An apparatus including an air blower; a rotary airlock; a receptacle having an inner chamber supplied with a plurality of colorant particles; a water supply; and a mixing chamber. The air blower blows air into a bottom section of the rotary airlock, and the rotary airlock receives colorant particles from an output of the receptacle. A rotor shaft of the rotary airlock rotates to cause colorant particles to be transported to the bottom section of the rotary airlock. Air blown into the bottom section of the rotary airlock mixes with colorant particles transported into the bottom section of the rotary airlock to form an air and colorant particles mixture, which is blown out of a first output of the rotary airlock and combined with water to form a water, air, and colorant particles mixture, which is mixed with material in a mixing chamber. The material may be natural mulch.