Impact model: PRYSBI2

The characteristics of this model is that, in this model, certain model parameters were estimated using Bayesian statistics with a Markov-Chain Monte Carlo (MCMC) method based on field observation data. This process allows for the model parameters to be calibrated to fit any region or scale. The model repeatedly performs hundreds of thousands of calculation steps in the MCMC process. Therefore, although the model must be sufficiently complex to describe the response of soybean production to increased atmospheric CO2, it should be relatively simple and include the fewest parameters possible to shorten the calculation time for each MCMC step. The model incorporates the big-leaf model and has a simple structure. The dynamics of mineral nutrients, such as nitrogen, are not considered. The daily partitioning of the photosynthate to each organ is estimated allometrically: the ratio of leaf biomass to total biomass is related to the degree of development of the crop, which is determined only by cumulative temperature. To calculate photosynthetic carbon assimilation, we used the enzyme kinetics model developed by Farquhar et al. (1980). To calculate soil water balance, we used a two-layer sub-model of the Soil & Water Assessment Tool (SWAT) model (Neitsch et al. 2005) but did not include lateral transport. PRYSBI2 is one of the 14 models following the ISIMIP2a protocol which form the base of simulations for the ISIMIP2a agricultural sector outputs; for a full technical description of the ISIMIP2a Simulation Data from Agricultural Sector, see this DOI link: http://doi.org/10.5880/PIK.2017.006

Sector
Agriculture
Region
global
Contact Person
  • Gen Sakurai (sakuraigen@affrc.go.jp), National Agriculture and Food Research Organization (NARO), Institute for Agro-Environmental Sciences (NIAES) (Japan)

Information for the model PRYSBI2 is provided for the simulation rounds shown in the tabs below. Click on the appropriate tab to get the information for the simulation round you are interested in.

Basic information
Model Version: Version2.2
Reference Paper: Main Reference: Sakurai G, Iizumi T, Nishimori M, Yokozawa M et al. How much has the increase in atmospheric CO2 directly affected past soybean production?. Scientific Reports,4,,2014
Reference Paper: Other References:
Output Data
Experiments: historical
Climate Drivers: WATCH (WFD), WATCH+WFDEI
Date: 2016-02-11
Resolution
Spatial Aggregation: regular grid
Spatial Resolution: 0.5°x0.5°
Additional Spatial Aggregation & Resolution Information: The original spatial resolution of PRYSBI2 is 1.125˚x1.125˚. Therefore, the output of the model was interpolated to 0.5˚x0.5˚ grids.
Temporal Resolution Of Input Data: Climate Variables: daily
Temporal Resolution Of Input Data: Co2: annual
Temporal Resolution Of Input Data: Soil: constant
Input data sets used
Observed Atmospheric Climate Data Sets Used: WATCH (WFD), WATCH+WFDEI
Climate Variables: tasmax, tas, tasmin, wind, rhs, rsds, pr
Additional Input Data Sets: Planting date (Sacks et al. 2010) Sacks, J. W., Deryng, D., Foley, J. A. & Ramankutty, N. Crop planting dates: an analysis of global patterns. Glob. Ecol. Biogeogr. 19, 607–620 (2010).
Spin-up
Was A Spin-Up Performed?: No
Key input and Management
Crops: Maize, Rice, Soybean, Wheat
Land Cover: Not considered
Planting Date Decision: Planting date is fixed at the planting date of Sacks et al. 2010.
Planting Density: Constant
Crop Cultivars: No
Fertilizer Application: No
Irrigation: No
Crop Residue: Not Aplicable
Initial Soil Water: 80% of field capacity
Initial Soil Nitrate And Ammonia: Nitrogen dynamics in the soil is not considered
Initial Soil C And Om: Carbon dynamics in the soil is not considered
Initial Crop Residue: Not Aplicable
Key model processes
Leaf Area Development: The leaf area is estimated from leaf biomass. The leaf biomass is estimated from aboveground biomass. The ratio of leaf biomass to aboveground biomass is linearly correlated with the growing stage. The relationship was assumed to be stable among years, varieties, and treatments.
Light Interception: Big leaf model
Light Utilization: To calculate photosynthetic carbon assimilation, we used the enzyme kinetics model developed by Farquhar et al. (1980). Farquhar, G. D., von Caemmerer, S. & Berry, J. A. A biochemical model of photosynthetic CO2 assimilation in leaves of c3 species. Planta 149, 78–90 (1980).
Yield Formation: Crop yields are calculated by simply multiplying harvest index (constant value from 0 to 1).
Crop Phenology: The period from emergence to maturity is determined by the total number of heat units.
Root Distribution Over Depth: We used the same ratio of root biomass to total biomass that is assumed in the SWAT model (Neitsch et al. 2004). The ratio varies from 0.40 at emergence to 0.20 at maturity. Neitsch, S. L., Arnold, J. G., Kiniry, J. R., Williams, J. R. & King, K. W. Soil and water assessment tool theoretical documentation (version 2005). (United States Department of Agriculture, 2005).
Stresses Involved: Temperature stress and Water stress
Type Of Water Stress: Photosynthesis rate is decreased according to water stress that is calculated by SWAT model (Neitsch et al. 2004). Neitsch, S. L., Arnold, J. G., Kiniry, J. R., Williams, J. R. & King, K. W. Soil and water assessment tool theoretical documentation (version 2005). (United States Department of Agriculture, 2005).
Type Of Heat Stress: 1. Photosynthesis rate is changed according to average temperature of the day. 2. Growing period is changed according to temperature, hence the degree of light absorption is changed.
Water Dynamics: Calculated by SWAT model (Neitsch et al. 2004). Neitsch, S. L., Arnold, J. G., Kiniry, J. R., Williams, J. R. & King, K. W. Soil and water assessment tool theoretical documentation (version 2005). (United States Department of Agriculture, 2005).
Evapo-Transpiration: Calculated by SWAT model (Neitsch et al. 2004). Neitsch, S. L., Arnold, J. G., Kiniry, J. R., Williams, J. R. & King, K. W. Soil and water assessment tool theoretical documentation (version 2005). (United States Department of Agriculture, 2005).
Soil Cn Modeling: Not considered.
Co2 Effects: Calculated by Farquhar model.
Methods for model calibration and validation
Parameters, Number And Description: The parameters relevant to total number of heat units needed for maturity, Irrigation capacity, technological parameter were estimated by MCMC for each 1.125˚ grid.
Calibrated Values: Different among grids.
Spatial Scale Of Calibration/Validation: 1.125˚x1.125˚
Temporal Scale Of Calibration/Validation: From 1982 to 2006.