Don’t Sweat Delayed Soybean Planting – Yet
If you farm in areas inundated by prolific May rainfall, you’re probably grinding your teeth and getting sweaty palms worrying about delayed soybean planting. Don’t worry. Well, until June, anyway.
Seth Naeve, University of Minnesota (U of M) Extension agronomist, and David Nicolai, U of M Extension educator, report that 28% of Minnesota’s soybean acres are waiting to be planted as of this week. That’s four days behind last year’s planting progress. Some of the central, eastern, and southeastern sections of the state have only reached about 50% planted.
So what should farmers with unplanted soybeans do?
Well, a couple rays of hope exist. The 10-day forecast is starting to open up. So, sunny days are in the near-term future.
Second, soybeans cope with delayed planting quite well. Yield penalties for late planting can be tolerable. According to a long-term planting date study by Bruce Potter and Steve Quirring at the U of M Southwest Research and Outreach Center in Lamberton, yield losses through May in Minnesota are relatively small. Soybeans planted before June 1 should produce about 90% of those planted by the first week of May, on average. Minnesota farmers who haven’t planted soybeans yet are probably losing about .33 bushel per day with delayed planting during late May.
The time to worry is when June 1 approaches. Yield losses of about one percentage point per day in early June then occur. This would culminate in a 50% to 60% yield when soybeans are delayed (or replanted) on July 1.
In Minnesota, soybean maturity choice does affect the yield loss across planting dates. Very full-maturity soybeans tend to have the greatest yield potential when planted early, but the rate of yield loss across time is greater.
By late May, one should not expect a long-season soybean to outperform a similar variety of shorter maturity. The advantage of the long-season variety appears to be primarily through exploitation of early planting windows.
When should you switch to a shorter maturity soybean?
In Minnesota, conventional recommendations have been to hold soybean maturities until June 10. This still holds for producers who grow soybeans that are well-adapted to their latitude. Producers who have been selecting very long-season soybeans to take advantage of early planting should consider moderating their maturity choice by late May. They may choose varieties that are typically adapted for their area if they are confident that they can get them in by June 10.
Remember, exchanging seed usually puts one at an additional disadvantage, as the original seed selected was a better overall variety with a higher yield potential and better adapted to the specific field.
One additional caveat – the yield penalties mentioned above are based on an average year. Due to the recent cold weather in states like Minnesota, the actual yield penalty this year will be smaller compared to an average year, since the overall yield potential is also lower.
Early-planted soybeans in 2017 have struggled and are developing slowly. Beans planted in late May this year might lag behind soybeans of years prior, but they may not lag far behind those planted on May 15 of this year.