Modeling biomass growth, N-uptake and phenological development of potato crop
Introduction
One of the main topics in agronomic research is to find management strategies that maximize crop production and minimize environmental degradation. An appropriate complement to experimental data is the utilization of simulation models, which can provide an efficient interpretation of data, and also analyze the behavior of agricultural systems under diverse environmental conditions. Investigations using models are faster and more economical than experimental studies alone, and models represent helpful tools through which decision-making processes in sustainable agricultural systems occur. However, in order for simulation models to be useful instruments in agricultural practice, comparison to field experimental data is essential.
A powerful tool for simulating daily fluxes of water, carbon and nitrogen in agroecosystems is the modeling system Expert-N Engel and Priesack, 1993, Baldioli et al., 1995, Stenger et al., 1999. It consists of several modules for simulating different processes in the soil–plant–atmosphere system, which can be coupled together in various combinations. Defined interfaces exist between the single-process modules, which must be kept if new modules are integrated in the modeling system.
During the last years, Expert-N was successfully used to simulate water transport and nitrogen turnover processes within the scope of the FAM Research Network on Agroecosystems. Water transport modules were adapted to the special conditions at the sampling locations within the Research Station Scheyern (Priesack et al., 1999), and many experiments were carried out to provide the data required by Expert-N (Scheinost et al., 1997). To consider crop growth in an explicit way and to thus extent the performance of Expert-N, now the process-oriented model for the description of growth and uptake processes of field crops, Soil Plant Atmosphere System Simulation (SPASS), was integrated in the modeling system. Implementation of SPASS was carried out subject to the modular structure of Expert-N system, to allow the combination of SPASS with the soil modules already available in Expert-N. SPASS is intended to be a generic model for simulating crop growth. A simulation model may termed “generic”, if it simulates several functionally and structurally equivalent systems solely through the use of different parameter values. This approach encourages modelers to determine general properties of the class of systems (similarities) and to view individual systems as variations, rather than as separate entities (Reynolds et al., 1989). In case of crop models, a generic model structure can be established by recognizing the general process common to all crops and this overall model structure may be then applied to all crop types. Functionally equivalent crop species can be simulated solely by model re-parameterization using species-specific parameters. Although divergences in physiological and ecological principles between crop classes (e.g. cereals and root crops) may require modifications of single process formulations, the overall model structure should remain unchanged. Thus, the integration of one generic crop model into the Expert-N modeling system provides a more efficient way to simulate several crop species rather than the integration of numerous single species models.
SPASS has been thoroughly tested for winter wheat by Wang (1997) before its integration into Expert-N. The goal of the present study was to modify the SPASS model to simulate potato crops by investigating the changes in process formulations required for this modifications and, further, to test the reliability of model predictions. Therefore, SPASS was calibrated using data from a potato crop fertilization experiment carried out within the FAM program. In order to test the reliability of model predictions, simulated tuber yields and nitrogen uptake were compared with experimental results obtained in different years at other fields at the Research Station Scheyern.
All simulations reported in this paper were carried out by combining the crop model SPASS with soil modules according to the LEACHN model (Hutson and Wagenet, 1991), also implemented in the Expert-N modeling system. LEACHN is based on the Richards-Equation and describes the one-dimensional, vertical water and nitrogen transport in the unsaturated soil zone, as well as nitrogen transformation processes.
Section snippets
Experimental data
In order to parameterize the SPASS model and test its suitability to simulate potato growth, we used experimental data from a detailed study carried out in the 1996 vegetation period (April to October) at seven investigation plots in Scheyern (description of the Research Station Scheyern, see Schröder et al., 2001, same issue). The investigation plots were 30 m2 in size. Two varieties of potato, “Christa” and “Agria”, representing early and late maturity classes, respectively (ZADI, 1999), were
Model calibration
Whereas most of the parameter values required for model parameterization were taken from Penning de Vries et al. (1989), Ritchie et al. (1987) and Jones et al. (1986), those values required for simulating phenological development, assimilate partitioning and nitrogen uptake had to be estimated. Model calibration was done on the basis of data measurements from a fertilization study as previously described. Parameter values required for simulating phenological development were deduced from
Discussion and conclusions
In the present study, the crop model SPASS was adapted to simulate potato-growth processes. To accomplish this, a novel parameterization with potato-specific parameters and minor modifications of some process formulations were required, as compared to the wheat version of the SPASS-model. The following modifications were carried out: (i) in the submodel for the simulation of phenological development, an additional variable, the tuberization rate, was introduced; (ii) the pool of assimilates
Acknowledgements
Thanks are due to the German Federal Ministry for Education and Research (BMBF 0339370) and the Bavarian State Ministry for Science, Research and the Arts for the financial support of the FAM Research Network on Agroecosystems, and the German Research Foundation (DFG), who supports the program SFB 607 “Wachstum oder Parasitenabwehr”.
References (26)
- et al.
Statistical validation
Ecological Modelling
(1993) - et al.
Regionalisation of soil water retention curves in a highly variable soilscape: I. Developing a new pedotransfer function
Geoderma
(1997) - Baldioli, M., Engel, T., Priesack, E., Schaaf, T., Sperr, C., Wang, E., 1995. Expert-N, ein Baukasten zur Simulation...
- et al.
Expert-N, a building-block system of nitrogen models as resource for advice, research, water management and policy
- FAM Database,...
- et al.
Modelling potential crop growth processes
Textbook with Exercises
(1994) - Griffin, T.S., Johnson, B.S., Ritchie, J.T., 1993. A simulation model of potato growth and development: SUBSTOR-Potato...
- Groot, J.J.R., 1987. Simulation of nitrogen balance in a system of winter wheat and soil. Simulation report CABO-TT nr....
- et al.
The dilemma of plants: to grow or to defend
Quarterly Review of Biology
(1992) - et al.
A modular structure for crop simulation models: implementation in the SIMPOTATO model
Agronomy Journal
(1992)
Simulating nitrogen dynamics in soils using a deterministic model
Soil Use and Management
Subroutine structure
Modelling development and growth of the potato crop influenced by temperature and daylength: LINTUL-POTATO
Cited by (65)
Assessing the impact on crop modelling of multi- and uni-variate climate model bias adjustments
2024, Agricultural SystemsBayesian multi-level calibration of a process-based maize phenology model
2022, Ecological ModellingIntegrated phenology and climate in rice yields prediction using machine learning methods
2021, Ecological IndicatorsPerformance of the SUBSTOR-potato model across contrasting growing conditions
2017, Field Crops ResearchCitation Excerpt :Previous studies also tested various potato cultivars but were often limited in the number of cultivars. Other studies had analyzed model performance for a single cultivar with the models SIMPOTATO and DANUBIA (Hodges et al., 1992; Gayler et al., 2002; Lenz-Wiedemann et al., 2010); six cultivars with the model SUBSTOR-potato (Griffin et al., 1993); seven cultivars with the model DAISY (Heidmann et al., 2008); and 10 cultivars with the model INFOCROP (Aggarwal et al., 2006). Only one model, SOLANUM, was used to compare simulated and observed yields for a large number of potato species (Condori et al., 2010).
Improving potato drought simulations: Assessing water stress factors using a coupled model
2015, Agricultural and Forest MeteorologyImproving the estimation and partitioning of plant nitrogen in the RiceGrow model
2018, Journal of Agricultural Science