A Wisconsin survey of twin row corn planting found that less is more.

A few growers in recent years in Jefferson County, Wisconsin, have made the conversion to growing corn in row spacing less than 30 in. In spring 2006, a farmer was identified that purchased a twin-row configured 24-row planter. This same farmer also had a 12-row, 30-in. standard planter. Tim Bender, University of Wisconsin Extension Crops and Soils Agent, approached the grower with an interest in an on-farm test to compare row spacing and plant population recommendations. The producer was interested in trying to identify the optimum planting population for the twin-row technology as compared to his standard practice with 30-in. rows. This on-farm testing could help improve the reliability of his crop management decisions. It was decided that a strip trial be planted with four different populations with the twin-row planter replicated three times, and compared to 30-in. rows at one population. The twin-row planter was operated at 33,000, 36,000, 39,000 and 42,000 kernels per acre, and the standard planter at 33,000.

Results
The lowest plant population had the highest yields for both of the planter configurations. The top yield was 228.38 bu./acre achieved by the twin-row configuration at 33,000, along with the second rank yield of 223.02 bu./acre achieved by the 30-in. rows at 33,000 plant population. The twin-row top yield resulted in additional revenue of $24.58/acre with $3/bu. corn price after adjusting to 15% moisture and drying charge of 3.5 cents per point of moisture. The planters were operated side by side for this strip plot with each having the middle six rows harvested to avoid any outside row influence. The producer is planning to repeat the study in 2007 but will add an additional lower population of 30,000 kernels/acre.

12 bu. Gain
A farmer in another Wisconsin county called Bender to discuss a method to modify his older model planter into twin-rows. This particular farmer had already experimented with creating twin-rows by double back planting. His replicated plot resulted in a 12-bu./acre gain over his standard width of 36-in. rows. The grower said, “with the yield advantage we saw in 2006, one can make a very nice planter payment across 1,000 acres of corn.”