Estimating crop model parameters for simulating soybean production in Iran conditions

Abstract

Crop modelling has the potential to contribute to food security. In this study, to provide a simple model for estimating the soybean potential yield and phenological stages in Iran, a simulation model (SSM_iCrop2) was parameterized and tested. This model estimates the soybean phenological stages and potential yield based on the weather data (minimum and maximum temperature, solar radiation and rainfall) using the phenological models such as leaf area development, mass production and partitioning and soil water balance. Regarding the model parametrization, the two maturities groups of 3 and 5 with the temperature unit of 2000 and 2400 growth degrees day (GDD) were chosen. The model evaluation results indicated that the soybean yield ranged between 1.9 and 4.8 with the average of 3.5 t.ha−1, while the range of simulated yield changes between 1.8 and 4.7 with the average of 3.7 t.ha−1. Comparing the observed yield to the simulated yield, values of r, CV and RMSE were obtained 0.84, 13%, 0.5 t.ha−1 which indicates the high accuracy of the model. All of these results indicated that the estimated model parameters are high accuracy for use in the simulation of soybean yield at the country level.

Comprehensive yield gap analysis and optimizing agronomy practices of soybean in Iran

“…Yp simulation illustrated that Yp for the main soybean regions of Iran ranged between 4232 and 5086 kg/ha. The range of simulated yields agrees with the 4430-4860 kg/ha yield-potential range estimates discussed by Nehbandani et al (2020b), using the same model for Golestan Province, Iran.…”

“…The range of simulated yields agrees with the 4430–4860 kg/ha yield-potential range estimates discussed by Nehbandani et al . (2020 b ), using the same model for Golestan Province, Iran.…”

“…Nehbandani et al . (2020b) parameterized and evaluated the SSM-iCrop2 model for soybean cultivars in Iran (values of r , CV and RMSE were obtained at 0.84, 13% and 500 kg/ha, respectively). Therefore, we used their information in the current study.…”

“…The crop parameters were used in the model extracted from common cultivars of the regions including Katoul, Tellar, JK (Maturity group V, growth period of about 150 days) and Williams (Maturity group III, growth period of about 120 days). Nehbandani et al (2020b) parameterized and evaluated the SSM-iCrop2 model for soybean cultivars in Iran (values of r, CV and RMSE were obtained at 0.84, 13% and 500 kg/ha, respectively). Therefore, we used their information in the current study.…”

“…There is no agreed protocol for the application of BLA, and in some studies, an arbitrary boundary line is fitted to the data (Makowski et al, 2007). However, three general steps can be considered to obtain the boundary line (Shatar and McBratney, 2004;Makowski et al, 2007;Patrignani et al, 2014;Hajjarpoor et al, 2018):…”