Dr. Alex Lindsey, Associate Professor of Crop Ecophysiology & Agronomy, walks us through his current research project on how cold temperatures and water can affect early planted soybeans within the first 24 hours of planting.
How does cold temperature and water affect germination and emergence?
We have been studying how cold temperatures and water affect soybeans under ultra-early planting conditions using some lab experiments. We planted soybeans into field soil (starting at 20% or 60% available water content) at 1” (shallow) or 1.5” (normal) planting depths, and exposed them to different combinations of cold temperatures and water treatments during the first 24 hours after planting (Table 1). After the first 24 hours, we raised the temperature in the chamber to 70°F and measured emergence.
Table 1. Temperature and water treatments evaluated during the first 24 hrs after planting.
Preliminary results suggest that no water application (even if temperature dropped to 35°F) resulted in the greatest emergence (75%) after 11 days. Water application immediately after planting, regardless of whether it was 50°F or 35°F, cut the emergence totals in half. Application of ice after planting was less damaging to emergence but still reduced germination compared to where water wasn’t applied. This suggests that avoiding precipitation within the first 24 hours of planting is key to ensuring good emergence.
Does planting depth matter?
Interestingly, shallowly planted seeds (1-inch depth) had slightly lower emergence totals (10-15% less) compared to those planted at the normal depth of 1.5-inch when the soil was drier (20% available water content). The effect of planting depth on emergence was less noticeable when soils had 60% available water content at planting.
These results suggest it is possible that a 1.5-inch planting depth for ultra-early planting may result in better emergence than a shallower planting depth, but these results should be field tested before further recommendations can be made. Avoidance of precipitation of any sort in the first 24 hrs after planting was key to ensure best emergence with cold temperatures.
What is happening in the field?
The Western Agriculture Research Station is still the only location planted as much of the state has been water-saturated with little available suitable field work days since March 25th. However, southern Ohio last week was dry enough for planting in areas, so planting date 2 went in on April 16th (Table 1).
Planting date one (March 25) in both corn and soybeans have emerged! The high temperatures through last weekend helped to accumulate the required GDD for plant emergence (Table 2). The corn is between VE and V1 (first leaf collar) and the soybeans have the cotyledons coming through the soil (Figure 1). Temperatures were lower at this location the weekend of April 20th; cold injury will be scouted for this week.
Figure1: Corn and soybean on April 18 (planted on March 25) at the Western Agricultural Research Station in South Charleston, Ohio.
Table 1. The planting date conditions for planting date two at the Western Agricultural Research Station.
Table 2. Weekly weather conditions for planting dates one and two at the Western location with day of planting, soil, air temperature averages, and Growing Degree Days (GDDS) from April 15 to April 21. Information from CFAES Weather System (https://weather.cfaes.osu.edu/).
Episode 4 of battle for the Belt is now available: https://www.youtube.com/watch?v=T5_QXF-Px7s