Henry J Mascagni Jr., Louisiana State University AgCenter - Northeast Research Station, St. Joseph, LA
The cost of producing corn has increased dramatically over the last few years. Much of the increased costs have been associated with higher nitrogen (N) fertilizer and seed costs, which depends on factors such as yield potential, soil type, and hybrid. Fixed-ear type hybrids (determinate) may respond more to higher seeding rates than flex-ear hybrids (indeterminate). Optimum N rates may also be affected. Information is needed on the interaction among hybrid, seeding rate, and N fertilizer effects. Field experiments were conducted on Sharkey silty clay and Commerce silt loam at the Northeast Research Station near St. Joseph, LA to evaluate the influence of two hybrids, four seeding rates, and four N rates on yield performance. Targeted plant populations were 24,000, 28,000, 32,000, and 36,000 plants/acre and N rates ranged from the control to 350 lb N/acre at 50 lb increments. At both low and high yield potentials, yield increased as seeding rates increased for the fixed-ear hybrid. On the other hand, optimum population for the flex-ear hybrid was about 28,000 plants/acre at lower yield potentials but tended to increase with seeding rates as yield potentials increased. There was little evidence of interactions between N fertilizer rate and seeding rate and hybrid treatments for yield.