As we are paused mid-way through spring planting season in Iowa, farmers and agronomists are closely monitoring weather conditions that will impact planting of the corn and soybean crop. This year’s planting season has some resemblance to spring 2024, with a decent planting window in early to mid-April followed by late April rain and cool temperatures. Despite these challenges, high yield potential is not lost.
In Iowa, the planting season started promisingly with favorable conditions in early to mid-April. USDA NASS estimated 34% of the corn crop was planted and 25% of the soybean crop. This is ahead of last year and the 5-year average. While there is some skepticism of accuracy of these planting estimates, I suspect there is more corn and soybean planted than these estimates.
Even so, planting is currently paused due to weather delays in most of Iowa, there is some concern with lost yield potential due to delayed planting. Both soybean and corn yields remain at very high yield potential through May 15-20 (Figure 1). Believe it or not, this has been consistent for three decades. Note that soybean yield potential is maintained at a higher level than corn beyond May 20. For this reason, it is extremely important to get corn planted ahead of soybean if we are anticipating further weather delays.
Data from Iowa State University’s Northern and Northeast Research and Demonstration Farms at Kanawha and Nashua further put pause to fear of lost yield potential (Tables 1 and 2). In 2024, at both locations, May planted corn had equal to higher yield than April planted corn. Soybean yield was statistically the same for April and mid-May planting dates at Kanawha while all soybean planting dates at Nashua had similar yield.
Despite this seemingly long pause to planting for some, it is still possible to achieve high yield potential with early to mid-May planting dates. As we navigate through the spring season, it's crucial to stay optimistic and proactive in our approach to planting.
| Date Planted | Corn Yield (bu/ac) | Soybean Yield (bu/ac) |
|---|---|---|
| 21-Mar | 198.5 b | 60.3 b |
| 11-Apr | 233.3 a | 76.9 a |
| 14-May | 250.4 a | 68.6 ab |
| 30-May | 257.1 a | 63.7 b |
| p<0.0001 | p=0.0013 |
| Date Planted | Corn Yield (bu/ac) | Soybean Yield (bu/ac) |
|---|---|---|
| 20-Mar | 197.5 c | 63.0 |
| 11-Apr | 225.2 b | 61.3 |
| 6-May | 248.7 a | 63.4 |
| 18-May | 249.9 a | 64.6 |
| 2-Jun | 224.0 b | 61.6 |
| p<0.0001 | p=0.7666 |
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- Associate Professor
- Extension Cropping Systems Specialist