Double line-source sprinkler system for determining the separate and interactive effects of water and salinity on forage corn

Abstract

The line-source sprinkler system provides a water application pattern which is uniform along the length of the plot and continuously variable across the plot. A double line-source system is described which makes it possible to determine simultaneously the response functions for two factors — salinity and water — and their interaction, on a relatively small area. It is based on two parallel sprinkler lines with overlapping wetting, supplied with water of different quality. The lines are fitted with groups of sprinklers with a range of nozzle sizes to produce different rates of water application. This modified line-source technique has the following advantages: (i) it produces a wide range of water application amounts in combination with a large gradient in water salinity; (ii) different rates of water application are obtained between the two lines within each salinity level; and (iii) on the side of the lines where no overlapping occurs, the use of different rates results in the application of the same amount of water at different distances from the line-source. This is in contrast to the common line-source arrangement, in which the amount of water falling at a given distance from the line is always the same. A study using the double line-source system was carried out to determine the interactive effects of water and salinity on forage corn.