Although simple in its conception, the large-scale use of micro-irrigation has proved practical in the last thirty years in relation to the affirmation on the market of plastic materials .
Since the middle of the last century, various researchers have conducted experiments on various types of surface irrigation and sub-irrigation techniques. The first attempts at a summary sub-irrigation system were made in 1860 by German researchers, who pumped irrigation water into existing underground drainage systems. Later, in the 1920s and 1930s, various types of porous tubes were used by a number of researchers.
Polyethylene pipe
It was in the field of materials science that the decisive step was taken, when polyethylene was produced in a British laboratory in 1935. Polyethylene is produced by high-pressure heating of ethylene monomer gas, a component of natural gas and other fossil fuels. In the early years of its development, only the low density form of polyethylene (PEBD) was known, produced at relatively high pressures (up to 3500 bar).
The discovery of high density polyethylene (HDPE) in 1948, produced at low pressures (20 bar), broadened the field of applications. Polyethylene (PE) has excellent resistance to most chemicals and possesses extraordinary electrical insulation properties.
In 1977 the polyethylene industry introduced a major innovation with the development of a low pressure polyethylene production process, which reduced the cost and increased the quality of polyethylene resins. The development of plastics has continued to progress with the recent introduction of Linear Ultra Low Density Polyethylene (PELLD), which exhibits increased strength and breaking strength.
Polyethylene is a remarkably strong and flexible material with a wide range of physical properties due to the size and arrangement of the ethylene molecules. When specific additives are added to the clear plastic, including antioxidants, stabilizers and carbon black, a durable and economical product for micro-irrigation is created. Large-scale commercial use of micro-irrigation systems began in the late 1960s and early 1970s.
As is understandable, the interest and the spread of micro-irrigation have occurred in areas where water resources for irrigation are limited (Australia, California, Israel). Farmers soon discovered that in many cases they could increase production substantially, while reducing watering volumes by 25% to 50% of the volumes needed using traditional irrigation methods.
