Moving Beyond 300 Bushel Corn in Mississippi - Increasing Seeding Rates and Nitrogen Rates in Different Planting Patterns.

On-farm research in 2005-2007 in the Mississippi Delta found increased corn grain yields with seeding rates increasing from 25,000 to 40,000 seed/acre on 38-in bedded rows in a twin-row (TR) Production system. Narrower rows (3- in or less) in the Midwest have been the norm for many years but have not worked well for bedded systems in the South. In the initial study, grain yield was increased with a 40-K seeding rate. In 2017, a multi-year field study was initiated at Stoneville, MS to evaluate seeding rates from 25K to 65K in both single-row (SR) and TR planting systems. Nitrogen (N) rates were also included at 240, 280, and 320 lb N/acre. The N was applied just after planting (120 lb N/acre), at the 3-4 lead stage (120 lb N/acre), at the 6-leaf stage (40 lb N/acre - treatment based), and at pre-tassel (PTN, 40 lb N/acre - treatment based). Most N was applied as UAN Solution (32% N) banded-applied to both sides of the row while the PTN rate was applied as a simulated aerial application of urea. Grain yields were determined by harvesting the center tow rows of a 4-row plot with a commercial combine. Samples were collected to determine harvest moisture, bushel test weight and seed index (100-seed weight). Ear samples were collected to evaluate barren stalks and ear size. In 2017, SR yields were higher than TR yields in general. Grain yield ranged from 208.9 to 253.5 bu/acre with little response to nitrogen. In 2018, grain yields were again good with TR yields significantly higher than TR yield. As expected, ear weight tended to decrease as plant population increased and barren stalks increased at the higher seeding rates. Increasing N rates did not significantly increase grain yield in either year.