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Cool Bean: Soybeans teach us about nodulation

Shawn P. Conley and Ophelia Tsai University of Wisconsin
May 14, 2026
6 hrs ago

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Shawn P. Conley and Ophelia Tsai University of Wisconsin

Soybean is unique among major grain crops because it can get much of its nitrogen from the atmosphere through biological nitrogen fixation. That happens through a partnership between soybean roots and rhizobia bacteria. When the relationship is working well, soybean plants form nodules on their roots. Those nodules convert atmospheric nitrogen into a form the plant can use.

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Table 1. Planting date and commercial variety is shown in 2025 at the designated locations across Wisconsin. University of Wisconsin

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Figure 1. Soybean-yield comparison is shown among the non-nodulating line, nodulating isoline and commercial variety in 2025 across 10 Wisconsin locations. Letters indicate Tukey grouping comparisons across locations within each soybean type at α = 0.05. University of Wisconsin

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Figure 2. Soybean seed-protein concentration is shown among the non-nodulating line, nodulating isoline and commercial control in 2025 across 10 Wisconsin locations. Letters indicate Tukey grouping comparisons across locations within each soybean type at α = 0.05. University of Wisconsin

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Figure 3. Soybean seed-oil concentration is shown among the non-nodulating line, nodulating isoline and commercial control in 2025 across 10 Wisconsin locations. Letters indicate Tukey grouping comparisons across locations within each soybean type at α = 0.05. University of Wisconsin

Shawn Conley is a soybean and small-grains agronomist with the University of Wisconsin-Department of Plant and Agroecosystem Sciences, and the UW-Division of Extension. Ophelia Tsai is a first-year doctoral student working on researching soybean biological nitrogen fixation dynamics in Shawn Conley’s Cool Bean research lab.