Future projections of European maize yields using AquaCrop with an adaptive growing season.

Securing maize crop production is essential in our changing world. However, it remains unclear to what extent climate conditions and farmers' practices, such as fertility management and irrigation, can impact future maize crop production in Europe. Here we use the AquaCrop model v7.2 in a spatially distributed setup to estimate yields, yield gaps, growing cycles, and water productivity over a 30-year baseline period (1985-2014), and a near-future period (2030-2059) under a range of climate scenarios, forced with meteorological data from the Inter-Sectoral Impact Model Intercomparison Project (simulation round 3). We define a generic maize crop with a temperature-dependent sowing date and growing stages, allowing for acclimatization of the growing cycle, in contrast to some earlier climate impact assessments. The results show that a warmer climate will lead to earlier sowing dates and shorter growing seasons, keeping future yield and yield gaps for rainfed maize relatively unchanged from the baseline. Furthermore, the area of profitable rainfed maize production may shift north and expand. In contrast to the marginal impact of climate change on near-future maize yield, removing fertility stress has the potential to increase average yields by 1.5 ton/ha (mainly in the north). An additional gain of 2 ton/ha can be obtained by optimizing irrigation in the southern regions that are not completely unsuitable for rainfed maize production. For irrigated maize in the south, the stable future yield projections are accompanied with increased water productivity, again due to an earlier and shorter growing season.