Peanut Response to Inoculation and Nitrogen Fertilizer

Experiments were conducted from 2000 through 2003 in North Carolina to compare peanut (Arachis hypogaea L.) response to inoculation with Bradyrhizobium. In one study that included 20 experiments, peanut pod yield was compared following no inoculation or inoculation with commercial granular or liquid infurrow products. In six of these experiments, inoculant was also applied to the seed before planting. In six other experiments within this study, pod yield of inoculated and noninoculated peanut was determined following surface applications of N approximately 40 d after planting. In a second study, peanut pod yield was compared in twin row planting patterns (two rows spaced 18 cm apart on 91-cm centers) when inoculant was applied in-furrow to one of the twin rows or to both of the twin rows. In a third study, interactions of in-furrow inoculation and fumigation with metam sodium were compared. Peanut pod yield was higher following inoculation in 7 of 20 experiments. In six of the seven experiments where a yield response to inoculation was observed, peanut had not been planted previously in these fields. In experiments where peanut responded positively to inoculant, pod yield was higher when inoculant was applied in the seed furrow rather than to seed before planting. Nitrogen increased pod yield linearly in three of six experiments (p <0.05). Inoculating both rows of peanut seeded in twin row patterns yielded higher in two of four experiments than when one of the twin rows was inoculated or when inoculant was not included. Fumigation with metam sodium did not affect pod yield, regardless of inoculation treatment.