The spring of 2018 will be remembered for too much rain and cold temperatures, which all contributed to one of the most challenging planting seasons in recent history. Farmers were concerned about getting their seed in the ground early enough to capture full yield potential, but one must take more than planting date into consideration. Soil conditions at the time of planting and the short-term weather forecast also play an important role in germination and emergence, as many were reminded when they saw poor emergence and weak stands.
With this in mind, the following guidelines will help you evaluate soybean stands and determine whether re-planting is necessary:
» PLANTING DATE: In a five-year study completed by Latham’s research team across multiple states, there was no significant yield difference between soybeans planted before May 15. We evaluated planting dates of late April and early May to mid-May. Planting on or before June 1 averaged 95% of expected yield. In fact, yields didn’t drop to the 85% and lower range until soybeans were planted after June 15. These results compare very closely to similar studies done by university researchers throughout our trade territory.
» PLANT POPULATION: Soybean stands can suffer from a wide variety of problems that will reduce population: hail, disease, insects, cold soil temps at planting time, compaction and planter failures. The biggest problem we find is that stand reductions almost never occur evenly across the field, so farmers must be diligent in scouting their fields and take the necessary time to evaluate their stands properly.
I recommend taking 10 stand counts in the area with the worst damage and 10 counts in the part of the field that was not affected or affected just slightly. At each point, measure off 10 feet of row and count the number of live, viable plants. You can take the average of your 10 points and compare them to the table on Page 3 to see how many plants per acre you have remaining.
A stand of 100,000 evenly distributed plants generally gives you optimum yield. Remember that as the growing season progresses, it is much more difficult to establish a good stand of soybeans. This means you might be better off leaving a stand of 75,000 plants on July 1 rather than trying to establish a new population. A stand of 75,000 on May 15, however, seems very inadequate and would warrant replanting.
Evaluating your stands early will help you identify concerns while there is still time to remedy the situation. If you have questions on evaluating your soybean stands, feel free to contact me or Phil Long.
