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

Abstract

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.

Intercropping legumes and intermediate wheatgrass increases forage yield, nutritive value, and profitability without reducing grain yields

“…The benefits of intercropping IWG with legumes were more related to an improvement on nutritive value than on the amount of total forage harvested. Although previous studies had shown increases in the total forage harvested in IWG intercropped with red clover (Favre et al, 2019;Law et al, 2022); in our experiment red clover biomass production did not compensate for the decrease in IWG biomass, resulting in similar total forage yields. The most promising legume to increase the total forage was Kura clover when it was planted with IWG together in the spring even though the greatest differences were seen after the first grain harvest (i.e., fall of the first grain production year and summer of the second grain production year).…”

“…Intercropping IWG with red clover has consistently increased the nutritive value of the summer and fall forage and tripled the amount of available forage in the fall (Favre et al, 2019), positively affecting the revenue perceived by the farmers. In fact, it has been seen that higher forage yields achieved by IWG-legume intercropping systems reduce the Kernza grain price required to be profitable (Law et al, 2022). Although Kernza R grain markets are in a price discovery phase, estimating potential net returns could be useful to compare different cropping systems.…”

Reductions in soil water nitrate beneath a perennial grain crop compared to an annual crop rotation on sandy soil

“…Dewey] is a perennial cool-season grass being domesticated to produce a grain marketed as Kernza R (DeHaan et al, 2018) with the first commercial variety, "MN-Clearwater, " released in 2020 (Bajgain et al, 2020). The crop has potential to provide economic return for producers (Hunter et al, 2020a,b;Law et al, 2022) while reducing NO − 3 leaching compared to corn (Jungers et al, 2019). Intermediate wheatgrass initiates growth earlier in the season than warm-season forage and bioenergy grasses and is thus better able to reduce NO − 3 -N losses early in the season (Jungers et al, 2019) when losses are typically the highest in the Upper Midwest (Randall and Mulla, 2001;Crews and Peoples, 2005).…”

Perennials as Future Grain Crops: Opportunities and Challenges

“…These "yield-gap" scenarios may be associated with soil degradation, strong disease pressure, or low commodity prices, combined with high input costs making production uneconomic, and could complement existing agricultural practice. Therefore, the reduction in input costs, the long-term environmental benefits, and potential dual-use options associated with perennial grain crops, including intermediate wheatgrass, could offset their lower productivity, for which economic analysis has begun (Law et al, 2022).…”

“…When questioned about their motivations to trial intermediate wheatgrass, growers indicated that their primary areas of interest were improved soil health and microbial communities, reduced tillage requirement, the value of the crop in intercropping and weed suppression, and general interest in the value of perennials on-farm (Lanker et al, 2019;Meijer, 2020). Additionally, following grain harvest regrowth of leaves and stems may be used for grazing livestock, forage, hay, or bedding, or as biomass for biofuel production, potentially increasing the economic return, while the crop's extensive root system would improve soil structure (Ryan et al, 2018;Law et al, 2022).…”