Recent Soybean Planting Date Results

Research results continue to show the importance of early planting dates on soybean yield. This is due primarily to an increase in the seasonal capture of resources including sunlight, nutrients, and water resulting in more main stem nodes which produces more pods and more photosynthate production and time to fill them.

Corn is a sink limited crop, meaning it has a limit of one ear each plant can fill regardless of the available water, nutrients, and light. On the other hand, soybeans are a source limited crop meaning their sink, (the number pods and beans) can flex and yield is limited by the source, mainly available water, nutrients, and sunlight, which can continue to fill the sink. Strategies to maximize one of the key sources, the seasonal sunlight capture starts with early planting of soybeans.

Of the 166 research trials conducted by BASF seed agronomists from 2016 to 2023 across IA, IL, IN, and OH, results show that soybean yield was reduced by 0.5 bushels per day after the first fit day for planting. 

Soybean plants gain both above ground canopy and below ground root growth benefits from early planting.

📸: BASF Employee Bill Backhaus, BASF Agronomic Services | date of planting affect on root growth

Researchers saw an extended duration of both the vegetative and reproductive phases of growth with earlier planting dates. It has been shown that early planted soybeans take better advantage of longer day-lengths with more days of growth prior to the summer solstice. 

📸: BASF Employee Bill Backhaus, BASF Agronomic Services | date of planting affect on emergence and early growth

Critical soybean growth stages benefit from more solar radiation as the longer day-lengths fuel the primary drivers of soybean yield including increased numbers of nodes on the main stem providing more available flowering and pod sites, as well as more photosynthate production during the R1 through R5 growth stages.

📸: BASF Employee Bill Backhaus, BASF Agronomic Services | date of planting affect on R3 date

With an earlier and more robust canopy, shading of rows reducing weed competition as well as moisture retention also benefits the plant and improves yield. Research conducted by BASF agronomic services has also shown that the increased yield with earlier planting dates can be realized across a wide range of soybean relative maturities. Comparing soybeans planted April 29^th to the same varieties planted June 4^th, yield was increased by 0.6 bu/a with 1.6 to 2.1 RM, 0.47 bu/a with 2.2 to 2.7 RM, and 0.5 bu/a with 2.8 to 3.4 RM.

Of course, there is a practical limit to how early soybeans can be planted, with regard to soil fitness, temperature, and even crop insurance considerations.  Researchers prescribe minimizing some of the risk of early soybean planting by using a complete seed treatment such as Obvius® Plus as cool soil temperatures can enhance early soybean diseases. Balancing the risks, yield benefits have been seen by those who have pushed the envelope earlier than previous conventional thinking that soybean planting should wait until corn planting is completed.

Footnote: Photos are from trial at Lewis, Iowa 2023 using Xitavo(TM) XO 3130 soybeans treated with Obvius Plus (0.71 fl oz) + Poncho Votivo ® (1.02 fl oz) + Relenya ® (0.1 fl oz) + ILEVO ® (1.18 fl oz) / 140K. For more information on soybean planting date result find your local BASF Agriculture Solutions advisor at the BASF website.

Obvius, Poncho, Relenya and Ilevo are registered trademarks of BASF.