Nutritive value responses of rhizoma peanut to nitrogen and harvest frequency

Abstract

Management strategies to enhance or preserve nutritive value of rhizoma peanut (Arachis glabrata Benth.) would be beneficial because high plant growth rates and adverse weather at harvest often result in low nutritive value for both pastures and hay along the coastal plain of the lower Gulf Coast. The objective of this study was to determine if a 30- or 60-d harvest frequency or 0, 110, or 220 kg N ha-1 fertilization could be managed to enhance crude protein (CP) yield and nutritive value of rhizoma peanut at three locations in Louisiana. Crude protein, neutral-detergent fiber (NDF), in vitro true digestibility (IVTD), and digestible NDF (DNDF) were measured on 'Florigraze' rhizoma peanut grown at three Louisiana locations in 1997 and 1998. Nitrogen fertilization increased CP yield approximately 80 kg ha-1 for the 110 and 220 kg N ha-1 treatments at two locations in 1 of 2 yr. Nitrogen fertilization affected nutritive value at two harvests at two locations in 1998 only. However, nutritive value was consistently lower for 60-d harvests than for 30-d harvests and was more consistent. Rhizoma peanut harvested in 1997 at 30-d intervals had 50 g kg-1 greater CP, 72 g kg-1 greater IVTD, and 40 g kg-1 greater DNDF coupled with 80 g kg-1 lower NDF than rhizoma peanut harvested at 60-d intervals. Likewise, there were seasonal influences on nutritive value. Responses in CP yield and nutritive value observed in this study were influenced more by environment (primarily rainfall) than by N fertilization and harvest management.