Late planting of soybeans: Management considerations
Soybean planting progress in Kansas is ahead of last growing season but still there are soybean fields to get planted. In the latest Crop Progress and Condition report from Kansas Agricultural Statistics (June 19, 2016), soybean planting was at 89% complete, near the long-term average of 86%.
Where soybean planting has been delayed, producers should consider a few key management practices. Planting soybeans in the right soil conditions is essential for establishing an adequate soybean canopy and improving chances to increased yield potential.
Figure 1. Late-planting soybeans (June 10) into adequate soil conditions. Photo by Ignacio A. Ciampitti, K-State Research and Extension.
Maturity group factor: From our planting date x maturity group study in 2014 and 2015, late planting did not clearly result in a yield reduction at the dryland sites, and caused only a minimal yield reduction at the irrigated site. Medium maturity groups (ranging from 3.8 to 4.8) yielded better, depending on the site and growing season evaluated (Fig. 2 and 3). More information related to this study can be found in eUpdate issue 563 April 15, 2016 at: https://webapp.agron.ksu.edu/agr_social/eu_article.throck?article_id=900
Figure 2. Soybean yields with different planting dates (early, mid, and late) and maturity groups (E = early, M = medium, L = late maturing groups) at five locations across Kansas for the 2014 growing season.
Figure 3. Soybean yields with different planting dates (early, mid, and late) and maturity groups (E = early, M = medium, L = late maturing groups) at five locations across Kansas for the 2015 growing season.
Seeding rate factor: Increasing the seeding rate of late-planted soybeans by 10-20% as compared to optimal seeding rate can help compensate for the shortened growing conditions. Research information on seeding rate and late planting of soybeans is currently being investigated further, with more updates on this topic in future issues of the Agronomy eUpdate. The same soybean cultivar planted early in the planting window, under normal conditions, will develop nearly 50% more productive nodes than when planted in late June: 19-25 nodes when planted early vs. 13-16 nodes when planted late. For soybean seeding rates and optimum plant populations, see eUpdate issue 565 April 22, 2016 at: https://webapp.agron.ksu.edu/agr_social/eu_article.throck?article_id=912
Row spacing factor: Information on late-planted soybean across multiple row spacings suggests that narrow-rows (e.g. 7” or 15” vs. 30”) can hasten canopy closure, increasing season-long light interception, weed suppression, and potentially improving biomass and final yield. In some cases, the likelihood of finding yield responses to narrowing rows increases as the planting is delayed later in the season.
Finally, proper identification of soybean growth stages can make a difference in yield. We have worked with the United Soybean Board and the Kansas Soybean Commission recently to produce a soybean growth and development chart. It can be downloaded at:
More information about key aspects of each growth stage and management practices can be found in that soybean chart.
Ignacio Ciampitti, Crop Production and Cropping Systems Specialist
Doug Shoup, Southeast Area Crops and Soils Specialist
Stu Duncan, Northeast Area Crops and Soils Specialist