Influence of Rotation Sequence on the Optimum Corn and Soybean Plant Population

Abstract

Rotation sequence and plant population are important management considerations for maximum yield. Response of corn (Zea mays L.) and soybean [Glycine max L. (Merr.)] to changes in plant population, rotation sequences, and tillage system was evaluated for 3 yr. Corn was planted in 76‐cm rows and had a final plant population of 56300, 65800, and 75200 plants ha−1; soybean was planted in 19‐cm rows with a final plant population of 294200, 450400, and 518500 plants ha−1 using conventional tillage and no‐tillage systems. Both crops were compared in seven rotation sequences. For corn yield there were no interactions of plant population with tillage or rotation sequence. Averaged over years, tillage did not affect corn yield. Corn rotated annually with soybean and first‐year corn after 5 yr of consecutive soybean yielded 12% more than continuous grown corn. Corn yields increased 11% as plant population increased from 56300 to 75200 plants ha−1, regardless of tillage or rotation treatment. Averaged over years, no interactions of plant population with tillage or rotation sequence on soybean yield were found. Soybean yields were 8% higher in conventional tillage than in the no‐tillage systems. First‐year soybean after 5 yr of consecutive corn yielded 8% more compared with the other six rotation sequences. Plant population within the studied range did not affect soybean yield. It was concluded that neither corn–soybean cropping history nor tillage system were important for determining optimum plant population for corn or soybean.