Image Number 2 for United States Patent #4928427.
A hollow, cellulose acetate fiber having a wall permeable to water is formed into a coil of constant dimensions. The coil is placed at the root level of the plants to be irrigated. Where the plants are spaced at intervals (as opposed to being immediately adjacent) a number of coil turns are positioned at the plant location and the coil stretched out between plant locations. In this manner, irrigation is concentrated at the plant and minimized in the intervening distance. Consequently, even though the coil is of constant dimensions and porosity, the quantity of water dispensed can be varied as desired. Similarly the spacing between parallel coils can be varied. This spacing variation is desirable where the pressure of the water varies because of height changes, on a slope for example. The subterraneon watering by coil has an additional beneficial effect because the roots of the plants tend to concentrate within the turns of the coil so as to become anchored thereto. This minimizes errosion of the soil around the plants whether caused by water or wind.