Long-term productivity of rhizoma peanut and alfalfa in central Georgia

Rhizoma peanut (Arachis glabrata Benth.) has potential as a high-quality summer legume for the Coastal Plain region of the southeastern United States (US), but the limits of its productive life in this region have not been defined. A long-term field study was initiated in 1991 to compare yearly dry matter (DM) yield of rhizoma peanut with that of alfalfa (Medicago sativa L.) in Central Georgia. Yield data for the establishment period of 19921994 were published previously, and data from 1995 through 1999 are reported here. In 1999, seasonal growth and distribution of rhizoma peanut roots in the soil profile were also determined. Yield of rhizoma peanut ranged from 3793 to 9083 lb/acre during the five years of the study, with production differences due to available moisture. Alfalfa yields were 4760 and 4345 lb/acre in 1995 and 1996, respectively, after which the stand died out. Rhizoma peanut roots were well-distributed to 23 in soil depth. Total number of roots increased over the growing season, with most of the increase coming from deeper roots (7-23 in). Rhizoma peanut has excellent potential as a long-lived summer legume for the lower South.