Rainfed crop production challenges under European high-latitude conditions

Global warming is likely to prolong the growing season at high latitudes where the brevity of the growing season currently limits crop growth and yields. A longer growing season, elevated atmospheric carbon dioxide (CO2), dedicated plant breeding, and adjusted agronomic practices could open new avenues to increase yield potential while reducing risks of various abiotic stresses such as inadequate precipitation. We used statistical and simulation modelling approaches to determine whether future estimates for elevated yield potentials match projected changes (according to the high-emission SRES A2 scenario) in precipitation patterns and volumes, essential prerequisites for high-latitude rainfed agroecosystems. The statistical approach used long-term data sets to estimate future changes in yield potentials resulting from extension of the growing season and new, better adapted cultivars through plant breeding. Estimated increases in potential yield and biomass were 20–54 kg ha−1 per annum for grain or seed yield, depending on crop, excluding the effects of elevated (CO2). We also applied a crop simulation approach, using the WOFOST model, with barley (Hordeum vulgare L.) as a test crop, to simulate the impact of changing mean climate and the CO2 fertilisation on biomass development and yield formation under optimal nutrient supply, favourable soils, and complete plant protection. Elevated CO2 alleviated the drought effects. However, drought risk increased as the projected increases in precipitation seemed insufficient to meet the increasing needs of the potentially higher crop biomasses. Therefore, irrigation systems need to be developed to realise the future higher yield potentials in northern European agricultural systems.