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30
Jun
Fertilization is the process of adding fertilizer to irrigation water. Typically 28% nitrogen is injected into irrigation water to replace or supplement nitrogen fertilization. Fertilization allows nitrogen to be applied closest to plant uptake without additional field traffic.
The equipment required for irrigating and fertilizing is fairly simple and readily available from most irrigation dealers. A chemical backflow valve protects the water supply from contamination, and an anti-backflow injection valve prevents the system from letting irrigation water into the fertilizer supply tank when the injection pump is stopped.
A positive displacement jet pump pushes a calibrated rate of fertilizer into the irrigation water flow through a jet valve. The size of the jet pump needs to be adjusted according to the system and application. Pumps capable of injecting 1-100 gallons/hour are common for N applications, but micropumps capable of 1-100 ounces/hour can be used to neutralize micronutrients or acids in irrigation water.
The uniformity of nitrogen application depends on the uniformity of the irrigation system. If most of the nitrogen requirement is applied by irrigation, the uniformity of the irrigation system needs to be 90% or more. If the uniformity of the irrigation system is less than 90% or unknown, the N applied through the irrigation system needs to be a smaller fraction of the N requirement. Make sure all system repairs are done before fertilizing, the end guns and bend arms won't start or shut down when they are notorious for messing with fertilizing.
For fertilization to be part of a nitrogen management plan, it also needs to be backed up by irrigation. Self-propelled tall crop applicators and urea aerial applicators are a few options available to irrigators that prevent fertilizing in persistently wet weather.
