GUICS: A Generic User Interface for On-Farm Crop Simulations

bling the input data may be a formidable task. Developing a user interface that incorporates these tools has As knowledge of crop growth and development is quantified, it been recognized as an essential step toward increasing can be included in the computer code of crop simulators that mimic the essential features of plant–soil–atmosphere–management interacthe utility of crop simulators and decision support systions. The next step necessary is to provide tools to simplify operation tems (Landivar et al., 1989; Cox, 1996). of the crop simulator by end users. Our objectives were to (i) develop Command-line interfaces have been replaced during a graphical user interface (GUI) specifically oriented to on-farm use the last decade with graphical user interfaces (GUI) and (ii) research the possibility of building a generic GUI that could based on graphics (icons, pictures. and menus) instead be used with many crop simulators not necessarily having the same of text. User interface design and implementation is a structure of input data. We call the interface GUICS (standing for growing field in software engineering (Redmond-Pyle Graphical User Interface for Crop Simulations). GUICS is built on and Moore, 1995). The theoretical background of user the usability paradigm developed by software designers and has a interface development lies in human–computer interacuser-centered design based on results of human–computer interaction tion studies (Macaulay, 1995). The functioning of human studies. The usability of the interface is facilitated with special features that enhance the directness, user-in-control, consistency, forgiveness, cognition and memory has profound implications for feedback, and simplicity of the interface. Including a simulator in interface development (Mandel, 1997). GUI developGUICS is a straightforward operation that does not require changes ment is centered on setting the usability requirements in the simulator code. The GUICS prototype was evaluated by its (Redmond-Pyle and Moore, 1995) that will simplify the future users in interviews during which they had hands-on experience. performance of predefined tasks. The issues addressed Two years of on-farm use of GUICS has proved the usability of are ease of learning, elimination of sources of errors, the interface. ergonomics, and prevention of frustration and negative feelings about the interface. The main issue, however, is understanding the user’s needs. K dissemination and delivery to the end Several graphical user interfaces to crop models are users have always been important tasks in agrodescribed in the literature (e.g., Hoogenboom et al., nomic research. As knowledge of crop growth and de1994; Van Evert and Campbell, 1994; Waldman and velopment is quantified, it can be included in compuRickman, 1996; Testezlaf et al., 1996). All of them have ter code of crop simulators that mimic plant–soil– been built specifically for a single crop model or for a atmosphere–management interactions. The relatively family of models. In spite of several attempts to stanshort 30-year history of computer crop simulation has dardize crop simulators, the numbers and contents of seen the establishment of principles and techniques, as input and output files vary from one crop simulator to well as the development of several widely used crop another. This does not mean, however, that each crop simulators and crop simulator families, such as CERES, simulator or family (suite) of crop simulators must have EPIC, CROPGRO, CROPSYST, GOSSYM, and its own GUI. Learning several different GUIs to perGLYCIM. form similar tasks with different crop simulators is neiDeveloping a simulator is the most important but only ther a necessary nor a desirable use of time for such the first step in knowledge dissemination. The next step busy people as farmers. Therefore, there is a need to is to provide tools to simplify operation of the crop develop a generic GUI that can be used with all, or at simulator by end users. The need for such tools stems least most, crop simulators—a need that has already from limits to the computer literacy of users, and from been discussed (e.g., Rewerts et al., 1989; Wu, 1992). the lack of free time for learning and/or performing Crop simulators have various groups of users, includtedious procedures for entering data and displaying reing consultants, farmers, students, and researchers. The sults. Without these tools, potential benefits from the uses of crop simulators vary among the groups, and use of the simulators may not be realized, and assemso do the usability requirements. Farmers constitute potentially the largest group of crop simulation users. B. Acock and V.R. Reddy, Remote Sensing and Modeling Lab., On-farm crop simulations provide decision support inUSDA-ARS, Beltsville, MD 20705; Ya. Pachepsky, Duke Univ. Phyformation for farm operations. The on-farm simulations totron and USDA-ARS Remote Sensing Modeling Lab., Bldg. 007, Room 008, BARC-West, Beltsville, MD 20705; E. Mironenko, Dep. should provide (i) warnings of the need to perform of Horticulture, Univ. of Maryland at College Park, College Park, certain management operations and (ii) a summary of MD 20742; and F.D. Whisler, Dep. of Soil and Plant Sciences, Missisthe consequences of doing or not doing the operation. sippi State Univ., Mississippi State, MS 39762. Received 23 Sept. 1998. *Corresponding author ([email protected]). Abbreviations: DLL, dynamic link library; DSS, decision support system; GUI, graphical user interface. Published in Agron. J. 91:657–665 (1999).