Most crop farmers have known that corn has a specific time for planting to realize maximum yield. Farmers are also beginning to realize that soybeans also benefit from being planted at the right time to maximize yields. Recent research by Michigan State University Extension was done in Michigan’s Thumb to evaluate the effect of soybean planting date in relation to the planting population to determine optimum yield and income. The research was sponsored by the Michigan Soybean Promotion Committee and is the second year of this study.

In 2012, three planting date treatments spaced 10 to 14 days apart were established in the same field at Mossner Farms, Inc. near Richville, Mich. Each of the planting date treatments had four replications planted at populations of 80,000; 120,000; 160,000; 200,000; and 240,000 seeds per acre. Yields for each replication were an average of all planted populations.

Delays in planting can decrease soybean yieldsThe plans were to plant the soybeans in late April, mid-May and early June, but the intervals were compressed due to wet weather in late April that delayed the plantings. The dates for planting were May 11 (early), May 21 (mid), and June 7 (late).

Total yield was reduced at both the mid and late-season plantings by 3.9 and 14.6 percent, respectively. This resulted in a loss in income per acre of up to $147.90. The planting dates and yield data was very consistent with results from 2011. Table 1 highlights the results from each growing season.

The clear take-home message is that later soybean plantings will normally result in both reduced yield and income.

This plot was included in the TARE Thumb Ag Research & Education 2012 Field Trials and the SMaRT 2012 Research Report.