The present invention relates to a mobile sand injector for injecting sand into the ground, the device comprising: - a base frame configured to be moved over a pitch, - a liquid supply connector for connection to a source of pressurized liquid, - at least one storage compartment for sand, - a plurality of mixing chambers for mixing the sand with the liquid, - a plurality of injector nozzles for injecting the mixture of sand and liquid into soil under the pitch, wherein each injector nozzle is associated with a mixing chamber, - a plurality of liquid supply conduits, wherein each mixing chamber is connected to at least one liquid supply conduit, wherein the liquid supply conduit supplies pressurized liquid from the source of pressurized liquid to the mixing chamber, - a plurality of sand supply tubes, wherein each mixing chamber is connected to at least one sand supply tube, wherein the sand supply tubes are configured for supplying sand to the respective mixing chambers,- a control system and at least one operable valve configured for providing a volume of pressurized liquid in pulse form through the liquid supply conduits and into each mixing chamber, wherein the volume of liquid mixes with a quantity of sand in each mixing chamber and wherein the mixture is ejected into the ground, wherein the device comprises a vibration device configured to vibrate the sand supply tubes in order to feed the sand through the sand supply tubes into the mixing chambers.
