Comparison on environmental impacts of cereal and forage production in the Loess Plateau of China: Using life cycle assessment with uncertainty and variability analysis

The increasing demand for high-quality animal protein calls for parts of cereal cropping systems converting to forage or forage-livestock integrated systems. This study aimed at evaluating potential environmental impacts of this transition at the farm level on the Loess Plateau of China through a life cycle assessment (LCA) approach. Four dominating crops: alfalfa, wheat, grain maize and silage maize were studied based on the ten impact categories. Based on standard unit land area (1 ha) and timestamp (2018–2020) settings, alfalfa production indicated the lowest environmental impact in nine categories compared to other crops, while wheat indicated better performance in seven of ten impact categories than other crops except alfalfa. With respect to the environmental loads of grain maize and silage maize production, both systems were very comparable. Because of the common adoption of open-land burning of straws (mainly for fuel and winter heating) in the local region, the respiratory inorganics and photochemical oxidant formation potential impact of alfalfa and silage maize per hectare produced is much lower than those of wheat and grain maize. Great differences in environmental impacts between the two types of cropping systems (cereal vs forage) indicate that transitioning from cereal to forage production should effectively reduce air pollution and enhance environmental sustainability on the Loess Plateau. Besides, uncertainty and variability of LCAs results were analyzed in this study.