Nitrogen Contribution from Peanut Residues to Brassica Carinata.

Farmers in the US southeast are often recommended to reduce nitrogen (N) fertilization after peanut (Arachis hypogaea L.) by co-operative Extension services. However, these guidelines are not supported by the scientific literature. An experiment was conducted to quantify the N credit from peanut to a subsequent carinata (Brassica carinata) crop. A 3 (history: cotton (Gossypium hirsitum L.), peanut, fallow) x 5 (N rates: 0, 34, 67, 101 ,134) kg/ha factorial randomized complete block split-plot design with 3 replications (irrigated site) and 4 replications (non-irrigated site) was conducted in Jay, FL during 2019. Preliminary results indicate that N credits from peanut were not different from the fallow control but were significantly higher than previous cotton. Yield response was similar across irrigated and non-irrigated sites. NDVI during initial crop development responded similarly to yield responses; NDVI response was significantly lower after cotton compared to those after peanut and fallow. These preliminary results appear to support a growing body of literature that suggest minimal N credits to subsequent crops after peanut and may suggest a yield depression after cotton rather than a yield increase after peanut.

Keywords: Arachis hypogaea, nitrogen credit