http://www.agvise.com/summaries/ND_SD_MNnutrientSummary2011.pdf

A few things that jumped out to me were the number of soil samples coming back with P values in the single digits. I think this is a component of two things: 1. Record high Phosphorus prices a few years back slowed people down from applying as much phosphorus. 2. Increased crop yields are outpacing the amount of fertilizer that is being applied and we are mining the soil. The other trend that stuck out to me was the steady increase in soil samples that are done as either grid or zone samples. Managing fields by zones is a great way to make sure crop inputs are being applied to the places in the field that will give you the most benefit.