Determination of the water diffusivity of horticultural substrates: comparison of different approaches for the one-step outflow data analysis

  • Carlo Bibbiani | carlo.bibbiani@vet.unipi.it Department of Veterinary Science, University of Pisa, Italy.
  • Carlo A. Campiotti Department UTEE-AGR, ENEA, Roma, Italy.
  • Luca Incrocci Department of Agriculture, Food and Environment Science, University of Pisa, Italy.
  • Alberto Pardossi Department of Agriculture, Food and Environment Science, University of Pisa, Italy.

Abstract

The improved iterative method for the simultaneous determination of the hydraulic properties of growing media from one-step experiment by Bibbiani, was performed on pure peat, pure pumice, and peat/pumice (1peat:1pumice by volume) mix, and compared with simplified equations by Valiantzas and Londra, who set up a new two-point method for calculating the water diffusivity, and with Van Genuchten- Mualem model. Brooks and Corey equations for water retention and hydraulic conductivity characterized the hydraulic properties of the porous media in relation to the iterative procedure. In the present work, the estimated water retention curves are compared with nine experimental data, and with the estimation of the Van Genuchten- Mualem model, via the RETC code, taking into account retention and diffusivity data. Bibbiani’s and Van Genuchten-Mualem’s estimations overlap except for the very wet range near saturation (R2 equals to 0.9997, 0.9999, 0.9998 for pure pumice, 1peat:1pumice mix, and pure peat respectively, for Bibbiani’s estimation; R2 equals to 0.9923, 0.9541, 0.9993 for pure pumice, 1peat:1pumice mix, and pure peat respectively, for Van Genuchten-Mualem’s estimation), whereas the Valiantzas and Londra’s procedure didn’t get satisfactory results, apparently because of different requirements related to the final pressure head applied in one-step experiment. In regard to diffusivity, a good similarity between Bibbiani’s and Van Genuchten-Mualem’s curves can be assessed, being the mean ratio values of the D(θ) from Valiantzas equation divided by D(θ) from Bibbiani equation equal to 1.20, 1.10, and 1.31 for pure pumice, 1peat:1pumice mix, and pure peat respectively, while Valiantzas and Londra’s procedure generally results in higher values. Due to the lack of estimation of the water retention curve, Valiantzas and Londra’s procedure fails to estimate the hydraulic conductivity function, whereas Bibbiani’s and Van Genuchten-Mualem’s curves match together in most cases.

Downloads

Download data is not yet available.
Published
2014-02-28
Section
Original Articles
Keywords:
hydraulic characteristics of substrates, one-step experiment, parameter estimation.
Statistics
Abstract views: 1526

PDF: 329
HTML: 369
Share it

PlumX Metrics

PlumX Metrics provide insights into the ways people interact with individual pieces of research output (articles, conference proceedings, book chapters, and many more) in the online environment. Examples include, when research is mentioned in the news or is tweeted about. Collectively known as PlumX Metrics, these metrics are divided into five categories to help make sense of the huge amounts of data involved and to enable analysis by comparing like with like.

How to Cite
Bibbiani, C., Campiotti, C. A., Incrocci, L., & Pardossi, A. (2014). Determination of the water diffusivity of horticultural substrates: comparison of different approaches for the one-step outflow data analysis. Journal of Agricultural Engineering, 44(4), 160-165. https://doi.org/10.4081/jae.2013.219

Most read articles by the same author(s)