Agro Fossil Free - Multi-Criteria Assessment of the Economic and Environmental Sustainability Characteristics of Intermediate Wheatgrass Grown as a Dual-Purpose Grain and Forage Crop

Opis ogólny

Kernza® intermediate wheatgrass [IWG; Thinopyrum intermedium (Host) Barkworth & Dewey] is a novel perennial cool-season grass that is being bred for use as a dual-purpose grain and forage crop. The environmental benefits of perennial agriculture have motivated the development of IWG cropping systems and markets for perennial grain food products made with Kernza, but the economic viability and environmental impact of IWG remain uncertain. In this study, we compared three-year cycles of five organic grain production systems: an IWG monoculture, IWG intercropped with medium red clover, a continuous winter wheat monoculture, a wheat–red clover intercrop, and a corn–soybean–spelt rotation. Economic and environmental impacts of each cropping system were assessed using enterprise budgets, energy use, greenhouse gas (GHG) emissions, and emergy indices as indicators. Grain and biomass yields and values for production inputs used in these analyses were obtained from experimental data and management records from two separate field experiments conducted in New York State, USA. Grain yield of IWG averaged 478 kg ha−1 yr−1 over three years, equaling approximately 17% of winter wheat grain yield (2807 kg ha−1 yr−1) over the same period. In contrast, total forage harvested averaged 6438 kg ha−1 yr−1 from the IWG systems, approximately 160% that of the wheat systems (4024 kg ha−1 yr−1). Low grain yield of IWG greatly impacted economic indicators, with break-even farm gate prices for Kernza grain calculated to be 23% greater than the current price of organic winter wheat in New York. Energy use and GHG emissions from the IWG systems were similar to the annual systems when allocated per hectare of production area but were much greater when allocated per kg of grain produced and much lower when allocated per kg of biomass harvested inclusive of hay and straw. Emergy sustainability indices were favorable for the IWG systems due to lower estimated soil erosion and fewer external inputs over the three-year crop cycle. The results show that the sustainability of IWG production is highly dependent on how the hay or straw co-product is used and the extent to which external inputs can be substituted with locally available renewable resources. Integrated crop–livestock systems appear to be a viable scenario for the adoption of IWG as a dual-use perennial grain and forage crop.