• The trial consisted of two sets – North and South.
• Each set had three Iowa locations: 
  • North Set – Storm Lake, Marble Rock, and Huxley
  • South Set – Huxley, Atlantic, and Victor
• Each RM group consisted of three unique Channel® brand soybean products.
  • Three products were considered early RM for the location:  
    • North Set – 1.2 to 1.6 RM
    • South Set – 1.8 to 2.4 RM
  • Three products were considered normal RM for the location: 
    • North Set – 1.8 to 2.4 RM
    • South Set – 2.9 to 3.7 RM
  • The 1.8 to 2.4 RM group consisted of the same three products for both the North and South sets.
• The trial was a mix of plot sizes, replications (reps), and row spacings:
  • Storm Lake (4 reps)—six row strips, 20-inch spacing
  • Atlantic (2 reps) and Marble Rock (4 reps)—four row strips, 30-inch spacing
  • Huxley (3 reps)—six row strips, 30-inch spacing
  • Victor (2 reps)—eight row strips, 30-inch spacing
• During the growing season, all sites recorded 20+ inches of rainfall with Atlantic receiving 32 inches total. 
• The Marble Rock site received several heavy rainfall events. 

UNDERSTANDING THE RESULTS

• Delayed planting dates in the spring and late rains in the fall favored the normal RM group at the sites tested in 2019.
• The normal RM group had a 6.0 bu/acre advantage over the early RM group at the North and South locations (Figures 1 & 2).

KEY LEARNINGS

• In 2019, the early RM products yielded, on average, 6.0 bu/acre less than the normal RM products and yields ranged between 3 to 10 bu/acre less than normal RM products.
• In 2019, rainfall was plentiful with Marble Rock receiving the heaviest one-time event, and with Atlantic receiving over 32 inches total.
• The 2019 growing season favored the normal RM products, especially with a few delayed planting dates and excessive late-season rainfall that the normal RM group was able to utilize.
• More research needs to be conducted in the genetic pipeline to better understand which soybean products can be grown south of their main area of adaptability. 
• It should be noted that a RM shift may not be for every operation and that its benefits could be defined in terms other than yield.
  
  
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Yield Observations When Shifting To Earlier Maturity Group Soybean - 2018

• We continue to see a trend of growers planting earlier maturity group (MG) soybeans for the region and managing them at a higher level with seed treatments and foliar applications of fungicide and insecticide. This phenomenon, dubbed “MG shift”, is becoming increasingly important in some locations.
• There are many benefits of planting early MG soybeans including, but not limited to, earlier harvest timing, earlier cover crop seeding, and risk management benefits.
• The objective of this trial was to determine the yield impact of early MG soybean product selection against the normal MG products for the location.

• This trial was broken into two sets, North and South Iowa, with a total of eight locations – four locations in the north set and four locations in the south set:
  • North Set – Fonda, Storm Lake, Marble Rock North, and Marble Rock South
  • South Set – Huxley, Atlantic, Shenandoah, and Victor
• Each set consisted of 18 unique soybean products:
  • Nine products are considered early MG
    •  North Set – 1.1 MG to 1.8 MG
    •  South Set – 2.0 MG to 2.4 MG
  • Nine products are considered normal MG
    •  North Set 2.0 MG to 2.4 MG
    •  South Set – 2.9 MG to 3.5 MG
  • The nine 2.0 to 2.4 MG products were the same products for both the north and south sets
• The plots consisted of four, 15-ft-long rows in 30-in row spacing with three replications.
• The Shenandoah site exhibited above average levels of frogeye leaf spot and insect feeding.
• Above average levels of sudden death syndrome were observed at the Victor site.
• The Marble Rock North site was impacted with hail on August 28th.

• The effect of maturity group on soybean yield was variable and highly dependent on the location. For example, Victor saw an 8 bu/acre yield advantage with early MG products, whereas Huxley realized a 7 bu/acre advantage with normal MG products.
• In general, three locations (Atlantic, Victor, and Storm Late) saw some level of yield advantage with early MG soybean products versus the other locations where normal MG products gained some yield advantage. However, average site performance across all locations was nearly similar at 58 bu/acre.

• In general, early MG soybean products yield close to late MG products, especially when conditions are favorable.
• In this trial, there were some unfavorable growing conditions (listed below) in the locations where the normal MGs succeeded:
  • Excessive rain, wind, and hail
  • Weathered/delayed harvest
  • Lower management (no R3 growth stage fungicide/insecticide application)
• Finding the proper genetic package for a maturity group is still critical when considering planting early soybeans.