Northwest and Allee Research and Demonstration Farm
Producers continue to plant corn at higher plant populations each year with the introduction of more stress-tolerant hybrids. As row width stays the same, plants are growing closer together, which leads to more competition among plants. Planting corn in narrower rows allows more equidistant spacing of plants and less competition. Switching to narrow rows (15 or 20 in. rows) requires additional equipment to spray and harvest. Planting corn in twin rows that are spaced eight inches apart and centered on 30-in. rows is one system that allows more equidistant spacing and would not require changes in spraying or harvesting equipment. A study comparing twin rows to single 30-in. rows at various populations was conducted in 2010 at the Northwest Research Farm.
Iowa State University
Rusk, Ryan and Sievers, Joshua L., "Comparison of Twin Row and 30-in. Row Corn" (2011). Iowa State Research Farm Progress Reports. 268.