation has a fairly broad range (5 to 20 m.c.a), but the download of the dropper is constant. At the TTE, the driving force behind the water out of the textile material through their micropore is the potential difference between the pore water and the water in the soil surrounding itthat is, it's not saturated flow conditions. So at any time or place within the volume of land occupied by the roots of the culture conditions of lack of oxygen are produced. This same situation determines that the water velocity is variable, according to the actual content of water with the ground at any given time.

Changes experienced by the water content of the soil is mainly due to losses by direct evaporation from the surface to the transpiration of crops and the contribution of irrigation water. Variable download of the TTE, whose magnitude is determined by changes in the moisture content of the soil, is automatically adjusted to actual consumption of water derived from evapotranspiration (ET). Thus, for a constant pressure, in the early hours of the day the download of the TTE is very small, because growing ET speed is slow and at noon, the download will reach a maximum value, when the ET is also maximized. Something similar will happen with irrigation at the beginning of the spring, in comparison with the irrigation in the months of highest demand evapotranspirativa of the atmosphere.

On the other hand, constant downloading an eyedropper, within a wide range of pressure, prevents changing the speed of water intake and if you want to apply water to a crop, it is only possible to increase irrigation times. There is the option to increase the pressure of operation with the TTE and or the time of irrigation, which is an easing of the operation which has many benefits.

The TTE presents several features useful for the irrigation of crops accuracy: on the one hand, the fact of being a flexible textile fiber tube allows it to be folded and compressed by the passage of machinery, even during an event of irrigation, without that being damaged. Its tensile strength is of 200 kg and supports pressures of up to 1520 KPa without bursting it. The TTE can be installed and collected from the field with great ease, both its flexibility and its low weight. A 200 m long TTE weighs 4 kg and occupies a volume of 6 liters (approximately), compared with 50 kg of weight and 500 litres of one side of irrigation drip conventional. Polyester fibre and porous resin do not experience physical and chemical modifications with ultraviolet radiation from the Sun, or extremes of temperature in the range from - 20 ° C to 200 ° C.

The sides of polyethylene used for the irrigation drip tend to crack when it freezes water inside; with temperatures above 45 ° C, they suffer from deformations that affect its future operation. Polyethylene polimeriza with UV, becoming a very brittle material, which is avoided, with varying degrees of success, with the addition of "black smoke" as an additive in the manufacture of side pipes for irrigation. Unlike the system of drip irrigation, whose download is constant for a very wide range of pressures of operation, the flexibility of the TTE allows operation with variable pressure, as a way to change your download in as scheduledonly with an increase or reduction in the pressure of operation. This possibility of control of operation allows the producer to adjust irrigation time (with downloads major or minor) to the various activities of the production.