A CERES Model Based Decision Support System For Nitrogen-Fertilization

CMDSSN was a kind of application system of computer software which was used to assistant people decision-making for nitrogen fertilization. That was build basing on subprogram of nitrogen element balance of CERES model and by means of Object-oriented programming. CMDSSN could simulate circulation process of soil organic matter and crop leftover as well as simulate hydrolyzation of carbamide and NO₃^- — N and could alse simulate nitrogen losing. CMDSSN might assist decision-making of nitrogen fertilization, appraise fertilization scheme and show dynamical change trend of NO₃^- —N and NH₄⁺—N of soil in practical production.According to the need for studying the problem, CMDSSN has been designed as a DSS(Decision Support System)of two databases, which was composed of a database system, model base system and a man-machine dialogue system.Model base system was the most important part of CMDSSN, which adopted nitrogen model of CERES. Model base system included four submodel which were respectively organic matter mineralization model, nitrification-denitrification model, nitrogenous leaching and fertilizer transform model. System adopt a form of function encapsulation which could enclose submodel in the course of programme and transfer directly by parameter, so it simplified programme code greatly as well as transferred expediently by other programme.There were weather database, fertilization information database, running result database, parameter database in the Database System of CMDSSN. The user could establish, browse, add, modify and delete data in the database easily realizing the database management, and for the experienced user, they could manage the data through Microsoft Access.CMDSSN was a application software, which offered beautiful interface of menu operation, it is easy for users to run model and manage database. Visual Basic6.0 was a tool and Windows operating system was a flat for CMDSSN. Plug-in package in Visual Basic ctGrid, Data Dynamics and ActiveBar made program more specialty. Users can choose a fashion of output, tables or curves, A table could contain a lot of data, while a curve would show direct information.