More Planting Trials
Row spacing has been controversial ever since equipment and crops no longer had to accommodate the width of a draft animal. Dave and Lisa Lubben, Monticello, normally drill soybeans and row-plant corn. In 1997 they compared drilled soybeans to soybeans they planted in 18-inch rows by making a second pass with the 36-inch-row planter. Not counting the expense of the second planter pass, the chief cost difference was due to the higher seeding rate for drilled soybeans (Table 12). Since there was no significant yield difference between the seeding methods, the greater cost of drilled soybeans tipped the balance in favor of 18-inch rows. The cost of the second planter pass would largely erase that advantage, however.
At the other end of the state, the Neely-Kinyon Farm compared corn in 30-inch and 15-inch rows (Table 12). Late summer was very dry in this part of Iowa, and overall corn yields were half of normal. However, the 15-inch-row corn yielded better than corn in 30-inch rows by more than 11 bushels per acre. This result runs counter to most of the trials on row spacing conducted by ISU, and the very low yield environment may have played a role. If so, this trial helps to fill in a piece of a very large puzzle, as industry, producers, and university agronomists reexamine the issue of row spacing.
Think you’ve heard the last word on row spacing? How about twin rows? Some ridge-tillers and other producers who aren’t ready to narrow their rows are looking at pairing two rows six or seven inches apart, retaining the customary row spacing between pairs. In 1997, Paullina cooperators Colin and Carla Wilson and Dan and Lorna Wilson tried out the twin-row ridge planter constructed by their cousins (and former PFI cooperators) Doyle and Lowell Wilson, Primghar. Seed cost was a little greater for the twin-row configuration, but no difference in yield appeared (Table 12). Colin reported somewhat earlier canopy shading for the twin rows, although weeds were not a problem in either system. He also saw more leaning plants in the twin rows at harvest time, although the combine was able to harvest the crop satisfactorily. Colin and Dan don’t think they will try the twin rows again. Their cousins, however, believe they have seen a benefit on their own farms and will continue planting twin-row soybeans.