A Practical First Look at Corn Production with High Plant Populations and Higher Nitrogen Rates in Single-Row and Twin-Row Systems.

Research in the Mississippi Delta has shown a significant increase in grain yields as seeding rates reached 40,000 plants/acre in a 40-in row bedded production system utilizing a twin-row (TR) planting system. Narrower rows have been used throughout other regions of the country where beds have not been required for drainage and furrow irrigation. While the initial research to evaluate nitrogen (N) rates and seeding rates in TR, no yield plateau was established with increasing seeding rates. A multi-year study was established at Stoneville, MS to evaluate seeding rates of 25K, 35K, 45K, 55K and 65K in both single-row (SR) and TR planting systems. Three N rates were selected (240, 280, and 320 lb N/acre) for evaluation with 120 lb N/acre applied a planting, and the remainder as sidedress applications. The last 40 lb N/acre was applied as a simulated aerial application of urea at or near tassel emergence. All cultural practices were held constant through out the growing season. Grain yields were calculated by harvesting the center two rows of each 4-row plot with a sample collected to determine harvest moisture, bushel test weight and Seed Index (100-seed weight). Total ears were collected on a 10-ft section of non-harvest row (Reps 1-3) or 20-ear samples (Reps 4-6) to determine ear number and ear size. In general, as plant population increases, ear size decreases and as competition arises, barren stalks are evident. Grain yields ranged from 209.2 bu/acre for SR-25K @ 240 N to 253.5 for SR-55K @ 240 or 280 lb N/acre. The initial analysis of variance for yield showed a significant seeding rate by rows configuration interaction and no significant response to increasing N rates. Seed Index was decreased significantly as seeding rate increased. The other analysis is yet to be completed.