The continuous rainy weather that we've been experiencing can take an emotional toll on a farmer. It's easy to feel a little helpless looking out at those soggy fields. The common response is to keep active and begin to make contingency plans. Some producers are beginning to get nervous about their variety choices and are calling on their seed dealers to inquire about sourcing earlier maturity soybeans.
While this is a very normal response to the situation, it's important to remember that soybean maturities need not be adjusted for some time. The standard University of Minnesota recommendations state that soybean maturities should not be adjusted until a target planting date of June 10 is reached. We will have MANY good working days before then.
There are two primary reasons why soybean maturities need not be adjusted for some time. First, the soybean's reproductive development is much less impacted by heat unit accumulation than corn. Shorter days help trigger flowering and maturation in soybean, so that even late planted - full maturity - soybeans tend to mature naturally, if only a day or two late. Second, early May growth and development in Minnesota soybeans tends to be very slow. Historically, soybeans planted in early May are only one or two leaves ahead of soybeans planted in late May due to the warm soil and air temperatures experienced by the later planted soybeans.
A secondary (but perhaps equally important) reason to delay maturity shifts relates to variety availability. One should assume that they have already chosen the highest-yielding varieties for their farms. Any swapping that occurs in the spring will result in producers accepting lesser varieties in trade. Hold with your current varieties (at least) until a late May planting becomes imminent.
Note: Current University recommendations for late- and re-planting are based on antiquated research trials. We know that farmers are planting much longer maturity soybeans today. We know that this change will impact when soybean maturity switches should occur. This is a research project that we hope to take on in coming years.
Seth Naeve, Extension Soybean Agronomist