Concentration Variability of Fertilizers in Pressurized Fertigation System

An experiment was conducted to measure the variability in urea-N and potassium concentration with injection time at different operating pressures. It was done with urea and muret of potash (MOP) for different amounts of fertilizers (10, 16 and 21 kg of urea and 5, 7.5 and 10 kg of MOP) at different operating pressures (1.5, 2.0, 2.5 and 3.0 kg cm-2). Polynomial and exponential forms of empirical equations were developed to determine the concentration of fertilizer in the tank with injection time. In the first half an hour the remaining concentrations of both the fertilizers of different amounts in fertigation tank was less than 40% and in the next one hour the remaining concentration was less than 10%. There was no significant effect of operating pressure on change in fertilizer concentration with injection time. However, higher operating pressure may be used to apply the maximum amount of fertilizer in the beginning of the injection duration. The exponential form of equation is easier in use and also accurate for relating the concentration of fertilizers in fertigation tank with injection time. The constants of exponential equation obtained for different operating conditions can be used by the designers of pressurized irrigation system for economical and accurate use of pressure difference method of injecting fertilizers.