By Eric Anderson
Over the past several decades, farmers across the Midwest have been planting soybeans earlier with the goal of getting soybeans in ahead of corn to maximize yields of both crops. The Great Lakes region has witnessed an increase of 18 annual frost-free days from 1951 to 2024, which has helped with this goal. Michigan soybean growers are currently planting almost half of the total area under soybean by mid-May, compared to early June in the 1980s.
Numerous university research trials have shown consistent yield increases when planting soybeans relatively early in a given region. Research in Michigan from 2018–2019 by Siler and Singh (2023) with five seeding rates and four planting dates with and without seed treatment found the maximum yield was achieved at the late April planting time with a final plant stand of 98,000 plants per acre. On-farm trials conducted from 2019–2023 at 25 locations in Michigan found a 1.5 bu/ac advantage on average of planting 2–3 weeks earlier than normal. A University of Nebraska-Lincoln study investigated the impact of planting dates (Apr 30, May 16, Jun 1, Jun 17) on yield and the length of time to reach various vegetative and reproductive stages. Though later planting in warmer soils decreased the time to V1 by two weeks, it did not allow the crop to catch up and delayed time to seed dry-down by about the same amount. They found planting early was critical to maximizing yield.
However, early planting is not without risk. Concerns when planting early include postemergence frost, compaction and sidewall smearing if soils are too wet, and longer time to emergence with higher risk associated with insect, pathogen and nematode damage.
Source : msu.edu