Nitrogen Strategy and Seeding Rate Affect Rice Lodging, Yield, and Economic Returns in the Midsouthern United States

Abstract

Seeding rate and N application strategies have been extensively researched for drill‐seeded, delayed flood rice (Oryza sativa L.) production in the midsouthern United States. However, little economic analysis has been performed to determine the effects of seeding rate and N fertilization strategies on high‐yielding, lodging susceptible rice cultivars. The purpose of this research was to determine the effect of multiple N fertilization strategies and seeding rates on rice lodging and grain yield and use the data to determine optimal rice management practices based on evaluation of economic returns. Studies were established in Louisiana and Mississippi during the 2010 and 2012 growing seasons. Rice was drilled at seeding rates of 161, 323, and 483 seeds m−2. Rice was fertilized with N at multiple rates and timings, representing recommended strategies as well as strategies designed to reduce lodging. Lodging and grain yield data were collected and used to determine net returns at high and low rice and N prices. Rice grain yield and net returns were maximized at a seeding rate of 323 seeds m−2. Splitting N application between early‐season (V3) and late‐season (R1 or R3) applications decreased lodging, but resulted in decreased grain yield compared to optimal rates of N applied at V3. The 202 kg N ha−1 applied early‐season (V3) N fertilization strategy maximized both grain yield and net returns, despite relatively high levels of lodging. Optimal N fertilization during early‐vegetative growth appears to be necessary to maximize yield potential in this rice production system.Core Ideas Split N application in rice limits lodging but also reduce grain yield. High N rates and seeding rates increase lodging and harvest costs. Appropriate early‐season (preflood) N is necessary to maximize rice grain yield.