Understanding the agronomic and economic impact of contrasting harvest strategies in two alfalfa–bermudagrass mixtures in Southeastern United States

Abstract

Background

Alfalfa (Medicago sativa L.) and bermudagrass (Cynodon spp.) mixtures (ABG) can be effectively managed in Southeastern United States under cut and graze management systems. However, there is still a need to investigate the influence that bermudagrass cultivar has under these harvest management strategies (HMS) grown in this mixture.

Methods

A 2-year trial evaluated bermudagrass cultivars (“Russell” or “Tifton 85”) interseeded with alfalfa (“Bulldog 805”) under three contrasting HMS (cut only [CO], graze only [GO], or cut and graze [GC]) in Tifton, Georgia, USA. All data were analyzed for animal performance, forage, and total system performance using the PROC MIXED procedure in SAS. An economic benefit–costs analysis was performed to compare the returns to each HMS on a per-hectare and a per-head basis.

Results

Bermudagrass cultivar and HMS did not interact in any parameters evaluated (p > 0.35). Overall, HMS affected the responses more than bermudagrass cultivar. Forage and animal productivity were generally greater during the in-season grazing period compared to the deferred grazing period. Cutting management maximized total system performance (p < 0.01). Economic analysis of computer simulated feeding outcomes indicated a net return of $2831 and $1295 ha⁻¹ yr⁻¹ for CO and GC systems, respectively, compared to an actually achieved return of $209 ha⁻¹ yr⁻¹ for the GO system.

Conclusions

Based on computer-simulated feeding results, addition of cutting management to the forage system, whether CO or in addition to grazing, provided better agronomic and economic returns compared to only grazing ABG mixtures. Future research should test the feasibility of the computer-simulated results and evaluate how ecosystem services are impacted when utilizing these HMS in other ABG mixture combinations.