Boosting Soybean Yields - The Power of Early Planting

A study by Iowa State University found that planting soybeans early can lead to higher yields. The study found that soybeans planted 14 days earlier than the normal planting date had an average yield increase of 8.2%.

The study's authors believe that the early planting date allowed the soybeans to canopy more quickly, which maximized light interception and limited weed competition. They also found that the early-planted soybeans had more nodes per plant, which is a key determinant of yield.

A soybean plant typically has 20 nodes. Each node can produce 1-4 pods, but only about 50-100 pods per plant will set seed. The majority of the yield comes from nodes 6-13.

The optimal node number on June 21st is 6 or more nodes per plant. That increases to 18-20 by the end of flowering. The total node number is affected by the relative maturity (RM) of the variety, with longer RM varieties typically having 1-3 more nodes.

Early planting also results in a longer reproductive window. The time period from R1-R6 is longer, which is when the soybeans are flowering and setting pods. This is important because it gives the soybeans more time to develop pods and seeds.

In addition to planting early, there are other things that farmers can do to increase the number of nodes per plant. These include using a good seed treatment and inoculation, as well as applying starter fertilizer. Potassium aids in nodulation and the regulation of plant stomata and photosynthesis production, which can increase the number of nodes.

Farmers can also help to retain flowers by using sugars. PFR research has shown that the use of sugars can help to retain flowers. One extra pod per plant is equivalent to 2 bushels per acre.

Finally, the number of seeds per pod and seed size are also important factors in determining the final yield. Healthy soybean plants should average 2 to 2 ½ seeds per pod. Seed fill begins at the R4 growth stage and is complete by R6. The rate of root growth slows as the seed growth begins, leading to increased moisture sensitivity during this period. Late-season moisture can increase the seed size by extending the seed fill period.

By following these tips, farmers can increase the number of nodes per plant and improve their soybean yields.

Photo Credit: gettyimages-zoran-zeremski