Warm-climate, legume-grass forage mixtures versus grass-only swards: An ecosystem services comparison

Abstract

Integrating warm-climate forage legumes into grass monocultures has received significant research attention during the past 70 years, but widespread adoption by end users has been elusive. The objectives of this review are to provide historical context regarding legume use in warm-climate grasslands; synthesize the current literature addressing contributions to grassland ecosystem services of warm-climate, grass-only vs. legume-grass mixed swards; and consider how to achieve more widespread adoption of legume technology in warm climates. For this review, warm-climate grasslands are considered those in areas between latitudes 30° N and 30° S, where C4 perennial grasses dominate. The literature suggests measurable advantages in animal performance, soil carbon accumulation, and nutrient cycling of legume-grass mixtures are most likely when grass-only swards receive little or no N fertilizer. Advantages are less or may disappear when mixtures are compared with grasses receiving high N fertilizer rates. In contrast, amelioration of greenhouse gas emissions is often most pronounced for mixtures when compared with grass-only swards receiving high rates of N, because of the magnitude of N fertilizer effects on emissions. Going forward, there is need to focus on selecting for, and thoroughly documenting legume persistence, achieving low-risk and affordable legume establishment methods, assessing compatibility of legumes in mixture with grasses prior to legume cultivar release, emphasizing adoption of both legume species and optimal management practices, and recognizing scientists must assume a larger and more intentional role in encouraging adoption by end-users of research innovations, in addition to our traditional role in technology and product development.

Species richness and functional diversity enhance winter annual forage productivity and nutritive value

“…Taken together, our results from Gainesville and Marianna agree with the assertion that the inclusion of certain functional groups can disproportionately affect forage nutritive value (Brink et al., 2015). The dominance of grasses in all treatments at Gainesville likely explains why we did not observe an effect of increasing functional diversity on forage shoot N concentration at this location (Figure S1a) since legumes are associated with greater N concentration and crude protein (Brown et al., 2018; Sollenberger & Dubeux, 2022). In Marianna, the influence of legumes, which accounted for approximately 25% or more of the proportion of harvested biomass (Figure S1b), increased forage shoot N concentrations.…”

“…T A B L E 5 Intercept and treatment coefficient estimates, standard errors, and 95% confidence intervals from the model for total average winter annual forage shoot nitrogen (N) concentration at two northern Florida locations. treatments at Gainesville likely explains why we did not observe an effect of increasing functional diversity on forage shoot N concentration at this location (Figure S1a) since legumes are associated with greater N concentration and crude protein (Brown et al, 2018;Sollenberger & Dubeux, 2022). In Marianna, the influence of legumes, which accounted for approximately 25% or more of the proportion of harvested biomass (Figure S1b), increased forage shoot N concentrations.…”

Sward characteristics, herbage accumulation and nutritional value of elephantgrass based mixed with or without pinto peanut

“…A similar response was also obtained in a mixed pasture with elephantgrass and red clover (Diehl et al 2014). It is noteworthy that the presence of pinto peanut, in addition to increasing herbage accumulation, also contributes to reducing the greenhouse effect, considering that the need for nitrogen fertilizers is decreased (Sollenberger & Dubeux Junior 2022). This has potential to lower emission of nitrous oxide (N 2 O), a potent greenhouse gas (Aranha et al 2018, Rusdy 2021, Robertson et al 2004, Simioni et al 2014.…”

Systems management strategies for increasing alfalfa use in warm‐humid regions

“…The adoption of legumes in forage systems in warm‐humid regions has historically been limited by (1) perceived lack of persistence, (2) lack of awareness of adapted varieties, (3) knowledge of management requirements (Shelton et al, 2005), and (4) coupling management with the growing conditions in the region (Silva et al, 2021). Integration of legumes in warm‐humid regions has many benefits including improved forage nutritive value in predominantly C 4 ‐grass regions of the world, reduced reliance on synthetic N fertilizer, and the potential for improved animal performance, ecosystem diversity, and economic returns (Muir et al, 2014; Sollenberger & Dubeux, 2022).…”