>Sutisa and other DSSAT users:
>The DSSAT models do not respond to phosphorus. Yes, there are
>features in XBUILD to input the fertilizers that include phosphorus,
>but this is for future use. We have a group working on phosphorus
>version of the model, but that version may not be available for 2
>years or more. Even when it is available, it will require testing
>in diverse regions to improve confidence that it works. So, please
>stay in touch with us, if you have good data sets, with both soil P
>measurements, plant P measurements, and plant growth, along with P
>fertilizer treatments. Such data may be very helpful for testing
>the future DSSAT models for maize or other crops.
>
>Meanwhile, if you want to simulate the relative effect of
>phosphorus, I recommend that you use different soils for each of
>your P fertility treatments, that are identical in all respects,
>except differing in the SLPF value (the soil fertility value on the
>5th line of each soil file). With the current model versions, the
>SLPF is used to describe the other soil-related fertility aspects
>other than N or water supplying abilities, to include nematode
>stress. For example, the default value of 1.00 is reasonable for
>highly fertile soils in the Midwestern USA, but values of 0.90 are
>typical in southeastern USA, values of 0.70 to 0.80 are common in
>West Africa and India. I have shown line 5 with values for SLPF
>from 1.00 to 0.70. Calibrate the initial SLPF value to the slope of
>dry matter accumulation for the zero P treatment (or to give you the
>end of season final biomass, if you lack time-series data). Then,
>adjust the value of SLPF up for each P fertilizer treatment. Mostly
>ignore grain yield in this analyses, although that hopefully should
>come along with the P-SLPF effect on total crop (top) mass.
>
>*IBMZ910023 IBSNAT -99 151 Norfolk Loamy Sand
>@SITE COUNTRY LAT LONG SCS FAMILY
> Florence,SC USA -99 -99 Norfolk Loamy Sand
>@ SCOM SALB SLU1 SLDR SLRO SLNF SLPF SMHB SMPX SMKE
> -99 0.14 5.0 0.60 60.0 1.00 1.00
> IB001 IB001 IB001
>
> -99 0.14 5.0 0.60 60.0 1.00 0.90
> IB001 IB001 IB001
>
> -99 0.14 5.0 0.60 60.0 1.00 0.80
> IB001 IB001 IB001
>
> -99 0.14 5.0 0.60 60.0 1.00 0.70
> IB001 IB001 IB001
>
>Good luck with your modeling,
>
>Ken Boote, crop physiology
>University of Florida
>
============================================
Gerrit Hoogenboom
Professor &
Coordinator of Research, Extension and Instruction
Department of Biological and Agricultural Engineering
The University of Georgia
165 Gordon Futral Court
Griffin, Georgia 30223-1797, USA
1-770-229-3438 (voice); 1-770-228-7218 (fax)
mailto:[log in to unmask]
www.Georgiaweather.net
www.GerritHoogenboom.com
============================================
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