Uneven Soybean Emergence
In many areas of Ohio, soybeans are emerging unevenly. This is something that I observed last week in western Ohio. Most of the soybeans were at the VC stage (unifoliate), but there were areas that had not yet emerged. The soil was very dry and crusted over which contributed to some of the uneven emergence. Where we didn’t see any soybeans emerged, we dug up the seed and saw the soybean crooks (hypocotyls) emerged from the seed. I have not been back to western Ohio to check the field, but with this weekend’s rainfall, more soybeans are likely to have begun breaking through.
Uneven soybean emerged related dry soil has led to questions about replanting. Before replanting due to an uneven stand, do two things. First, dig around in areas where there are no plants. If you find seed that is healthy and germinated, but just not broken through – you can wait. The soil temperatures have finally reached optimum germination conditions, with a little bit of moisture they will continue to emerge. We saw this last year, when soybeans sat in the ground for a full 6 weeks before they received enough moisture to germinate. If you find, dead seedlings (disease) or no seed or seedlings (insects), then follow the next step very closely.
Second, take a stand count to determine the number of plants remaining. To quickly estimate stand, count the number of plants in 70 foot of row for 7.5 inch row spacing, 35 foot of row for 15 inch row spacing, or 17.5 foot of row for 30 inch row spacing. These counts represent 1/1000th of an acre (i.e., 120 plants in 35 foot of row grown at 15 inch row spacing represents a stand of approximately 120,000 plants per acre). Previous research conducted by the Ag Crops Team at Ohio State, indicates that soybean populations of 50,000 plants per acre yield approximately 15% lower than soybean populations of 175,000 plants per acre. Also, keep in mind soybean yield is decreased by approximately half a bushel per acre every day when planting later than mid-May. When considering replanting soybean, make sure to take into account existing stand, yield loss due to late planting, and the cost of additional seed (we recommend higher seeding rates when planting in June).
Source : osu.edu