Climate change impacts on two European crop rotations via an ensemble of models

Continuous long-term simulations of an ensemble of nine crop models covering the 1961–2080 period was employed to assess the expected impacts of climate change on the crop yield and water use for distinct crop rotations (CRs) in Europe. In this study, the likelihood of changes in two differently managed CRs (conventional and alternative) involving four important field crops (winter wheat, spring barley, silage maize, and winter oilseed rape) was assessed. The conventional agricultural practice (CR1) included only mineral fertilization with the removal of crop residues after harvest. The alternative agricultural practice (CR2) included cover crops and the application of mineral and organic fertilizers, with crop residues retained in the field. The simulations covered six sites in five European countries (Mühldorf and Müncheberg in Germany, Ukkel in Belgium, Ødum in Denmark, Milhostov in Slovakia and Lednice in Czechia) based on two distinct soil profiles (universal soil and site-specific soils). The universal soil was the same across all the sites, while the site-specific soils were typical of each region. Eight transient climate change scenarios (4 general circulation models (GCMs) under representative concentration pathways (RCPs) 2.6 and 8.5) were used to capture the possible evolution of future climatic conditions. Compared with those during the 1962–1990 period, the ensemble projections for the 2051–2080 period indicated average increases in the annual yields of all crops of 0.7 t/ha (RCP 2.6) and 0.8 t/ha (PCP 8.5) under both CRs and soil types. Under most climate change scenarios, the crop model ensemble projections of the winter wheat and winter oilseed rape yield increases agreed for CR2 but not for CR1. For spring barley, the simulated increase was more sporadic, with no significant difference between CR1 and CR2. In regard to silage maize, the changes in the simulated yields depended on site-specific climatic conditions. If the same varieties were planted in the future, yield reductions would be expected, except at the Ødum site, where the silage maize growth conditions would remain satisfactory, regardless of the CR and soil type. The results indicated greater cover crop biomass production, which could affect the long-term soil water balance and groundwater replenishment. The crop model ensemble further indicated a greater spatial variability in the yield can be expected, which is likely caused by the expected increase in the air temperature and not by the expected increase, or even decrease, in the total precipitation and increases in the actual evapotranspiration under climate change at all sites. This trend was greater under CR2 and could affect the long-term soil water balance and soil regime in the case of rainfed agriculture.