Hello Dr. Sherchand,
I think your first approach should have worked. You separated the
irrigation and fields by year. I don't know exactly why the irrigation data
is not correctly output to the SUMMARY and other files. Most likely some
adjustment is needed to the file X.
There are some things that need correcting, but I don't think these
should have affected the irrigation output. First, Bund height is set under
the *IRRIGATION AND WATER MANAGEMENT section. Set the IDATE, then put IR009
under IROP and the bund height (100) under IRVAL. IAMT is used for fixed
irrigation amounts, not bund height. Second, adjusting NH4 and NO3 to
calibrate the genetic coefficients is not a recommended practice. To
calibrate the genetic coefficient, the genetic coefficients should be the
only unknowns. When NH4 and NO3 are adjusted concurrently with the genetic
coefficients, there is a very large number of combinations of NH4/NO3 and
genetic coefficient values that will match the simulated to the observed
target value. It may be better to estimate the NH4 and NO3 values, enter
the estimates in the initial conditions, calibrate the genetic
coefficients, and recognize that some of the error in the genetic
coefficient is due to the NH4/NO3 estimation process.
I am not aware of any method to estimate NH4 and NO3 from total N.
Perhaps someone else in the Listserve has some ideas.
I hope this helps.
Sincerely,
Richard
At 07:10 PM 8/20/01 -1000, Agriculture Environment wrote:
>Dear all:
>
>I had been in touch with Dr. Richard Ogoshi since a long time. Now I have
become the part of the DSSAT LIST Server. About my problem I want to
contact to Dr. Ogoshi through this facility.
>Dear Dr. Richard Ogoshi:
>
>Thank you very much for the email. The problem I had about irrigation
treatment came this way:
>
>1. I tried to callibrated three years rice experiments 1996, 1997 and 1999
with one expt file. I made one experimental file instead of three and put
Year as variable (Field 1, 2, and 3). Irrigation treatment (IM) were also
1,2,3 and bund height under IAMT was set to 100 and also IRVAL to 100.
With this the irrigation output was reported only from the last year i.e.
1999. And earlier two years 1996 and 1997 did not express. I did this way
because may be this is quicker and management and varieties are almost the
same, except the soil condition may be a bit different. With this the
genotopic coeficient came a bit different and higher that the limit such as
G1. In fact according to manual, this value (G1) should remain around 55
although the range is from 10 to 500. To solve this I had to make some
adjustment in the NH4-N and NO3-N inputs in the Initial Condition (IC). The
1997 NH4-N goes very high 24.0 ppm to get the same genotypic coefficent to
be callibrated.
>
>2. Later I changed the file structure the other way. I made three
separate file 1996, 1997 and 1999. I made the same input for irrigation.
Now I can get the irrigation output getting expressed in each file output.
Also the NH4-N in 1997 could be lowered to 11ppm to get the same genotypic
coefficient callibrated.
>
>1. My concern and query is why the outputs are different from the above
two approaches ? Do you think that the first approach is wrong or I have to
make additional adjustment in the file or in the simulation control? Please
suggest.
>
>2. My experience shows that NH4-N and NO3-N inputs in the IC are very
sensitive. In our condition, usually we donot analyse these Ns. Our usual
practice is to calculate the total N only. Can you suggest on this?
>
>Thank you
>
>Kishore Sherchand
>
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