Climate Change, Soil Saturation, and Risk of Yield Penalties to Key Cereal Crops: A Neglected Issue in Agri-Food System Adaptation

Abstract

Soil water or moisture balance drives essential rhizospheric and physiological processes that culminate in yield formation in crop plants. Climate change threatens to alter temperature and precipitation patterns and thereby the hydrological processes underpinning soil moisture balance and related stresses such as saturation or deficit. While considerable volume of literature exists on soil moisture deficits under the climate change, the same cannot be said of soil saturation (the transitory water content of the soil when nearly all its pore spaces are filled with water and the water potential is close to zero). Few crop plants can survive soil saturation exceeding few days. This chapter demonstrates the potential effects of soil saturation on crop yield penalties under projected climate change. Cereals are the main dietary energy source in human diets and animal feed formulations. Hence, future yield penalties in cereals can be detrimental to global food security. Cereals can be highly sensitive to abiotic stresses such as heat stress and soil water deficit or saturation at specific growth stages. The FAO AquaCrop model was used to simulate biomass production and yield of the barley genotype Westminster for all UK administrative regions in the 2050s. The simulation was done for spring conditions, under the low and high climate change emission scenarios (LES and HES), respectively. Yield penalty was expressed as the mean percentage of all yearly yield reductions in the 30-year time slice relative to the 10th percentile yield for the entire time slice. The results showed that yield penalties were more extensive under the HES than the LES. The ranges of yield penalties were 5–76% (HES) and 5–41% (LES) under varied durations and severities of soil saturation. It is concluded that, due to climate change, soil saturation can potentially cause substantial yield penalties, especially in highly sensitive crops and is, therefore, worthy of research, policy and practical attention. Although soil saturation stresses could be less frequent compared to those of heat and soil moisture deficits, yield penalties under the former could, in some cases, be larger than the latter and could occur as a surprise. It is recommended that further studies on potential effects of soil saturation on crop yield penalties be integrated in the suite of research and measures for adaptation of key crops such as cereals, which are the main source of energy in human diets and animal feed.