- One of the main factors that affects soybean yield is the planting date. Previous studies indicate that early planting dates can achieve higher soybean yields by avoiding late-summer drought and reducing the incidence of disease and insect infestations.1 However, delays in planting are common when double-cropping and in years with excessive rainfall.
- Selecting the best maturity group (MG) for a given planting date and location can help farmers maximize yield potential.
- Current production system norms in the Midsouth consist of MG 4 and MG 5 soybean products planted on dates ranging from late-March to early-July with products planted in mid-April to mid-May having the highest yield potential.
- This demonstration was conducted to evaluate the yield response of Asgrow® brand soybean products of different MGs to planting date.
- An additional large plot yield trial was designed to determine which soybean products are adapted for the growing conditions at the Scott Learning Center.
Research Site Details
Demonstration Plot Details
Plot size was 0.1 acre, non-replicated, and managed according to standard agronomic practices. A total of 15 soybean products ranging from MG 00 to MG 5 were planted at four different planting dates ranging from early to late.
- 4/20/2018 – Planted into relatively cold conditions
- 5/10/2018 – Normal planting
- 5/30/2018 – Late/normal planting
- 6/20/2018 – Late planting simulated behind wheat/20/2018 – Late planting simulated behind wheat
Large Plot Details
Plot size was 0.54 acre (12 rows each; 600 feet long), non-replicated, and managed according to local practices and harvested with commercial equipment. Data was adjusted for moisture as needed. A total of 14 soybean products ranging from MG 1 to MG 5 were planted at two planting dates.
A desiccant to aid in harvest was applied to both demonstrations when soybean seed pods were brown in color. Plots were then harvested 5 to 7 days later. A range of harvest dates was used based upon when soybean products reached maturity.
Understanding the Results
Demonstration Plot Results
- Most of the soybean products tested were shorter in height when planted on the April 20 date (Figure 1). Soybean planted early will begin flowering very soon after emergence and result in shorter than desired plant heights. The pods of these plants are closer to the ground and harvest efficiency is reduced. This was also the case in the large plot demonstration.
- The number of days to harvest was reduced across the range of planting dates compared to the April 20 date (Figure 2). Earlier planting dates allow for a longer growing season with a longer duration in the reproductive stages and the reproductive stages occur during the longer days of summer.
- The mid MG 4 soybean products planted in early May had the highest yields in this demonstration (Figure 3). This response to planting date was as expected and is typical of the Midsouth system. AG32X8 brand (MG 3.2) was the earliest product that may have high enough yield potential for planting consideration at Scott, MS.
Large Plot Results
- Similar yield results were found in the large plot demonstration trial (Figure 5).
- Soybeans delivered to an elevator below or above 13% moisture, the elevator standard, lose potential profit. At greater than 13% moisture, there is a moisture dock on the scale ticket. With less than 13% moisture, profit is lost because there are fewer bushels to sell. By monitoring soybean moisture levels and selecting the optimum harvest date, profits are then maximized (Figure 4 and 6).
- Based on these trials, it appears that time in the field could be saved by planting a relatively early (for the region) MG soybean product into warm environmental conditions that favor rapid growth; and that very early soybean products (3.2 MG) may offer acceptable yield potentials in a shorter season than some of the historical practices (MG 5 or later planted in June) (Figures 3 and 4).
- Growers should tread carefully in pursuing these practices. These early MG soybean products need to be tested and proven in Midsouth environments before adoption. Soybeans delivered to an elevator below or above 13% moisture, the elevator standard, lose potential profit. At greater than 13% moisture, there is a moisture dock on the scale ticket. With less than 13% moisture, profit is lost because there are fewer bushels to sell. By monitoring soybean moisture levels and selecting the optimum harvest date, profits are then maximized (Figure 4 and 6).
What Does This Mean for Your Farm?
- This study found that yield potential can start to decrease with late planting dates. However, some potential exists to shift toward earlier maturity soybean in later plantings without significantly decreasing yield potential (Figures 3 and 4).
- When similar yield potential can be achieved among different MG soybean products, shorter-season soybean products could offer an incentive by potentially reducing irrigation and late-season management costs, avoiding late-season insect and disease stress, and benefiting from earlier harvest dates and the potential for higher market prices.
- This work could have utility in situations where delays in planting result from undesirable environmental conditions.
- Further study is needed to confirm the results of these trials.
1Heatherly, L.G. January 2016. Management decisions based on planting date. Mississippi Soybean Promotion Board.http://www.mssoy.org