An agricultural spreader has a hopper containing a granular material, a boom arm with a plurality of spreader nozzle assemblies configured to disperse the material and a pneumatic supply to propel the granular material from the hopper, and out the spreader nozzle assemblies. The spreader nozzle assemblies include a conduit defining a pathway through which the material is delivered and a spreader nozzle in fluid communication with the pathway. A piezoelectric material is located within the pathway. A light source is located proximate the spreader nozzle and in electrical communication with the piezoelectric material. The light source arranged to direct emitted light into a spread pattern produced by the spreader nozzle.
