That, as awesome as it sounds, would be super massive overkill. It would be on the order of using ICBM equipped with multiple nuclear warheads to rid your dog of fleas.
Just a small chunk of neutronium moving even at somewhat conventional speeds would be more then enough kinetic energy to devastate the planet.
The weapon described would be something I would use to destroy Dyson Sphere type objects, that is, technology of type II civilization(one that is harnessing nearly all the energy of a star by building a sphere around it to capture the majority of the radiation to convert it into usable energy of some form).