Article:

Roth, O., Derron, J., Fischlin, A., Nemecek, T. & Ulrich, M., 1995. 
        Implementation and parameter adaptation of a potato crop simulation model 
        combined with a soil water subsystem. In: Kabat, P., Marshall, B., van den 
        Broek, B.J., Vos, J. & van Keulen, H. (eds.), Modelling and parametrization 
        of the soil-plant atmosphere system - a comparison of potato growth models. 
        Wageningen Pers, Wageningen, The Netherlands, pp. 371-399.

Abstract:

For the study of virus epidemics in Swiss seed potatoes a simple, yet useful crop growth model was needed. It had to provide information on tuber yield, leaf area, leaf age (for age resistance) and responses to water excess or deficit. The model of Johnson et al. (1986) satisfied most of these criteria. However this model does not compute the water stress factor from easily available weather data. Therefore we built a submodel for the soil water balance based on published models (Van Keulen & Wolf, 1986) and combined it with a new implementation of the Johnson model.

For this purpose the simulation environment ModelWorks with its open system architecture and numerous interactive features e.g. for parameter settings and graphing, proved to be most useful. The model's parameters were identified by graphical examination and automatic iterative minimization of the squared differences of the simulated and the given crop calibration data sets.

For most situations the simulated results showed satisfactory agreement with the measured data. The simulated qulitative and quantitative behavior fitted the observations similarly for the calibration and their equivalent validation data sets, both for potential and drought conditions. The exception is the leaf area index, which is usually due to the considerably simple model structure simulated with less accuracy than the tubers or other plant parts. The coupled soil water balance model contains more details and fits the validation data in most cases very well. For the purpose of our study we consider the overall model output to be satisfactory.

Full text (2.4MB)