Trickle irrigation design manual - Part 1

Abstract

In a trickle irrigation scheme, water and nutriment are carried in pipes from the supply and applied directly to the soil around the plant roots. Water is applied at low rates, but frequently, to keep the soil around the roots at or near field capacity. Trickle irrigation can therefore overcome moisture stress as a limitation to plant production, and at the same time provide a most efficient method of applying water and nutriment. Trickle irrigation was first used in glass houses in the 1950's. Its use on field crops had been contemplated for some time, but this became economically possible only after cheap, durable, plastic pipe was produced. Even with this innovation, trickle appeared more expensive than furrow or sprinkler irrigation, in areas where the conventional methods were working successfully. Thus ,trickle irrigation was introduced to the field, not as an alternative to conventional irrigation, but rather as a replacement where conventional methods were not practicable. The Arava desert in Israel was such an area; the climate was very suitable for growing winter vegetables (high- priced off season crops), but it had sandy soils and saline irrigation water (approximately 3000 μmho/cm electrical conductivity). Both furrow and sprinkler irrigation were therefore, unsuitable and an early form of trickle irrigation was introduced, the anticipated high costs being offset by the value of the off- season crops. This was the beginning of developmental work carried out in Israel , and the early work during the 1960's concentrated at first on the desert regions where conventional irrigation was not feasible. This work involved underground trickle (subirrigation), but surface application was found to be simpler and better. The very encouraging results of the Israelis aroused interest in trickle irrigation throughout many countries. In some of the more recent work in Israel and certainly in countries like Australia and New Zealand, trickle irrigation has outstripped its initial role of only being used when conventional methods were not possible. It is now also viewed as an alternative to furrow and sprinkler irrigation for row- crops and orchards. This very condensed evolution of trickle irrigation has been given for one express purpose: to make the reader aware that much of the early work done comparing trickle irrigation with conventional methods showed quite a spectacular advantage to trickle, but it was done in areas where conventional methods were known to give poor results. Extrapolation of the spectacular results to areas where conventional methods are suitable and efficient , will not necessarily be valid.