Soybeans have a different, more tap-rooted habit than grassy plants like wheat and corn, which often respond more efficiently to banded fertilizer. Affect of P placement on soybeans, NB, 1981. P test very low. If soil test levels are low to very low, then a separate application of broadcast P is justified. However, if soil test levels are medium or higher, the level of response of soybean to P fertilizer is small, not justifying a separate P application.
Soybeans are excellent scavengers of P at medium or higher soil test levels.
It would be better at medium or higher soil test levels to front-load the crop prior to soybeans or apply more to the crop following soybeans than to apply P to that soybean crop. The most common fertilizer practice in the central US soybean belt is applying extra P to the previous corn crop and allowing soybeans to utilize residual P from the soil. The practice has been successful for over 30 years. Even though a broadcast application of P may result in several more bushels of soybeans than a banded application, some producers will elect to apply P with the seed. With air-seeders, risk to soybeans will be decreased with fertilizer spread across the seed zone.