Soybean yields increase about 15% if recommended rates of phosphorus fertilizer are applied when soil test levels are low or very low, says George Rehm, soil scientist with the University of Minnesota Extension Service.
In addition, new research shows that the added phosphate may increase protein by about 1%.
“Profit from the added phosphate can be substantial,” Rehm says. The value of the added yield can be in the range of $42-56/acre with $7 soybeans. The fertilizer cost for the increase is about $12.50/acre.
The value of the additional protein could be $4-5/acre, Rehm says. So the net benefit of the phosphate fertilization is in the range of $29-44/acre after the cost of the phosphate fertilizer is subtracted.
“Although initial research shows the positive effects of phosphate fertilization on soybean protein, there's much more to learn and this requires extensive field research,” Rehm says.