"I started using the MLSN guidelines and was amazed with the huge impact this made"
I really like the technical aspects of turf nutrition, specifically identifying just how much of each nutrient is required to produce the desired surface conditions. This necessarily involves numbers such as the amount of the nutrient in the soil, the amount applied as fertilizer, how much labor was involved with the application, and the cost of those nutrients.
If you are also interested in these things, then I am sure you will find Jason Haines' post on this topic of great interest. He summarized this in his post entitled Fertilizer Use 2014, but he didn’t just limit the report to this year. The post shows the data of fertilizer use and cost for the past six years.