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Planting Soybeans Behind The 2011 Flood-A Followup

In late spring of 2011, flooding of a large acreage in the lower Mississippi River Valley floodplain left soybean producers with a dilemma–how to manage the late planting that would result from this event.

My blog article on June 8 2011 and an MSU Extension Service White Paper (MSU publication 2680) gave tips to help producers cope with this situation.

The one thing that was lacking in both of the above information pieces was actual data to support Maturity Group (MG)/variety selection decisions when growing soybeans in these late plantings.

Dr. Ernie Flint, Area Agronomist–MSU Extension Service, in cooperation with Mr. Brad Burgess,Operations Manager–MSU Variety Testing, and Mr. Philip Vandevere, County Director–Yazoo County Extension, decided to use the 2011 flood occurrence as an opportunity to evaluate the late-planting scenario that resulted. Mr. Bob Ragland, a soybean grower in the Satartia area of Yazoo County, was the cooperating producer.

Six varieties from each of the groupings of early and late MG’s IV and V were selected for planting that occurred on June 28 on a Sharkey clay loam soil. The study site had been inundated with flood water for approximately 6 weeks to a depth of 6 to 8 feet before planting. Row spacing was 18 in. Soil moisture was near optimum at planting, and seedlings were emerged five days after planting.

Results from this one-year study follow.

Results from post-flood soybean plantings made in Yazoo County, MS in 2011.
Variety Grouping Seed yield–bu/acre Mature height–in. No. of nodes
Avg. MG IV early 9.2 15 15
Best 2 MG IV early 11.5 15 15
Avg. MG IV late 12.2 16 15
Best 2 MG IV late 13.6 16 15
Avg. MG V early 18.1 17 13
Best 2 MG V early 20.8 17 12
Avg. MG V late 36.3 17 14
Best 2 MG V late 48.6 23 14


Conclusions from this study follow.

 


  • Mature height of varieties in the three earliest maturity groupings was less than 17 in., and this was too short to allow efficient harvest because of low pod set.

  • Number of nodes among varieties of the different maturity groupings was similar, which indicates that internodes of varieties in the earlier groupings were shorter than those of varieties in the late MG V grouping.

  • The later maturing varieties, in this case late MG V’s, yielded the most when planted late following flooding. In fact, the average yield of the best two varieties in this grouping was 48.6 bu/acre.

  • Variety selection within the late MG V grouping was important for these late plantings since yield of the best two of the six late MG V’s exceeded the average of the group by 12+ bu/acre.

  • The higher yields from the later varieties did not result from increased nodes, but were associated with taller plants of the better-adapted higher yielding varieties which enhanced harvest efficiency.

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Again, these are results from only one year; however, this type of research that usually cannot be replicated in time provides invaluable information for producers should these conditions reoccur in the future.

Caveat: Some plots in this study were reduced to marginal plant populations by damage from three cornered alfalfa hoppers. This stand reduction had a more pronounced effect on the earlier-maturing varieties (early and late MG IV's and early MG V's) because they were short and would not have compensated as well as the taller, later-maturing varieties (late MG V's). The LSD values relative to the mean of the test and the CV's in the three tests with the earliest varieties were very high. Thus, these results may not reflect the genetic potential of individual varieties. However, this was a "real" situation and does not detract from the take-home message of this study; i.e., varieties in the late MG V grouping produced the taller plants that resulted in greater harvest efficiency, and they produced a greater and very acceptable yield from these late plantings.

In my earlier blog cited above, I stated that “most available information leads to the selection of MG VI varieties for greatest yields when planting from mid-June through about mid-July since they have the potential for the longest fulfilled growing season”. According to the above results, this can be modified to include late MG V varieties when growing soybeans in these conditions.

The MSPB thanks the above-listed persons for going the extra mile in conducting these studies, and for quickly getting the results to producers. Details of the study are published in the 2011 Mississippi Soybean Variety Trials, p. 60-62.
Reviewed by Dr. Ernie Flint.
larryheatherly@bellsouth.net