WOFOST: crop growth simulation model - 2nd part

Abstract

WOFOST (WOrld FOod STudy) model is with its user friendly preface very simple to use. It has five tabs: general, crop, weather, soil and reruns, where we determine the calculation parameters. The simulation can base on potential, water-limited or nutrition-limited conditions. Crop parameters have to be quite well known or we can choose pre-determined crop from the model, similar it is with the soil data. There is also possible to set the date of sowing and harvesting (maturity), but we can let the model to choose the more appropriate ones, which are based on meteorological conditions. The format for meteorological data is determined, so we have to prepare them correctly. WOFOST model calculates among others phenological stages, dry weight of roots, leaves, stems and storage organs, total above ground production, harvesting index, evapo(transpi)ration, assimilation, maintenance respiration, actual root zone depth, soil moisture and dry/wet days.

Our calculations for maize (pre-defined) give us the estimation of the effect of drought on crop yield for the period 2003-2006. Year 2003 was extremely dry, dry was also 2006, 2005 was moderate and 2004 was wet. Major differences in soil moisture between years came out at the end of May. Maize reached maturity the earliest in 2003 and the latest in 2004. At the beginning of the growth season there is higher soil evaporation than transpiration, in the middle is higher transpiration and at the end again soil evaporation. Crop production is also depending on water conditions, so it is much smaller in 2003, a bit bigger in 2006, in 2004 and 2005 it was quite the same - there were no problems with the water shortage. We have also shown that the number of dry days strongly depends on the soil type; there are much more dry days on the soil with low water holding capacity. In general, the driest years were 2001, 1992, 1971, 1988, 2003 in 1993 (until 2005).