Abstract: An irrigation system comprises a water supply, a plurality of irrigation heads in fluid connection with the water supply, and a fertilizer assembly between the water supply and a first irrigation head, the fertilizer assembly in fluid connection with the water supply and the first irrigation head, the fertilizer assembly comprising a fertilizer valve connected to a fertilizer container. Water is provided from the water supply to the fertilizer assembly, where it is mixed with fertilizer provided via gravity from the fertilizer container in the mixing chamber to form fertilized water. The fertilized water is then provided to at least one of the irrigation heads of the system.