engleski

Modelling on climate change impacts on maize yield in Croatia

Analyzing agricultural systems and modelling the potential impact of climate change on crop production is a very important topic, particularly nowadays as food supplies are becoming scarcer in many parts of the world and the need for all people to have sufficient food. As climate changes of different intensity in various regions were detected, there is a need for researching them at regional and national levels. The main application of the crop models is in climate change impact research on agriculture. Maize, winter wheat and spring barley are very often used for scientific investigations in the central and southeastern Europe using the different crop-weather models. Maize is one of the most important agricultural crops in Croatia and its vegetation period coincides with the warm season, from May to October. Therefore, it was decisive factor in the crop type choice for the research of climatic changes impact on maize yields in Croatia. The meteorological data of the Zagreb-Maksimir station, which is situated in the central Croatia, and pedological data, physiological and morphological data obtained in the field maize experiment in Zagreb have been analyzed. The Decision Support System for the Agrotechnology Transfer (DSSAT) model, as one of the most applied crop model in the world, has been used for the investigation of maize production in the present climate since 1949. The linear trends of model outputs and Mann-Kendall test indicated a significant earlier onset of silking by 1.4 days/10 years and physiological maturity by 4.5 days/10 years in the central Croatia which started in mid-1990s. Moreover, a significant decrease in maize yields by 216 kg/ha in 10 years is also obtained. The yield trend became significant at the beginning of the 21st century. There was a slight decrease in kernel mass (0.01 g/10 years) and aboveground biomass (122 kg/ha in 10 years). A positive trend in evapotranspiration and soil evaporation (around 3 mm/10 years) and in runoff (0.6 mm/10 years) has been noticed during the vegetation period. Thus, significant shortening the vegetation period by 5 days and reduction in maize yield by 2% have been estimated in the present climate. Further investigation involved the generation of synthetic meteorological series representing the changed climate by stochastic weather generator Met&Roll and different climate change scenarios. The climate change scenarios were prepared by the pattern scaling technique using the following global climate models: ECHAM, HadCM and SCIRO. The middle climate sensitivity is a 2.5°C increase in global temperature to equilibrium doubled carbon dioxide. When the three climate change scenarios had been prepared, the stochastic weather generator Met&Roll was applied to generate a 99-years synthetic meteorological series. Using the synthetic meteorological series in the DSSAT model, the indirect effect of increased carbon dioxide on maize yields in the central Croatia has been estimated for different climate change scenarios for years 2050 and 2100. All climate change scenarios for the 21st century projected a shorter growing season and a reduction in maize yields. The maize vegetation period in the central Croatia would be 39 days shorter for ECHAM, 42 days for HadCM and 34 days shorter for CSIRO, which would result in 14%, 25% and 22% smaller yields for maize, respectively, at the end of the 21st century. Both shifting planting date and using hybrids with longer growing season would be beneficial for maize productivity in the changing climate. The experience of farmers and agronomists in the central Croatia shows they have already been adapting maize production to the warmer weather conditions in the last decade. The usual hybrids in the central Croatia were hybrids with a medium growing season, but nowadays hybrids with a longer growing season are increasingly used. In the future, thus, Croatia could belong to the area of decreased maize yields. Some adaptation options like shifting to an earlier sowing date and selecting hybrids with longer growing season and resistant to drought could be an appropriate response to offset the negative effect of an increase in temperature. The present study could help in optimizing and improving agricultural management in order to adapt to changes in climate and weather conditions in Croatia.

climate change ; crop model ; maize ; Croatia

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