Yield and crop value expectations (current commodity prices) based on this study will provide producers, insurance agents and the RMA with important information on late planting seasons or replant situations that could include soybeans or cropping alternatives if allowed.

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Executive Summary
Seeding Date and Cultivar Influence on Soybean Performance in Northeastern North Dakota -2020
Principle Investigator: Bryan Hanson, NDSU Langdon Research Extension Center

Northeast North Dakota has seen a dramatic increase in soybean acreage in recent years especially counties along the Canadian border where the state’s coolest temperatures and shortest growing seasons occur. Choosing the right combination of seeding date and cultivar maturity group (MG) is an important decision producers make in obtaining optimum soybean production.

The objective of this study was to provide research based data to assist farmers in determining the relationship between seeding date and MG for the NE region of the state.

Research was conducted at Langdon, ND with five seeding dates and three MGs at each seeding date. Seeding dates were in approximate 10-day intervals ranging from May 21 to June 19. Maturity groups consisted of 00.5, 00.9 and 0.1 Roundup Ready cultivars. The target plant population was 180,000 plants per acre seeded in 6-inch rows.

Agronomic trait data trends indicated the number of days to mature decreased with later seeding dates while later MGs took more days to mature. Percent grain protein increased and oil content decreased with subsequent seeding dates with differences among varieties less than 0.5 percent at the two latest seeding dates.

Yield of cultivars were similar at the May 21 seeding date. On subsequent seeding dates, the 00.5 cultivar always had the highest yield followed by the 00.9 and 0.1 cultivars. Yield averages of the three cultivars at the five seeding dates were 62.7, 56.7, 43.6, 38.6 and 30.6 bu/a, respectively. The dramatic yield drop at the June 5, 12 and 19 probably resulted from the September 8 frost/freeze and the dry soil conditions in later August and September. Combined data from 2018 and 2020 resulted in yield reduction of 30, 36, and 43 percent from the earlies to latest seeding dates for the MG 00.5, 00.9, and 0.1. Cultivars seeded on June 25 did not mature prior to the first killing freeze on September 29 in 2018. The further seeding date is delayed into June, the greater chance of a successful crop with the earliest MG. The success of seeding the last ten days of June would be problematic with even the earliest MG and would be dependent on weather conditions and timing of the first fall freeze in any given year.