Corn Row Spacing Study at Dixon Springs

by S. A. Ebelhar

• Introduction

• Procedures
• Results
• Summary
• Table 1
• Table 2
• Table 3

Introduction:

Much has been written in the farm press touting the increased yields in central and northern Illinois associated with corn row spacings of 15-20 inches over the more conventional 30 inch-rows. We originally looked at 15 vs. 30 inch rows in 1993-94, and we revisited this topic in 1997-98. The objective of this work was to evaluate the effects of 15 vs. 30 inch row spacings, two hybrids, and two planting rates on grain yields of no-till corn grown in southern Illinois.

Procedures:

Two corn hybrids (Pioneer 3313 and 3231 in 1997, and Pioneer 33Y09 and 3231 in 1998) were planted at seeding rates of 26,000 and 32,000 seeds/acre in both 15- and 30-inch rows. Stands were thinned to final stands of 19,200 and 23,500 in 1997, and thinned to 20,900 and 25,300 in 1998 for the 26,000 and 32,000 seeding rates, respectively.

Results:

There was a 18 bu/acre yield increase with the 30" row spacing over the 15" row spacing with the Pioneer 3313 hybrid in 1997 and a 26 bu/acre increase with the Pioneer 3231 (Table 1). In 1998, there was no difference between row spacings for either variety, indicating that there was no advantage to the 15" rows. Over the two years and two varieties/year studied, there was a 13 bu/acre advantage for 30" row spacings over 15" row spacings. Seeding rate and final plant stands had no effect on row spacing response (Table 2). There were no interactions between row spacings, planting rates and hybrids.

How did our 1997-1998 results compare to 1993-94? In 1993 and 1994 we compared two corn hybrids at four planting rates each for 30" and 15" row spacings. Overall, there was a 19 bu/acre yield advantage for 30" row spacings over 15" row spacings (Table 3) which is very similar to the results in 1997-98.

We speculate that compaction over or closer to the corn rows with 15" row spacings compared to 30" row spacings would reduce yields more so on low organic matter soils in southern Illinois than on higher soil organic matter soils in central and northern Illinois. This would explain the lower yields under the 15" row spacings.

Summary:

• Corn grain yields with 30" row spacings were equal or significantly higher than 15" row spacings.
• Responses were unaffected by planting rates and hybrids.
• Yield responses were very similar to results we found in 1993-94.

Table 1. Row spacing by variety effects on corn yields at Dixon Springs, 1997-98.

Means within a column followed by the same letter are not significantly different at the 5% level.

Table 2. Row spacing by plant population effects on corn yields at Dixon Springs, 1997-98.

Table 3. Row spacing by variety effects on corn yields at Dixon Springs, 1993-94 (averaged over four planting rates).

Means within a column followed by the same letter are not significantly different at the 5% level.