Results from Soybean Research Conducted in Mississippi
Results from two research projects conducted at Stoneville, Miss. [lat. 33°26'N] are reported in articles titled “Planting time and variety effects on biomass, harvest index, and yield of irrigated soybeans in mid-southern United States” by Pieralisi et al. [Study 1] and “Agronomic performance of soybean with varied planting dates, row configurations, and seeding rates on two different soil textures” by Kelly et al. [Study 2]. Major points about the conduct of this research and its results follow.
Study 1.
• Furrow-irrigated field studies were conducted in 2017 and 2018 on both silt loam and clay soils that are typically used for soybean production in the region.
• Eight MG 4 soybean varieties were planted at 135,000 seeds/acre in 40-in.-wide rows in late-April/mid-May [Early] and late May [Late].
• Soybean yield was significantly affected by variety [yields ranged from 45.2 to 63.7 bu/acre] but not by planting date in this study.
• The two highest yielding varieties [62.3 and 63.7 bu/acre] had the greatest harvest index [HI = weight of seed/total weight of aboveground biomass (stover + seed)].
• In this study, soybean varieties that produced the greatest yields produced lesser non-reproductive biomass and greater reproductive biomass, which translated to greater HI values.
• The authors concluded from these results that soybean variety selection should be based on HI rather than overall biomass accumulation.
Study 2.
• Furrow-irrigated field studies were conducted in the 2019-2021 period on both loam and clay soils that are typically used for soybean production in the region.
• The study was conducted to evaluate the response of a MG 4 soybean variety to planting date [April 15-May 1 and 21 days after the first planting date] and row configuration [a single row in the center of 40-in.-wide beds, double rows spaced 10 in. apart in center of 40-in.-wide beds, and triple rows spaced 7 in. apart in center of 40-in.-wide beds].
• The seeding rate of 130,000/acre used in this study resulted in about 100,000 plants/acre at maturity. There was no lodging at any time during the studies.
• On both soil types, soybean grown in the earlier planting yielded more than that grown in the later planting [55.2 vs. 49.5 bu/acre and 61.8 vs. 51.9 bu/acre on the loam and clay soils, respectively].
• On both soil types, yield from single and double rows planted on the beds were nearly equal.
• The faster canopy closure of soybeans grown in the double vs. single row configuration of the later plantings indicate the importance of using narrower row spacings when soybeans are planted late.
• These results confirm that earlier planting of soybeans in the Midsouth will result in higher seed yield, and that late soybean plantings should be made in narrow rows.
For additional details about the conduct of these research projects and their results, click on the above-linked articles.
Composed by Larry G. Heatherly, Mar. 2025, larryh91746@gmail.com