Cool climate and shorter growing season are the main feature of northern part of Sweden. These features poses a serious challenges to have crops which can survive under low thermal units, and grow well at higher latitudes with longer day length and higher radiation use efficiency. Red clover (Tri-folium pratense L.) is an important deep rooted perennial forage legume crop famous for its high protein feed (Marshall et al., 2017) and high rate of biological nitrogen fixation. Red clover is a native of Sweden and have been cultivated in Sweden from at least 200 years. Management practices, study sites and climatic conditions have significant impact on the quantity and quality of forage. Climate change in the form of increased CO 2 concentration and temperature and changes in rainfall patterns have quite significant differential influences on crop yield and product quality. The effect of mangements, genotypes and environments on red clover in northern Sweden could be studied by the use of crop model such as Agricultural Production Systems sIMulator (APSIM) next generation. This model have not been tested and calibrated for northern part of the world. Therfore, the purpose of this study is to calibrate and evalaute APSIM next geneartion for red clover crop production under nordic conditions and to see how this model can capture effect of radiation use effeciency on drymatter production of red clover crop.