Reusing perlite substrates in soilless cultivation: analysis of particle size, hydraulic properties, and solarization effects

Using perlite substrates over several growing seasons is widely done in greenhouse production; its successful application depends on substrate modification and growing practices. The goal of this research was to characterize the evolution of the physical, hydraulic, and aeration properties of perlite with time within two parts of the pot, where the effect of solarization was also determined. New perlite and perlite that had been used one to four times as growing media were analyzed, and the induced modifications were measured in terms of the hydraulic retention, permeability at saturation, porosity, bulk density, water-holding capacity, and particle size distribution. The study showed that reuse influences the perlite particle size and reduces the hydraulic conductivity of the medium; the aeration properties and easily available water were improved by reuse, which supports crop growth. However, the variations found in this study from the reused substrates' hydraulic features would not significantly modify the irrigation regime of the growing media inside a greenhouse. The solarization did not substantially alter the primary physical and hydraulic properties of the medium. © 2015 American Society of Civil Engineers.