Hello Jean-Philippe:
I ran some simulations a while ago using the soybean model in DSSAT for soils typical of Prince Edward Island, and found that when I decreased soil depth below 90 cm, it started to affect my yields quite significantly. For example, 90, 70, 60 and 50 cm depth soils resulted in yields of 2495, 2090, 1594 and 1219 kg/ha respectively. I suspect that water stress was likely the cause of the reduced yields, so under a warmer/drier climate than PEI, the model may be even more sensitive to soil depth.
I would suggest you do some sensitivity tests to determine how sensitive your model results are to soil depth using some typical data for Quebec soils. One way would be to use the data to 60 cm and then make assumptions about the soil parameters below that depth. Varying these assumptions systematically would give you a good idea about how important it would be to get accurate information for depths below 60 cm. I suspect that some of the soil survey people in Agriculture and Agri-Food Canada at St. Foy Research Centre could give you some rough values for below 60 cm for some typical soils.
Hope this is helpful.
Sincerely,
Andy Bootsma
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Andrew Bootsma, Agro-climatologist
Agriculture and Agri-Food Canada
Eastern Cereal and Oilseed Research Centre
K.W. Neatby Bldg., Rm. 4129B
960 Carling Ave.
Ottawa ON CANADA K1A 0C6
Tel: (613) 759-1526
Fax: (613) 759-1924
E-mail: [log in to unmask]
Internet: http://res.agr.ca/ecorc/staff/boot-a.htm
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>>> [log in to unmask] 11/26/01 03:48PM >>>
Dear DSSAT users,
I'm using the DSSAT suit of crop models to evaluate the impacts of
CO2-induced climate change on agricultural yields in the province of Quebec,
Canada.
because I'm trying to evaluate the impacts on crop yields for all of
Quebec's agricultural region, I'm not working on some specific sites. As
such, I have very general soil data for every region.
My problem is that the only analysis of the soils caracteristics that was
done for the whole of quebec's agricultural territory did not go deeper than
60cm. Hence, my soil profiles contain only 3 layers and are 60cm deep.
I wanted to know if that would affect the final simulated yields in a
significant manner and, if so, if there is any way to solve this problem?
thank you for your help,
Sincerely,
Jean-Philippe Brassard
Departement de Geographie
Universite de Montreal
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