Update:
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Why the research is important to ND soybean farmers:
The goal of this project is to continue building NDSU databases on soybean yield impact with three trials examining specific plant nutrition and establishment factors:
PLANT NUTRITION
1. Double-inoculated soybean seed: With recent soybean production history, is there a yield response with using two rhizobia inoculant formulations (granular plus liquid as a ‘double inoculant’) vs. single formulation or no inoculant?
2. Special fertilizer inputs: Is there a yield response to soil- or foliar-applied sulfur (S)?
PLANT ESTABLISHMENT
3. Rye as a cover crop: Will winter (cereal) rye as a cover crop impact soybean yield while providing soil benefits compared to conventional soybean production?
Research:
• Trial 1: Conducted at NDSU Carrington Research Extension Center and Tri-county research site near Wishek during 2015-18 (6 site-years) with granular, liquid, and the combination of rhizobia inoculant formulations applied to soybean seed on ground with prior soybean production history.
• Trial 2: Conducted at Tri-county research site during 2016-18 using preplant, soil-applied S as MES15 (Mosaic) or foliar-applied as MAX-IN S (Winfield).
• Trial 3: Commenced in 2018 at the Tri-county research site with the following treatments: 1) soybean grown without rye as a cover crop; 2) rye terminated with glyphosate one month before soybean planting; and 3) rye terminated with glyphosate at soybean planting.
Findings of the research:
• Trial 1: Seed yield was statistically similar among treatments.
• Trial 2: No seed yield response with soil- or foliar-applied S compared to the untreated check during each year of the trial. The trial continues in 2019.
• Trial 3: Research continues in 2019 and requires multiple years of data before reaching conclusions.
Benefits/Recommendations to ND soybean farmers and industry:
• Trial 1: With a previous history of soybean (1 to 3 years separating soybean crops), single or double inoculation of soybean seed with rhizobia will not increase seed yield.
• Trial 2: Current results of this research indicate a lack of soybean yield response with S.
• Trial 3: Use of winter rye before soybean production provides numerous potential benefits including reduction in soil erosion, weed suppression and long-term improvement in soil productivity. Timing of rye termination with glyphosate needs to be carefully considered to balance the benefits of the cover crop while preserving soil moisture for the soybean crop.