Impacts of climate change on maize irrigation in the north-west of Italy and possible adaptation strategies

FAO estimates that by 2050 agriculture will have to increase its production worldwide by almost 50% compared to 2012 to be able to satisfy the global demand for food, livestock fodder and biofuels. Climate change brings urgency and uncertainty to this problem. It is fundamental to implement effective adaptation strategies for agricultural practices but, to do so, regional and local studies about the potential impacts of climate change are needed. In this work, a local impact study is performed on an area located in the north-west of Italy, which already suffers from irrigation water supply problems. The final objective is to obtain useful estimates for the future implementation of adaptation strategies. To reach this objective, a daily-scale hydrological crop model is used to compute temporal series of daily actual evapotranspiration and daily irrigation requirements from 2006 to 2055, considering two future climate scenarios (RCP2.6 and RCP8.5). The crop analyzed is maize since it is the most present crop in the area in terms of fraction of irrigated utilized agricultural area. The results show that summer is the critical season for maize development because if not irrigated, it suffers from water stress from June to September. This means that, at the study site, maize must be irrigated to secure a proper production. In the future, there is a wide range of possibilities depending on the future climate scenario examined. Considering RCP2.6 scenario, the irrigation requirements are projected to decrease from 2006 to 2050. On the contrary, under RCP8.5 hypothesis the irrigation requirements will increase in the future compared to the present values, mainly due to the reduction of total summer precipitations and the rise of summer temperatures. However, the inter-annual variability of the results from both the climate scenarios is high. Two adaptation strategies are analyzed, trying to reduce the projected irrigation requirements. The early sowing of maize demonstrates to be a possible effective strategy, since it allows a decrease of the water needs in every case, with peaks of over 20% of reduction. On the other hand, the second adaptation strategy, substituting maize with alternative crops, does not give the expected benefits. Wheat and potatoes were chosen as possible alternatives because they are both already cultivated at the study site, and they have a similar crop calendar to maize. However, the projected irrigation requirements for these two crops results to be higher than maize’s.