Late planting of soybeans: Management considerations
Soybean planting progress in Kansas is ahead of last year’s growing season but still there are soybean fields to get planted. In the latest Crop Progress and Condition report from Kansas Agricultural Statistics (June 11, 2017), soybean planting was at 80% complete, ahead of the long-term average of 72%.
To look a little bit to the historical planting dates for our state, in recent decades, Kansas producers have been planting soybeans slightly earlier -- at the rate of about one-third day per year (Fig. 1). In the past three growing seasons (2015-17), however, the “50% planting date” mark was achieved at a similar time (first week of June) statewide. Moreover, the same “50% planting date” mark was attained in 1980 as this current growing season, averaging 50% planting progress by June 1.
Figure 1. Trend in the date at which 50% of planting progress was achieved for soybean from 1980 to 2016 in Kansas. Source: USDA-NASS.
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 2. 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, 2015 and 2016, 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 (Figs. 3, 4, and 5). More information related to this study can be found in Agronomy eUpdate issue 626 April 14, 2017 at: https://webapp.agron.ksu.edu/agr_social/eu_article.throck?article_id=1335
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 2014 growing season.
Figure 4. 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 the state of Kansas for 2015 growing season.
Figure 5. Soybean yields with different planting dates (early, mid, and late) and maturity groups (E = early, M = medium, L = late maturing groups) at three locations across the state of Kansas for 2016 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 Agronomy eUpdate issue 627 April 21, 2017 at: https://webapp.agron.ksu.edu/agr_social/eu_article.throck?article_id=1339
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 a positive yield response to narrow 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