Nitrogen (N) response studies in rice (Oryza sativa L.) are conducted to provide grower recommendations with economically optimum N rates (EONRs). This study was conducted to determine if experimental design alters the predicted EONR for rice. The effects of experimental design and soil texture on predicted EONR were investigated near Arcola, Greenville, Minter City, and Shaw, MS on soil textures ranging from sandy loam to clay. The response of rice grain yield to seven N fertilizer rates was fitted with a quadratic equation, and the quadratic trend was compared between the randomized complete block (RCB) and split-plot (SP) designs. No differences were detected between RCB and SP designs for rice grain yield response to N rate; therefore, either design, RCB or SP, would be appropriate for use in N response studies for rice.
