Soil Water and Nutrient Use in Low-Input Rhizoma Peanut-Bahiagrass Mixes.

Bahiagrass is a warm-season, tropical perennial forage and turf grass, commonly used for recreational areas, medians and highway right of ways, in the southern U.S. Increased stresses from extreme weather (including droughts), more aggressive mowing practices, and disease pressures, along with declining soil fertility, is resulting in periodic, partial stand declines. Stand loss leaves sloped areas susceptible to water erosion and weed encroachment. Biological dinitrogen fixing (BNF) rhizoma peanut originates from the same South American region as bahiagrass. A blended rhizoma peanut-bahiagrass sward may provide a healthier and more resilient groundcover under low-input management. A field plot study was initiated to compare two rhizoma peanut cultivars, Ecoturf and experimental line Q6b, mixed with either of two bahiagrass cultivars, Argentine and experimental dwarf line, F9. Rhizoma peanut and bahiagrass were grown in monocultures or as peanut-grass mixtures at two Florida locations. Soil moisture, water infiltration, soil pore water N and P, soil and tissue N and P, and yields were measured in 2013 and 2014. Natural abundance N-15 was used to track legume N in mixed plantings in 2014. Mixed plantings produced as much and sometimes greater yield than the experimental dwarf bahiagrass in monoculture and they produced similar yields to Argentine bahiagrass monoculture. The Argentine-Q6b mixture used more water from deeper in the soil profile (76 cm) than other treatments. Using BNF perennial legumes in a perennial grass sward for highway right of ways is a promising sustainable practice.