Estimation of Water Retention Characteristics Depending on the Particle Sizes of Perlite Using van Genuchten Equation with Retention Curve Program

Abstract

The estimation of water retention for perlite particles, which are used as growth media need to set up for proper water management strategy due to uncertain available water proportion during growth period of vegetable crops in a greenhouse. The water retention curves (WRC) expressed as volumetric water content (θ v ) were constructed with five different sizes of the expanded perlite after fully saturating and packing the perlite in open-ended metal cubes at 11 levels of matric potentials from 0 to -1,500 kPa. The best fitted four parameter values (θ s , θ r , n, α) of the van Genuchten model (vG model) for the substrate samples were obtained using the Retention Curve Program (RETC) based on the values measured water content at the corresponding matric potentials. The particle size corresponding to 36.8 percentage by mass of particles was 0.80065 mm. The calculated uniformity coefficient and the coefficient of gradation for the perlite were 1.962 and 2.51 mm, respectively. Measured water contents at each matric potential increased with decreasing particle size of perlite while the difference of water content between saturation (θ s ) and residual state (θ r ) increased with increasing particle size. The mean R 2 for all sizes of the perlite particle was suitable to predict θ v because the measured data points did not vary around the estimated regression line. Therefore, PTF performance based on van Genuchten (vG) equation using data set including perlite particle size can be applicable to estimate water retention in perlite particles.

The impact of compost and expanded perlite on soil physical properties and water productivity under different irrigation practices

“…In addition, perlite has a very high air capacity with a mean value of 60.2%. Hence, expended perlite has an appropriate retention capacity of water and air whose application can act as a betterment for the increase of soil water capacity (Markoska et al, 2018a;Lim et al, 2021). Thus, perlite…”