Implications of experimental design on predicting economic optimum nitrogen rates in rice.

Authors: ATWILL, R.L. - Mississippi State University; KRUTZ, L.J. - Mississippi State University; SPENCER, G.D. - Mississippi State University; BOND, J.A. - Mississippi State University; REDDY, K.R. - Mississippi State University; GORE, J. - Mississippi State University; WALKER, T.W. - Horizon Ag-Products, Lp; BOYKINS, D. - US Department Of Agriculture (USDA)

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2021
Publication Date: 11/12/2021
Citation: Krutz, L., Spencer, G., Bond, J., Gore, J., Reddy, K., Walker, T., Boykin, D. 2021. Implications of experimental design on predicting economic optimum nitrogen rates in rice.. Agronomy. 11:2296. https://doi.org/10.3390/agronomy11112296.
DOI: https://doi.org/10.3390/agronomy11112296

Interpretive Summary: Rice is the primary staple for over half of the global population and cultivated on approximately 160 million hectares worldwide. Nearly 90% of rice is grown in Asia, while less than 2% is produced in the US. In Mississippi, rice is the fourth largest crop by area and 500,000 metric tons are produced annually. Historically, nitrogen (N) fertilizer recommendations for rice have been defined according to the current inbred or hybrid cultivars being grown and are modified according to soil texture, tillage system, seedbed condition, and previous crop. Ihis study was conducted to determine if experimental design alters the predicted economically optimum N rates (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.

Technical Abstract: 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.