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Pertinent Results from Midwestern Soybean Planting Date Survey

Past research and current soybean yield trends in the Midsouthern U.S. have firmly established that early planting is a significant contributing factor to higher yields in the region. In fact, the effect of numerous inputs–e.g. irrigation–is enhanced when applied to early-planted soybeans.

Producers have a plethora of input choices–e.g. seeding rate, seed treatment, variety maturity group, inoculant, herbicides–to apply to any soybean planting to ensure the expression of its full potential. However, for any input(s) that is(are) chosen as a potential yield enhancement, there is an associated cost. Thus, producers are left with a quandary–which inputs do I use and which should I leave out? Will the chosen inputs result in an economic gain, and will the excluded inputs result in an economic penalty? These questions must be considered with any soybean planting decision.

An article titled “Management strategies for early- and late-planted soybean in the north-central United States” that is authored by Matcham et al. appears in Agronomy Journal ( The results contained in this article are derived from producer surveys that queried management decisions applied to 5682 fields in 10 midwestern U.S. soybean states during the 2014-2016 growing seasons. The early plantings referenced in this article generally occurred from mid-April through early May, while the late plantings occurred from late May through early July.

Even though the results reported in this article are from the midwestern states, pertinent results that should be considered for Midsouth soybean plantings are highlighted and related to information sources (see below links) that contain information for Midsouth soybean production.

•   In early-planted fields, management factors that were most associated with enhanced yields were insecticidal seed treatment and seeding rate. Greater yields were associated with a lower seeding rate that was generally less than 155,000 seeds/acre. (Click links to below articles for Midsouth guidelines for these inputs).

•   In late-planted fields, insecticidal seed treatments were not associated with a yield change. Herbicide application timing was often associated with greater seed yields. Greater yields were associated with fields that received both a PRE- and POST-herbicide applications compared to fields that received only a PRE or POST application. Lower yields were obtained from fields that received only a POST application. (Click here to access articles on this website that discuss herbicide use on Midsouth soybeans. The vast majority of weed control guidelines for Midsouth soybeans recommend use of both PRE and POST herbicides).

•   Both foliar fungicides and insecticides improved yields in early- and late-planted fields. However, the authors state that the association between greater yields and pesticide application could (likely will) change among growing seasons. Therefore, they recommend that producers base their insect and disease management on IPM guidelines rather than making prophylactic applications of pesticides. Also, market prices should be considered with these application decisions since profitability likely will be lacking if they are applied needlessly. (Click links to below articles for Midsouth guidelines for these inputs).

•   Across all environments sampled in this survey, early–planted soybean fields yielded more than late-planted fields.

•   These results do not indicate a single management factor that is responsible for higher soybean yields from any planting date. Thus, management/input decisions should be region- and planting date-specific based on field history and local conditions. (Since Midsouth soil, environmental, and weather conditions are quite different from those in the midwestern U.S., information sources that present guidelines for Midsouth soybean production should use results from research conducted in the Midsouth environment where the crop will be grown).

•   Interestingly, the authors state that “prophylactic use of fungicide- and insecticide-treated seed does not provide a consistent economic benefit”. This may be true from the results of their survey, but the use of seed treatments in Midsouth plantings has never been or should never be based on a hoped-for yield increase from their use. Rather, soybean seed treatments–especially fungicide seed treatments–in the Midsouth should be used as insurance against stand failures that can occur, and that will result in a later-planted crop with subsequent lower yields than those from the earlier failed planting. Also, seed treatments should allow for fewer seed to be planted to achieve an intended plant population. This will save money and likely will pay for the seed treatment. (Click the link below to access seed treatment information for Midsouth soybean plantings).

Producers are encouraged to access the information contained in the following White Papers on this website. These articles contain up-to-date information that Midsouth soybean producers can use to make decisions for the 2021 crop.

“Management Decisions Based on Planting Date”

“Soybean Seeding Rate and Plant Population”

“Soybean Seed Treatments and Inoculants”

“Guidelines and Resources for Managing Soybean Diseases”

“Soybean Insect Management Guide”

Click here to access results from MSPB’s Soybean Management Practices Surveys that provide insight into prevalent production practices used by Mississippi soybean farmers to produce yields that exceed the national average.

Composed by Larry G. Heatherly, Nov. 2020,