Narrow rows are much more important and more players on the field are needed as the planting date gets later. Whereas 150-160,000 established plants per acre are adequate for full season soybeans in May plantings, this should be increased to around 175,000 for planting in the first half of June and 200,000 for the last half of June or later.
A rough rule of thumb is that soybeans following barley average about seventy-five percent of the yield of full season beans that are planted in mid-May. After wheat, this average drops to fifty percent. Ohio State estimates that after wheat harvest, soybean yield potential drops an average of one bushel per day. If you're going to go for it, consider harvesting wheat at a higher moisture content and dry it for better test weight and get a jump on planting soybeans.
For soybeans planted in June, varieties up to late group III or early group IV can still be used. If planting in early July, back off to a mid group III. If planting even later, drop down to an early group III.
When is the last time you calibrated your drill for soybeans? Did you know that with 7" rows, one extra seed per foot of row results in over 70,000 more seeds planted per acre? The following table provides the approximate plant stand, based on 85% emergence at two seeding rates for 7" and 7.5" rows, respectively.
|Seeds/ft||Plant Stand||Row Spacing|
These stands could easily be 10-15% lower for no-till or other adverse planting conditions.
Did you know that with 7" rows, one extra seed per foot of row results in over 70,000 more seeds planted per acre?
Sometimes questions arise about the benefit of applying nitrogen on soybeans, particularly in a double crop situation. In a Penn State research trial, rates of nitrogen in fifty pound increments from zero up to two hundred pounds per acre were tested. Although the soybeans looked a little greener and slightly taller there was no yield advantage from adding nitrogen in both tilled and no-tilled tests.