From AgProfessional:
"Many farmers are producing over 300 bushels per acre every year in yield contest fields. Seed companies are consistently growing 300-plus yields inside the greenhouse and in test plots, so genetics is not the limiting factor. In order for average corn yields to continue to increase, farmers need to consider ways to reduce yield-limiting factors in their production systems.
There are six specific components that are biologically-based and can enhance your soils health and productivity."
Read more here.