Yield Observations When Shifting to Earlier Relative Maturity Soybeans - 2020
We continue to see a growing trend for soybean growers to plant “early” soybean products and manage them at a higher level with seed treatments and foliar applications of fungicide and insecticide. This phenomenon, dubbed “relative maturity (RM) shift” is becoming increasingly important in some locations.
There are many benefits of planting “early” soybeans including, but not limited to, earlier harvest timing, earlier cover crop seeding, and risk management benefits.
The objective of this study was to determine the yield impact of planting “early” RM soybean products compared to planting normal RM products for the location.
With earlier planting dates in 2020 and rainfall events in September, the effects of RM selection on average soybean yield pointed to a clear yield advantage for the normal RM group.
The North set normal RM group had a 7 bu/acre advantage over the early RM group (Figure 1) and the South set normal RM group had a 13 bu/acre advantage over the early RM group (Figure 2).
In 2020, early RM soybean products yielded, on average, 7 to 13 bu/acre less than normal RM soybean products and ranged between +4 to 21 bu/acre less than normal RM soybean products for both locations.
In 2020, late season rainfall was less than ideal. The lack of adequate rainfall in July and August quickly finished off the early RM group, while the early September rains helped the normal RM group maximize pod fill.
More research should be conducted in the genetic pipeline to better understand which soybean products can be grown south of their typical production area.
It should be noted that a RM shift may not be applicable for every operation and any potential benefits can be defined in terms other than yield.