BROOKINGS, S.D. - One management strategy soybean growers can implement to reduce risk associated with Mother Nature is to grow soybeans with varying maturity ratings.
"With this approach, producers are not 'putting all their eggs in the same basket' so to speak," said David Karki, SDSU Extension Agronomy Field Specialist.
He further explained that planting soybeans other than recommended maturity group for the region, especially early maturing varieties, allows producers to start harvest earlier in the fall and continue field activities such as establishing cover crops and/or timely winter wheat planting.
"Throughout recent growing seasons, growers have commented that early soybeans have performed equally well in terms of yield, if not better, than soybeans with recommended maturity ratings," Karki said.
What SDSU Extension Research Has to Say
In collaboration with interested growers and the South Dakota Agricultural Experiment Station at SDSU, SDSU Extension established a small plot trial during the 2017 growing season at two locations in Northeast South Dakota.
The first location was at the SDSU Northeast Research Station near South Shore. The second was in a Clark County soybean grower's field near the town of Henry.
The trial used two early varieties (rated 0.2 and 0.3) and two recommended varieties (rated 0.9 and 1.0) provided by Mycogen Seeds.
All varieties were planted at two different dates:
- May 5, 2017 which was early
- May 23, 2017 which is when soybeans are typically planted in the area.
The test plots were 10-feet-by-40-feet plots with four replications for each planting date.
Due to consistent rainfall in the second half of September harvesting was delayed more than normal and was only completed October 3, 2017.
The results featured in Table 1 show that yields, even though numerically quite different, were not statistically significant at the Henry location, especially for the early planting date.
"This could be due to weed pressure and population loss as a result of heavy rainfall in late June," said Anthony Bly, SDSU Extension Soils Field Specialist.
He explained that this site received 9-inches of rain in three days the last week of June, which flooded almost half of the early planted plots.
Some early flooded plot yields were not as consistent at harvest compared to the non-flooded plots.
Therefore, the yields from flooded plots were not used while running statistics which may have contributed to large Least Significant Difference (Table 1). This resulted in difficulty to statistically distinguish mean yields for the maturity ratings used in the study.
At the Northeast Research Station, yields from the earliest maturing soybean variety (i.e. 0.2) were significantly different from the other three soybean varieties for both plating dates.
"These results suggest that planting soybean varieties that are earlier than half the maturity point than recommended for the region did not result in equal or higher yields in 2017 growing season," Karki said.
This research group plans to continue this study in the 2018 growing season. The study was funded by South Dakota Soybean Research and Promotion Council.