MODELING GROWTH AND NITROGEN-BALANCE OF BARLEY UNDER AMBIENT AND FUTURE CONDITIONS

According to current scenarios, atmospheric CO2-concentration ([CO2]) and average air temperature will rise in the future. The predicted lon ger growing season in Finland would imply that more productive cultiva rs and even new crop species could be grown. Moreover, higher [CO2] is also likely to increase dry matter production of crops. This study an alyzed the growth of spring barley (Hordeum vulgare L.) under ambient and suggested future conditions, and its response to N fertilization. Model simulations of soil temperature and of snow accumulation and mel ting were also studied. The calibration and validation results showed that the model performed well in simulating snow dynamics, soil temper ature, the growth of barley, and the response of crop growth to N fert ilization under present conditions. According to the simulation runs, if a cultivar was adapted to the length of the growing period, the inc rease in dry matter production was 23% in a low estimate scenario of c limate change, and 56% in a high estimate scenario under a high level of nitrogen fertilization. The simulation study showed that the shoot dry weight increased by 43%, on average, under high N fertilization (1 50-200 kg N/ha), but by less (20%) under a low level of N (25-50 kg N/ ha) when the conditions under a central scenario for the year 2050 wer e compared with the present ones.