An improvement to the iterative method for the simultaneous determination of soil hydraulic properties from One-Step data proposed by Valiantzas and Kerkides (1990) was developed. Inserting in the optimization algorithm one more parameter, residual water content 'r', completed the revised equation. Soil hydraulic properties were characterized by the Brooks and Corey equation for water retention, and by the Kozeny power equation for hydraulic conductivity. The iterative procedure was tested using a particular class of soilless substrates generally used in container cultivation represented by three different mixes comprised of peat and pumice. The One-Step method was optimized and then tested on five replications of each mix. Analyzing the mean cumulative outflow curve recorded versus time, an estimation of hydraulic functions was derived. Estimated water retention was compared with nine experimental data and with the estimation by the Van Genuchten model. Keeping the same saturated water content 's', the two models overlap except for the “wet” range near saturation. Estimated hydraulic conductivity was compared with the estimation derived from the Van Genuchten-Mualem equation. The comparison showed a very high similarity between the two curves.
An iterative procedure to estimate hydraulic characteristic of plant substrates from one-step outflow data
BIBBIANI, CARLO
2002-01-01
Abstract
An improvement to the iterative method for the simultaneous determination of soil hydraulic properties from One-Step data proposed by Valiantzas and Kerkides (1990) was developed. Inserting in the optimization algorithm one more parameter, residual water content 'r', completed the revised equation. Soil hydraulic properties were characterized by the Brooks and Corey equation for water retention, and by the Kozeny power equation for hydraulic conductivity. The iterative procedure was tested using a particular class of soilless substrates generally used in container cultivation represented by three different mixes comprised of peat and pumice. The One-Step method was optimized and then tested on five replications of each mix. Analyzing the mean cumulative outflow curve recorded versus time, an estimation of hydraulic functions was derived. Estimated water retention was compared with nine experimental data and with the estimation by the Van Genuchten model. Keeping the same saturated water content 's', the two models overlap except for the “wet” range near saturation. Estimated hydraulic conductivity was compared with the estimation derived from the Van Genuchten-Mualem equation. The comparison showed a very high similarity between the two curves.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
