PTF: an Extensible Component for Sharing and Using Knowledge on Pedo-transfer Functions

Abstract

A high number of procedures to estimate soil hydrological parameters has been developed, using different methods based on regression, either physically based or physical-empirical approaches or neural networks . It can be very difficult for a user to select what is the more appropriate method for a specific application. Some already existing software, e.g Soilpar2 [Acutis and Donatelli, 2003] present a collection of pedo-transfer functions (PTF), with some possibility to store and visualize soil data, compare estimation against measured data, and evaluate the performance of different PTF. Main limits of SoilPar2 and similar software is that they are close applications, hence it is not possible to add other PTFs not included in the application. Also, there is no quality control on data used. Finally, such applications cannot be used as servers in custom developed applications. A software component with the following main requirements is presented in this paper: i) easy to reuse; ii) with a clear ontology of the variables used in each PTF, where units, value range, and significance are unambiguously defined; iii) extensible by third parties independently, allowing for an open system to which scientists can contribute; iv) freely available for non-commercial use. The PTF component was developed following the design by Donatelli and Rizzoli [2007] to match the requirements above and others. The components implements the ¿Design by contract¿ through a dependency to an external component called ¿Precondition¿ (http://www.apesimulator.it/help/utilities/preconditions), available both for the .NET and Java frameworks. The component is developed in .NET using C#, but a Java version is also available. The software development kit (SDK) of the component PTF includes simple console clients in C#, VB.Net, and Java, and examples of extension of the component both for the domain class (the model data-type) and for pedo-transfer function, coded using VB.Net and C#. The SDK includes also the code of projects of a web service and of a web application, code documentation, and an extensive help.