The present invention provides a mixture comprising: a) a first composition comprising a culture of microalgae; and b) a second composition comprising a fertilizer; wherein a combination of the first composition and the second composition exhibits synergy. Also provided is a method of treating a plant, a plant part, or the locus surrounding the plant to enhance plant growth and/or yield, the method comprising applying an effective amount of the disclosed mixture to the plant, plant part, or the locus surrounding the plant.