Soybeans were scouted at the V3 growth stage and yellowing of upper (newer) leaves were observed in areas across the field. These soybeans were planted in late-April and biosolids were applied 3-4 weeks prior to planting. Inconsistency of biosolid application across the field was observed.
This issue was confirmed by an NC State Extension Specialist as Zinc Toxicity following review of soil test reports. In this environment high Zinc and low pH have been issues in past years. The application of the biosolids this season aided in the accumulation of metals like Zinc, which lead to these symptoms. There are limited remedial applications this season.