Strategies for Increasing Rhizoma Peanut Contribution to Productivity and Ecosystem Services of Low-Input Pasture Systems

View the project final report

• 2011 annual report
• 2012 annual report

Commodities

• Agronomic: grass (misc. perennial), hay, rye
• Animals: bovine

Practices

• Animal Production: feed/forage, grazing management, grazing - rotational, pasture renovation, pasture fertility, winter forage
• Crop Production: cover crops, nutrient cycling
• Farm Business Management: feasibility study, whole farm planning
• Natural Resources/Environment: carbon sequestration
• Soil Management: nutrient mineralization, organic matter, soil quality/health
• Sustainable Communities: sustainability measures

Three experiments were established to evaluate incorporating rhizoma peanut (RP) into low-input pasture systems in Florida. An establishment study illustrated that Florigraze and Ecoturf RP have the greatest potential for incorporation into strip-planted bahiagrass systems. Evaluation of new RP genotypes indicates that while total herbage accumulation was not affected by grazing management in Year 1, changes in above and below-ground sward characteristics suggest that RP genotypes may favor a 6- vs. a 3-wk regrowth interval. In the forage systems study, the greater productivity of bermudagrass compared with RP and use of grazing vs. hay harvest increased plant litter pools and the potential for C and N contribution.

Introduction

   The purpose of this project is to develop strategies that facilitate legume incorporation into grass-based livestock production systems in the USA Gulf Coast Region and to quantify the effect of this practice on soil quality. This technology is needed because current production systems are based on nitrogen (N)-fertilized grasses and are increasingly vulnerable to high fertilizer cost.

   In the USA Gulf Coast Region, warm-season perennial grasses such as bahiagrass (Paspalum notatum Flügge) and bermudagrass [Cynodon dactylon (L.) Pers.] form the basis for grazing systems (Ball et al., 2007). Fluctuating costs of inputs to these systems, especially fuel and fertilizer, have made incorporation of legumes increasingly necessary for pasture-based livestock production. Legumes are high in nutritive value and fix N₂, decreasing the need for commercial N fertilizer, an input that has become too expensive for some producers. Rhizoma peanut (RP; Arachis glabrata Benth.) is a warm-season perennial legume that is well adapted to the region and has potential for incorporation into grazing systems. Unlike most warm-climate legumes, RP has well-documented persistence and ability to spread in grass pastures (Ortega-S. et al., 1992). Some existing pastures have persisted for 30 years (L.E. Sollenberger, personal communication, 2011).

   High cost of establishment of pure stands of RP (~ $550/acre) has made it uneconomical for use in livestock enterprises with relatively low return, e.g., beef cow-calf systems, and limited its use primarily to a high value hay crop for horses or dairy cattle. Lower-cost, alternative establishment strategies are needed if RP is to make significant contributions to grazing systems for livestock. One approach for lower-cost incorporation of RP into grass pastures is strip-planting. Because RP is a long-lived perennial with ability to move laterally via an extensive rhizome system, it has potential to spread into the surrounding grass areas over time and form a mixed pasture. Recently-released cultivars of RP range in growth habit from decumbent to upright, and these differences likely will affect their ability to spread in grass pastures (Quesenberry et al., 2010). Plants with varying growth habits also will likely respond differently to a range of grazing management strategies. No research has evaluated responses of RP cultivars with varying growth habits to strip-planting or to grazing management. The success of the strip-planting approach is dependent upon selecting RP cultivars that spread vigorously in grass pastures and tolerate grazing. The proposed research is designed to identify these cultivars.

   Finally, increasing emphasis is being placed on the ability of grasslands to provide ecosystem services, and conversion to RP-based systems has potential to contribute significantly (French et al., 2006). Tropical and temperate grasslands play a major role in the global C cycle and serve as an important C sink. Management of grass-based forage systems, e.g., N fertilization, haying vs. grazing, and grazing at a range of stocking rates, affects their potential to store C (Franzluebbers and Stuedemann, 2009), but little attention has been given to perennial legume-based pasture systems. This information is needed, and the proposed research will be an important step toward providing it.

1. To quantify the effects of growth habit of rhizoma peanut (RP) and defoliation management during the establishment year on ground cover and rate of spread of RP cultivars following strip planting into bahiagrass pasture
2. To measure the effect of grazing intensity and frequency on forage accumulation, persistence, and nutritive value of four RP cultivars differing in plant growth habit
3. To quantify the effect on soil organic carbon and nitrogen accumulation of forage systems based on RP or nitrogen-fertilized bermudagrass