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Soybeans and the Spring of 2018: One for the books

Seth Naeve, Extension soybean agronomist

Photo: Liz Stahl
Spring came late to all of Minnesota, but for farmers in Southern Minnesota, it came with too many May showers. This has made #Plant18 an especially tough one for farmers in the region. Many seasoned farmers have reported that this will be the latest start in their long memories.

It is natural to feel anxious and frustrated with the weather, but it’s important to know that fields will get planted and yields can still be quite good. For the most part, farmers should proceed as normal when windows of good weather allow.

Hold your current soybean varieties

An often-asked question revolves around moving to earlier soybean maturities as planting is delayed. Remember, that soybeans have an incredible ability to respond to short seasons by hastening maturity. A shortened seed-filling period is often offset for yield by a longer vegetative period that leads to larger plants. On the other hand, moving to too short of a soybean certainly leads to reduced yields due to a loss of potential yield accrual late in the season.

Therefore, we do not recommended moving to a shorter maturity soybean until June 10. However, there is a caveat: for producers who selected very long-season varieties for their area with the goal of getting an early start at planting, the switch to shorter lines may need to happen a little earlier.

Holding existing varieties will allow producers to utilize the full season to maximize soybean yields. Additionally, farmers should assume that they have chosen the absolute highest-yielding soybean genetics for their farm that is available. Switching soybean seed will inevitably result in a trade-down. A lower yield potential is a guarantee.

Yield potential is still high

Yield potentials are maximized in Minnesota when soybeans can be planted soon after May 1. However, significant reductions in yields are not noted until mid-May. By the last couple of weeks of May, yields are reduced by less than ½ bushel per acre per day. But by June 1, yield losses accelerate and potentials are reduced by more than ½ bushel per acre per day. It’s not too late to plant soybeans, but this is a good time to get it done.

So, what should producers do when they are under the pressure of the calendar and the weatherman? In general, producers should follow their same best management practices used when planting early. Good management practices in early May are the same as good management practices in late May.

However, with warmer soils and rain in the forecast, there are some things that some producers could take advantage of. Some fields may be too wet for tillage, but yet are dry enough on top to plant. These may be good candidates for direct planting. If field cultivating will delay you, consider directly planting before the next round of storms. Tractor speeds may be reduced, but planting slow may be better than not planting at all. With warm soils and rain in the forecast, seed can be planted shallow. Just be sure that all of the seed is being covered. Weed control can be more challenging with direct seeding, so appropriate preemergence herbicides should be used in a timely manner.

Good luck to all of those out there battling to beat the rains. Just remember, those beans will be popping out of the ground in a few days. Your efforts will soon be visible to all.
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