An agricultural water retention system including a subsurface water retention barrier positioned in soil below a root zone of one or more plants wherein the subsurface water retention barrier consists of a plurality of hydrophobic beads layered in a loosely packed manner and wherein the subsurface water retention barrier is air permeable. Optionally, there is also included a surface evaporation barrier positioned proximate a surface of the soil, such that the surface evaporation barrier includes at least one layer of hydrophobic beads.