To better your agronomic practices, acquire as much data as possible and start variable rate application of all inputs.  If you put more or less of something in a certain area of a field and the crop does not respond to the change, that area of the field has something else going on with it than what you or your agronomist anticipated.  The key here is if you do not measure what you harvest in a site specific manner, you can not adequately adjust your variable rate prescription.  Many argue that measuring protein is a waste of time because you are not paid for protein but protein content can illustrate variances in your field and show where you need to soil/tissue test.   You cannot go wrong with acquiring more information, and if you don't start measuring today, you can't start to better your input dollars tomorrow.