Navigation: Exploration mode

Exercise objective:

• Navigating the FSEWin Shell (selecting data files; running the model; viewing output).

• Contents of the experimental data file: EXPLORATION mode.

Suggested reading:

Chapters 7.1 and 7.2 of the book, ORYZA2000: modelling lowland rice.

This first set of exercises shows how to use ORYZA2000 to predict rice growth and development under conditions of potential production. In first instance, we do not simulate a particular experiment but use the model to make explorations for a given environment. In this case, we want to predict the potential yield of rice variety IR72, in the dry season of 1992, at the IRRI farm in Los Baños, the Philippines.

Exercise:

Ex-I.1. Start up the Shell FSEWinRunOnly from your desktop. Pull down the File Menu and Open Project ORYZAWin.fpf in  

C:\COURSE\NAVIGATE\.

On the left of the screen appears a directory structure with different types of files:

·      Input Datafiles: all input data files that are read by ORYZA2000

·      Output Datafiles: output data files that are produced by ORYZA2000.

·      Charts: a chart file in which outputs produced by ORYZA2000 can be viewed graphically.

Ex-I.2. Click with your mouse on CONTROL.DAT of the Input Datafiles. We see the content of the file displayed in the right hand box of the screen. Read Chapter 7.1 of the book ORYZA2000: modelling lowland rice for a detailed explanation of CONTROL.DAT. (Note: if the experimental data file is not EXPLORE.DAT, please change it into EXPLORE.DAT)

CONTROL.DAT lists all the data files that are used in this particular run of ORYZA2000. In this example, we focus on the following information:

FILEON = 'RES.DAT'                          ! Output file

FILEOL = 'MODEL.LOG'                        ! Log file

FILEIT = 'C:\COURSE\NAVIGATE\EXPLORE.DAT'   ! Experimental data

FILEI1 = 'C:\COURSE\NAVIGATE\IR72.D92'      ! Crop data

FILEIR = 'C:\COURSE\NAVIGATE\RERUNS.DAT'    ! Rerun file

*   FILEI2 = 'C:\COURSE\NAVIGATE\PADDY.DAT'    ! Soil data

The file RES.DAT will contain detailed simulation output, and the file MODEL.LOG will contain a short log report of the model run to be made.

The EXPLORE.DAT file contains the most important information on the simulation, such as production situation to be modelled (potential, nitrogen-limited, water-limited), start time, weather data, and management conditions of the crop.

The file IR72.D92 contains all model parameters that are related to the rice variety IR72.

The file RERUNS.DAT tells the model whether so-called reruns need to be made (explained later).

Note that there is an asterisk (*) in front of FILEI2: when an * is placed in the first position of a text line, this particular text line is not read by the model (it is ignored). As we will see below, the model run we are going to make is for potential production, and the model does not need a soil data file.

All the files listed in CONTROL.DAT can be viewed and edited within the Shell (in either the Input Datafiles or Output Datafiles).

Ex-I.3. Click with your mouse on EXPLORE.DAT of the Input Datafiles. Read Chapter 7.2 of the book ORYZA2000: modelling lowland rice for a detailed explanation of the experimental data file. Scroll through the file and recognize its contents.

In EXPLORE.DAT, the simulation of ORYZA2000 is set up for potential production, no water limitations and no nitrogen limitations. Note the selection of the particular options by putting an * in front of the options to be de-activated. The potential evapotranspiration will be calculated using the Penman method. The water balance model selected is PADDY, but since we run the model without water limitations, this has no meaning now (the calculation of potential evapotranspiration assumes a nonlimited supply of water, hence we don't need to run a water balance in this mode; see also Chapter 4.1 of the book ORYZA2000: modelling lowland rice). The simulation mode is EXPLORATION, which means we do not simulate a specific field experiment. The most important consequence of this option is that the model will start the emergence of the rice crop on the same day the model run will be started. In the case of transplanted rice, this is emergence in the seed bed, whereas in the case of direct seeding, this is emergence in the main field. The start day of the simulation is given by STTIME in the Section 2 Timer data for simulation. In this example, ORYZA2000 will be initialized and start its calculations on day 4 (January 4) of 1992. ORYZA2000 stops automatically when the simulated crop has reached maturity or when the day number specified in FINTIM (FINish TIMe) has been reached. To make sure we reach maturity in the simulation, we put FINTIM at a very high value (1000.).

The weather data and the name of the weather data file is specified in Section 3 Weather station and climatic data for simulation. In this example, we want to simulate the growth of rice at Los Baños, the Philippines in 1992. The weather data for this location and for this year are stored in the file PHIL1.992, which is located in the folder (or directory) 'C:\COURSE\WEATHER\'. Note that the full name of the weather data file is broken down into three components (see Chapter 7.5 of the book ORYZA2000: modelling lowland rice):

·      CNTR denotes the country name (PHIL),

·      ISTN denotes the weather station number (1), and

·      IYEAR supplied earlier in Section 2 Timer data for simulation (1992) of the experimental data file, and in

          the file name indicated with the extension .992.

Scroll down in the file to read that the rice crop we want to simulate is transplanted (Section 4 of the data file Establishment data) at a rate of 5 seedlings per hill and 25 hills per square meter, with 12 days in the seedbed before transplanting (Section 5 of the data file Management parameters).

In Section 6, information on irrigation should be supplied when ORYZA2000 is run with a water balance. This is not the case now, so this section is empty (see the exercises in Chapter IV: Water-limited production for details on this section). Similarly, the nitrogen management in Section 7 is empty, since we do not run ORYZA2000 with a nitrogen balance in this exercise (see the exercises in Chapter III: Nitrogen-limited production for details on this section). In this exploratory example of simulation, we do not have observations or measurements on a real crop from a field experiment, hence Section 8 is also empty (all asterisks in first column).

Ex-I.4. Click with your mouse on IR72.D92 of the Input Datafiles. Scroll through the file and recognize that this file contains parameter values that define the rice variety IR72. We will not study this file in detail here, see the exercises in Chapter II: Potential production for more details.

We now have seen the contents of all the input data files for this model run:

·       CONTROL.DAT defines the output data files and the experimental and crop data files;

·       EXPLORE.DAT defines the production situation and the crop management, and

·       IR72.D92 defines the rice variety IR72.

The weather file PHIL1.992 contains the weather data in 1992 at Los Baños, the Philippines. We are now ready to run ORYZA2000.

Ex-I.5. Click with your mouse on the Run button or the green pointer on the top bar of the screen. A so-called DOS box opens and we see that ORYZA2000 is executed. After simulation, we need to give an <enter> to acknowledge that the run is finished and to close the DOS box.

We are now ready to view the produced outputs. Two output data files (RES.DAT, OP.DAT), one graphic file (CHART.TXT), and two log reports are generated by ORYZA2000.

Ex-I.6. Click with your mouse on OP.DAT of the output data files. The file OP.DAT contains a few summary output data of the simulation. Find the meaning of the variables in the List of variables on pages 215-230 of the book ORYZA2000: modelling lowland rice, and fill out the first part of Table I.1: the columns Explanation/meaning, Unit, and Sim1.

Table I.1.

View ANSWERS from the Tutorial_answer_sheet.pdf file.

The weight of rough rice (WRR14) is the weight of the threshed (but unhulled) grains at a standard of 14% moisture content. The weight of the storage organs (WSO) is the dry weight (0% moisture) of the whole panicle, that is the top part of the stem that carries all the grains. Note that these values are very similar. The total dry weight of all above-ground biomass (WAGT) is the sum of the dry weights of the storage organs (WSO), stems (WST), and leaves (WLV). The weight of leaves consists of the weight of green leaves (WLVG) plus that of dead leaves (WLVD).

Ex-I.7. Click with your mouse on RES.DAT and on Run_0 under RES.DAT of the Output Datafiles. These files contain daily-simulated values of a large number of variables. In Run_0, find the meaning of the variables LAI, DVS and CROPSTA in the variable list. Scroll left-right and top-down through the file and examine some other variables.

The files RES.DAT and Run_0 under RES.DAT contain the same simulated variables, but in different formats. In RES.DAT, the data are presented in text format with a header that recapitulates the main run conditions selected for this run of ORYZA2000. In Run_0, the data are presented in a spreadsheet format. These data can easily be selected and copied into a real spreadsheet, such as Excel, for further manipulation.

The column TIME gives the day number since the start of simulation. Note that all outputs in this simulation run start at day 4, being the start day of simulation (STTIME defined in the file EXPLORE.DAT). The variable DVS gives the development stage of the crop; the value 0 indicates emergence, 0.65 panicle initiation, 1.0 flowering and 2.0 physiological maturity (see also pages 30-31 of the book ORYZA2000: modelling lowland rice). The variable CROPSTA indicates some other key stages of the crops growth cycle: 0 indicates the period before seeding (fallow soil), 1 the day of emergence, 2 the period in the seedbed, 3 the day of transplanting, and 4 the period in the main field.

Ex-I.8. Use the file RES.DAT  (Run_0) and the variables DVS and CROPSTA to complete Table I.1.

Next, we'll explore the graphics option of the FSEWin shell.

Ex-I.9. Click CHART.TXT under Charts.

A new window opens when CHART.TXT is opened. On the left hand side are columns with the same variable names as listed in the file RES.DAT. Each variable can be plotted against another by selecting a hash (#) in the appropriate column: X for the horizontal axis, and Y for the vertical axis (the third axis, Z, is not yet operational). After selecting the desired variables, they are plotted by clicking the mouse in the right-hand side of the window.

Ex-I.10. In the graph window, put a hash (#) in the X-column for TIME, and a # in the Y-column for the variables WAGT, WSO and WLVG. Click on the right-hand side with the mouse and study the graph. Go back to the columns; remove the # in the X-column of TIME and select now DVS. Make the graph. What is the difference between the two graphs you have made? Play around with the graphic option by plotting the leaf area index (LAI), the potential canopy transpiration (TRC) and various other variables against time.

Figure I.1. Simulated potential canopy transpiration (TRC, mm d-1) versus time.

After the graphics, we are ready to quickly examine the last two output files produced:

Ex-I.11. Click with your mouse on MODEL.LOG and WEATHER.LOG of the output data files.

The two log files present some basic information that can be useful when studying the sequence of some model operations or understanding some error messages. At this point, we do not go into further detail in these files.