Faba bean (Vicia faba L.) is a very productive N-fixing legume that originated in Mediterranean regions where it is commonly grown during winter-spring season.  Its seed is widely used for human consumption as a vegetable and often in soups/dal and paste in sandwiches, but it is also used for animal feed.  There are fall-sown ecotypes for the Mediterranean region, North Africa, India, as well as spring-sown ecotypes that are grown further north in Europe.  It is considered drought tolerant because of its flexible phenology pattern.

The CROPGRO-Fababean model was developed by Boote et al. (2002), patterned after the CROPGRO-Soybean model (Boote et. al., 1998) and adapted based on excellent growth analysis for two faba bean cultivars (Alameda and Brocal) grown under N-fixing and N-fertilized treatments under irrigated conditions in two seasons in Cordoba, Spain (Sau and Mınguez, 2000).  Boote et al. (2002) followed a sequential approach for adapting the species, ecotype, and cultivar traits based on:  1) literature information on temperature sensitivity of processes and tissue compositions, and 2) manually optimizing parameters affecting phenology, onset of reproductive growth, leaf area expansion, dry matter partitioning, tissue N concentrations, and photosynthetic productivity based on time-series observations of crop growth.   

The model requires inputs of management practices, environmental conditions and cultivar-specific traits (genetic coefficients) to predict daily growth and development (Boote et al., 1998). The species file describes characteristics assumed constant across cultivars such as tissue composition, partitioning, and sensitivity of processes to temperature, light, plant water deficit, and plant N deficiency. The required ecotype and cultivar data include lengths of developmental phases, vegetative traits, leaf traits, reference seed size, and seed composition (Jones et al., 2003). As with the other CSM-CROPGRO models (Boote et. al., 1998; Jones et al., 2003), the faba bean model shares the same source code including a hedge-row light interception model (Boote and Pickering, 1994) combined with a leaf-scale photosynthesis model based on the Farquhar approach for simulating response to CO₂.  

Differences from soybean include:  1) being a cool-season crop with lower cardinal temperatures (see Boote et al., 2002) that allow it to grow over mild winters and being tolerant of moderate frost/freezing conditions, 2) being a long-day species parameterized with a Critical Long Daylength (CLDL) of 24 hr and PPSEN value of -0.031, negative being used for long-day species, 3) having a low oil content, 4) actually being more productive with higher N-fixation capacity than soybean.  However, the crop is not tolerant to high humidity conditions.  

The CSM-CROPGRO-Faba bean model was used by Sau et al. (2004) and by Boote et al. (2009) to evaluate the crop and soil water balance and ET based on the Sau and Minguez (2000) experiments.  Confalone et al. (2011) explored the effects of photoperiod and temperature parameterization of reproductive phenology and rate of leaf appearance of faba bean cv. Alameda based on multiple sowing dates over the season in Lugo, Spain. However, these improved parameters are not yet in the current version of the faba bean model).  The CSM-CROPGRO-Faba bean model is relatively new, and would benefit from evaluation in other regions. In addition to Spain, the model also was evaluated for conditions in Egypt (Hassanein et al., 2007). Also, the improved temperature and daylength parameterization of Confalone et al. (2011) needs to be incorporated into the current version of CSM (Jones et al., 2003; Hoogenboom et al., 2019), and the model should be evaluated against drought conditions that cause up to 10-day acceleration of onset of reproductive growth. 

References

• Boote, K. J., J. W. Jones, G. Hoogenboom, and N. B. Pickering.  1998.  The CROPGRO model for grain legumes.  pp. 99-128.  In: G. Y. Tsuji, G. Hoogenboom, and P. K. Thornton (eds.) Understanding Options for Agricultural Production.  Kluwer Academic Publishers, Dordrecht. 
• Boote, K. J., M.I. Mínguez, and F. Sau.  2002.  Adapting the CROPGRO legume model to simulate growth of faba bean.  Agronomy Journal 94:743-756.
• Boote, K.J., and N.B. Pickering. 1994. Modeling photosynthesis of row crop canopies. HortScience 29:1423–34. 
• Boote, K. J., F. Sau, G. Hoogenboom, and J. W. Jones.  2009.  Experience with water balance, evapotranspiration, and prediction of water stress effects in the CROPGRO Model.  In:  L. R. Ahuja, V. R. Reddy, S. A. Saseendran, and Q. Yu (Eds.) Response of Crops to Limited Water:  Modeling Water Stress Effects on Plant Growth Processes, Volume 1 of Advances in Agricultural Systems Modeling.  ASA-CSSA-SSSA, Madison, WI. 
• Confalone, A. K. J. Boote, J. I. Lizaso, and F. Sau.  2011.  Temperature and photoperiod effects on Vicia faba phenology simulated by CROPGRO-Fababean.  Agronomy Journal 103:1036-1050. 
• Hassanein, M.K., M.A. Medany, M.E. Haggag, and S.S. Bayome. 2007. Prediction of yield and growth of faba bean using CROPGRO legume model under Egyptian conditions. Acta Horticulturae 729: 215-219. DOI: 10.17660/ActaHortic.2007.729.34.
• Hoogenboom, G., C.H. Porter, K.J. Boote, V. Shelia, P.W. Wilkens, U. Singh, J.W. White, S. Asseng, J.I. Lizaso, L.P. Moreno, W. Pavan, R. Ogoshi, L.A. Hunt, G.Y. Tsuji, and J.W. Jones. 2019. The DSSAT crop modeling ecosystem. In: p.173-216 [K.J. Boote, editor] Advances in Crop Modeling for a Sustainable Agriculture. Burleigh Dodds Science Publishing, Cambridge, United Kingdom (http://dx.doi.org/10.19103/AS.2019.0061.10).
• Jones, J.W., G. Hoogenboom, C.H. Porter, K.J. Boote, W.D. Batchelor, L.A. Hunt, P.W. Wilkens, U. Singh, A.J. Gijsman, and J.T. Ritchie. 2003. The DSSAT Cropping System Model. European Journal of Agronomy 18:235–65.
• Sau, F., K. J. Boote, W.M. Bostick, J.W. Jones, and M.I. Minguez. 2004. Testing and improving evapotranspiration and soil water balance of the DSSAT crop models. Agronomy Journal 96:1243-1257.
• Sau, F., and M.I. Mınguez. 2000. Adaptation of indeterminate faba beans to weather and management under a Mediterranean climate.  Field Crops Research 66:81–99.