Evaluating Conversion of Exotic Grass Pastures to Native Warm-Season Grass: Profitability Analysis and Response of Wildlife and Imported Fire Ants

View the project final report

• 2012 annual report

Commodities

• Animals: bovine

Practices

• Animal Production: feed/forage, grazing management, range improvement
• Farm Business Management: budgets/cost and returns, new enterprise development
• Natural Resources/Environment: biodiversity, wildlife

We investigated the economic and wildlife implications of converting exotic forages to native warm-season grass (NWSG). In spite of unfavorable growing conditions due to drought, cattle grazing NWSG consistently outperformed conspecifics on exotic grass forages. Partial budget analysis indicated that NWSG pastures yielded up to 36% marginal rates of return despite establishment costs. Fire ant indices did not differ among treatments, though NWSG increased Dickcissel productivity (fledglings/ha) through greater nest site availability. These results suggest NWSG can benefit avian species such as Dickcissels while offering a competitive alternative to exotic forages, resulting in net benefits for both conservationists and producers.

Introduction

The purpose of this project was to evaluate the costs and returns of converting exotic grass pastures currently used in production (bermudagrass [Cynodon dactylon] and tall fescue [Schedonorus arudinaceus]) to native warm-season grass (NWSG) pasture and to characterize the response of wildlife and imported fire ants (Solenopsis spp.). Converting exotic grass pastures to NWSG has the potential to restore the natural functions of pastures by simultaneously providing excellent forage for cattle, nesting structure for birds, and excluding imported fire ants (IFA). For example, the structure of NWSG may be more amenable for livestock foraging and performance than exotic forages (Burns et al. 1984), and varieties of NWSG can be adapted to local growing conditions, tolerating poor soil conditions (Jung et al. 1988) and requiring few nutrient inputs (Brejda et al. 1995). Preliminary results of meat quality studies at Mississippi State University also indicate that meat from cattle grazed on NWSG has similar consumer acceptability; but better shelf life, higher protein, and lower fat content compared with meat from bermudagrass (M. W. Schilling, pers. comm.). In addition, the tall and clustered growth of bunchgrass provides both suitable nesting structure for grassland birds and interspaces for wildlife movement (Harper et al. 2007). Exotic grasses are ubiquitous throughout the Southern United States as pasture and forage for cattle (Barnes et al. 2013). However, these forages are highly unsuitable for wildlife such as Northern Bobwhite (Colinus virginianus) and grassland songbirds because they grow in dense mats and outcompete other native plant species (Hays et al. 2005). Thus, widespread establishment of exotic forages has likely contributed to declines in many grassland songbird populations (Sauer and Link 2011). Specifically, NWSG should be preferable over exotic forages for the Dickcissel (Spiza americana), a bird species that selects grasslands with tall and dense vegetation to establish territories and nest (Zimmerman 1971). Disturbance from heavy grazing may also maintain early successional structure and composition preferred by IFA (Tucker et al. 2010), an important agricultural pest (Flanders and Brees 2009). 

Incorporating NWSG in cattle production has potential to substantially improve sustainability and wildlife conservation on private lands throughout the Southeast. However, NWSG conversion incurs costs from establishment and loss of revenue while pastures are taken out of production for two years. The possibility of not recovering these losses due to establishment failure, variation in market conditions, or weather therefore presents substantial risks for producers. Despite potential economic and environmental benefits of NWSG, uncertainty regarding establishment and risk remains a significant barrier to incorporating these grasses in livestock operations (Taylor 2000, Doll and Jackson 2009). Information is also needed on the costs and benefits of NWSG conversion to assist in distributing cost-share incentives to producers (Claassen et al. 2008). I therefore evaluated costs and benefits of NWSG conversion using an operational, experimental grazing system, and measured the response of a breeding grassland birds and IFA.

• Literature Cited

1. Conduct a partial budget analysis by creating enterprise budgets for NWSG establishment and grazing exotic and NWSG pastures; 
2. Characterize response of Dickcissels (Spiza americana) to NWSG conversion by quantifying nest density, daily nest survival rates, and number of fledglings produced per nest among grazing systems. I will focus on Dickcissels because they are common in Mississippi, their populations are declining, and they are a suitable model organism for grassland avifauna in general because they are obligate grassland nesters; 
3. Quantify IFA response to NWSG conversion, and if necessary include any costs for eradication in enterprise budgets.
4. Use sensitivity analyses on costs and cattle weight gain parameters to identify effective targets for cost-share or subsidies to make NWSG conversion viable.