Modelling the variability of UK sugar beet yields under climate change and husbandry adaptations

In the future, UK summers are likely to be warmer and drier. Modelling differential water redistribution and uptake, we assessed the impact of future drier climates on sugar beet yields. Weather was generated for 1961-1990 (BASE) and predictions based on low- and high-emission scenarios (LO, HI) described in the most recent global climate simulations by the Hadley Centre, UK. Distributions and variability of relative soil moisture deficit (rSMD) and yield gap (drought-related yield loss, YG(dr) = 1-actual yield/potential yield), and sugar yield were calculated for different time-lines using regional weather, soil texture and management inputs. The rSMD is estimated to exceed the senescence threshold with a probability of 75% (2050sLO) to 95% (2080sHI) compared with 65% (BASE). The potential yield loss, YG(dr), is likely to increase from 17% (BASE) to 22% (2050sLO) to 35% (2080sHI). However, increasing potential growth rates (CO2 x temperature) cause average sugar yields to rise by between 1.4 and 2 t ha(-1) (2050sLO and 2050sHI respectively). Yield variation (CV%) may increase from 15-18% (BASE) to 18-23% (2050s) and 19-25% (2080s). Differences are small between regions but large within regions because of soil variability. In future, sugar yields on sands (8 t ha(-1)) are likely to increase by little (0.5-1.5 t ha(-1)), but on loams yields are likely to increase from 11 to 13 t ha(-1) (2050sHI) and 15 t ha(-1) (2080sHI). Earlier sowing and later harvest are potential tools to compensate for drought-related losses on sandy soils.