SUMMARY
In the study the previously calibrated LINGRA-N model was used for a long term simulation (1964–2013) of the herbage dry matter yield (GRASS) and growth analysis of Cock’s foot (Dactylis glomerata L.) in Jablje. Changes in the yearly GRASS variability are reflected in the appearance of outliers in the second half of the study period. The biggest reductions in GRASS are seen in the years 1992, 1993 and 2003. These are the driest years according to meteorological variables (high maximum and minimum air temp eratures, low precipitation) and also according to the simulations, with the lowest reduction factor for crop growth due to drought. The potential yield (YIELD) is not linearly dependent on meteorological variables. Some growth compone nts were compared on a daily basis in a dry year (1993) and an average year (1994). In 1993, for instance, 53 % of photosynth etically active radiation was intercepted, against 75 % in 1994. Seasonal development of the actual soil moisture content was linked to the development of the leaf area index and consequently to the mass of green leaves, to the roots mass, to the mass of dead leaves and to GRASS. The results highlight the need for further research, on field and with simulations. As re gards the latter, we have to keep in mind that they inevitably involve various uncertainties.