Double-emitter source (DES) for irrigation experiments in salinity and fertilization

A double-emitter source (DES) irrigation system was designed, using trickle instead of sprinkler irrigation. Two trickle laterals and their emitters connected to two tanks of stock solutions are coupled together to form a double-joint lateral. The emitters of the two lines have different and varying discharges to obtain various mixings between the two stock solutions while maintaining constant application rates. The layout produces a sequence of intermediates between maximal and minimal concentrations. The method was tested for a salinity experiment on globe artichoke (Cynara scolymus L.) and a fertilization experiment for amaryllis (Hippeastrum hybrid). Average electrical conductivity (EC) of the fresh and saline laterals was 1.5 and 6.2 dS m^-1, respectively. The N and K concentrations in the stock solution were 13.12 g L^-1 and 9.38 g L^-1, respectively, for a mixed and diluted maximum of 777 and 556 mg L^-1 N and K at the irrigation solution. Artichoke yield declined by 60% due to salinity when EC increased from 1.5 to 6.2 dS m^-1. Hippeastrum bulb diameter and weight increased 35% with high N and low K application. We conclude that the double-emitter source can be used for precise application of varying salts or nutrients in multivariable experiments. Advantages include prevention of canopy wetting by saline water, precise distribution of the factor to be evaluated, and small experimental plots (reducing time, area, and labor requirements).