The use of high permeability soils with low plant available water content (PAWC) for cultivation of plants in the greenhouses, green roofs, and urban green spaces requires frequent irrigation, which leads to high water consumption. This paper presents an innovative method consisting of combined use of sustainably produced liquid organic fertilizer (LOF) extracted from landscape grass waste and clinoptilolite zeolite for improving PAWC of sand. The study included four substrates, namely sand (S), sand with 20% zeolite (SZ), sand treated with LOF (SLOF), and sand with 20% zeolite treated with LOF (SZLOF), to evaluate the effect of LOF and zeolite on PAWC of sand. The effect of three growth medium treatments, sand that received LOF fertilizer (LOF1), sand with 20% zeolite that received LOF fertilizer (ZLOF), and sand that received inorganic fertilizer (CF1), through a greenhouse experiment during two growing seasons (fall and summer) on productivity of perennial ryegrass (Lolium perenne) and properties of its growth medium was also evaluated. Combined use of LOF and zeolite increased the volumetric water content of sand by 29, 154, and 220% at 0, 30, and 100 centibar (CB) suctions compared to S substrate, respectively, and increased the dry biomass yield (DBY) of perennial ryegrass by 42% in ZLOF during the summer season compared to CF1 growth medium. Additionally, the content of organic matter, nitrogen, and phosphorus increased by 25, 120, and 84%, respectively, for ZLOF treatment compared to 33, 40, and 53% for LOF1 treatment. The outcomes of the experiments demonstrate the feasibility of using LOF and zeolite to improve the PAWC of sand and DBY of perennial ryegrass.
