Future changes in crop yield over Poland driven by climate change, increasing atmospheric CO₂ and nitrogen stress

CONTEXT: Crop production is strongly affected by climate -related factors that are predicted to become more severe in the future due to significant changes in temperature, rainfall patterns, and increase in the intensity and frequency of extreme events. Understanding potential future crop yield response to a changing climate is of great importance for food production stability and safety. OBJECTIVE: The overall objective of this study is to assess the impact of projected climate change on crop yield in Poland. METHODS: This study employed an agro-hydrological Soil and Water Assessment Tool (SWAT) model forced by EURO-CORDEX downscaled and bias -corrected climate model outputs to simulate future changes in yield of spring barley (Hordeum vulgare), rapeseed (Brassica napus), maize silage (Zea mays), and potato (Solanum tuberosum) over Poland driven by climate change, an increase in atmospheric CO2 concentrations, and plant growth stress factors. We looked into two future horizons: near future (NF; 2041-2060), and far future (FF; 2081-2100) under two different Representative Concentration Pathways (RCP4.5 and 8.5). RESULTS AND CONCLUSIONS: Climate projections revealed that by the end of century, Poland will experience an increase of mean precipitation (by up to 10.3%) and mean temperature (+3.4(degrees)C) under RCP8.5. We tested two different nitrogen fertilisation scenarios under changing climatic conditions, namely auto fertilisation which adjusted the nitrogen doses according to actual plant requirements in each climatic scenario, and constant doses corresponding to current use throughout the entire simulation period. The results showed that crops in Poland will experience an increase in nitrogen stress and a decrease in water stress in the future. Temperature stress is projected to increase for spring barley, rapeseed, and potato, and decrease for thermophilic maize silage. Auto fertilisation scenario application that eliminated nitrogen stress in future horizons resulted in a significant increase in yield of all crops under consideration. The comparison of the RCP scenarios showed a higher increase for RCP8.5, reaching 13% for NF and 17% for FF as an average value for all crops. For RCP4.5, the corresponding values were 10% (NF) and 13% (FF). Nitrogen stress reported under the constant nitrogen rate scenario offseted potential yield increase in future horizons caused by elevated CO2.The multi -annual average yield of the analysed crops in future increased by <5%. SIGNIFICANCE: Our study indicated that future changes in crop yield in Poland are mostly related to CO2 enhancement, and benefitting fully from that will require an adjustment of nitrogen fertiliser rates. Otherwise, a potential increase in biomass production will be restricted by nitrogen availability.