MCREW

Making a Yield Calibration Run


Differences in crop management by producers or local climate variances may result in crop yields, generated by WEPS, that do not reflect the actual yields observed by a producer. WEPS provides a method to "calibrate" yields and associated crop residue biomass from WEPS so that they more accurately reflect those of individual producers or a county as a whole. The following steps describes how to make a yield calibration run.

a) Within MCREW, press the ‘Yield Calibrate' button to display additional columns related to the crop yield calibration function in WEPS. When the columns are displayed, the ‘Yield Calibrate' button is outlined in red .

b) Within MCREW, select the crop (or crops) that you want to calibrate by setting the ‘Yield Calib. flg' column value to ‘1' for the respective row the crop planting operation is in. Be sure to "tab" or press "enter" after putting that number in the cell to ‘register' the flag.

c) Fill in the desired ‘Target Yield' for the selected crop(s). Note that the units and the moisture content this yield will be reported in are displayed. (Do NOT change the yield units or yield water content values. Doing so will not have the desired affect within the model at this time. In the future, we expect that this functionality might be made available to the end user). Again, be sure to "tab" or press "enter" after entering the desired target yield value into the cells.

NOTE: More than one crop can be selected for simultaneous yield calibration. However, the algorithms used do not guarantee that a solution will be found when multiple crops are specified for calibration. In practice though, we have found it to work well in most situations.

d) Save the rotation management file in MCREW. Currently, this can be done by: i) pressing the 'Save' icon , ii) via the ‘File > Save' menu option, or iii) using the ‘Ctrl-S' keyboard shortcut.

e) Exit MCREW. This can be done either by: i) clicking on the "close" button in the top right corner of the MCREW window frame or ii) via the ‘File > Exit' menu option. Note that if one forgets to save the management file before attempting to exit MCREW, the user will be notified and given the opportunity to do so before exiting MCREW.

f) Click the ‘Make a Yield Calibration WEPS Run' via the ‘Run' menu option on the main screen. The shortcut ‘Ctrl-C' will also work if the main WEPS screen has focus.



g) After the Calibration Run has completed, a popup dialog window will appear that displays the 'Calibration Factors' for each crop selected for calibration (see figure above). One can then enter these values back into the management file using MCREW - (remember to press the yield calibration button to display the extra crop calibration parameter columns). For each crop that had been "calibrated", enter the new values into the ‘Biomass Adj. Factor' column. The biomass adjustment factor determined for each crop is also written into the ‘notes' file for the calibration run.

h) To save these changes into a "newly calibrated" crop record file, one must use the "drilldown" feature in the appropriate crop cell to display the list of crop parameters. The user can then save these parameter values to a new "crop record" file using the ‘Save As' function. Appropriately rename the newly calibrated crop record. Once saved, the user can then select and insert that crop record into any WEPS management file using MCREW.