Interseeding crabgrass and berseem clover into sorghum-sudangrass for improved herbage accumulation, nutritive value, and weed suppression

Authors: Burt, Justin; Soder, Kathy; Mercier, Kelly

Submitted to: Crop, Forage & Turfgrass Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sorghum-sudangrass is a common warm-season annual forage used throughout the world for grazing. However, weeds can be an issue with this crop. There is growing interest in reducing weed competition by interseeding annual forages such as crabgrass and/or berseem clover into the sorghum-sudangrass stand. Results of this study found that including crabgrass into the sorghum-sudangrass stand reduced weed competition, while not negatively impacting forage yield or quality, despite having different row spacings and establishment methods. Future research is needed to evaluate other compatible forages and contrasting harvest methods to determine their impact in grazing or stored forage production.

Technical Abstract: Sorghum-sudangrass hybrids (Sorghum. bicolor × Sorghum. bicolor var. sudanense; SSG) are common warm-season annual forages utilized in forage systems in the northeastern US. However, weed control can be an issue, particularly in low-input forage systems. Interseeding annual forages, such as crabgrass (Digitaria sanguinalis L.; CG) and berseem clover (Trifolium alexandrinum L.; BC), is of interest to aid in weed control due to their rapid growth and desirable nutritive value. A two-year small plot evaluation was conducted to determine the agronomic benefits of interseeding CG and BC via non-till drill or broadcast seeding into SSG established on different row spacings. Total herbage accumulation (HA) did not differ by year for any of the treatments evaluated (p > 0.13), despite having different row spacing and companion crop establishment methods. Botanical composition of these mixtures varied among treatments (p < 0.01) for all components. Treatments containing CG had lower HA of SSG, BC, and ‘other’ undesirable species. Crude protein did not differ (p = 0.55) across treatments; however, treatments containing high amounts of crabgrass had the lowest (p = 0.03) total digestible nutrients. This study concluded that while row spacing and the interseeding of annual forage species does not impact the overall HA of SSG, they do affect the botanical composition and nutritive value of the stand. Future research is warranted evaluating other compatible forages and contrasting defoliation methods to determine their impact the agronomic production of these types of mixtures, such as grazing or stored forage production.