Build and Maintain Vs. Nutrient Sufficiency Approaches

I was going to attend an online course on Build and Maintain vs. Nutrient Sufficiency Approaches to recommendations. After some online research, I probably won't. We really seem to follow more of a build and maintain philosophy even though we don't really take that approach. The sufficiency philosophy says put on only what you need in order to grow a crop this year. We might do that in a given year, but that tends to run down the soil in that on a good soil you can get by with less than the crop takes off until the levels get down to where you are forced to add full removal rate. Sufficiency does not allow any flexibility for years like the past few when prices go out of sight. While we don't continue to make deposits in the soil bank until levels are at a huge excess, there is merit in having a small savings account.

Sufficiency is a good way to manage Nitrogen since it is impossible to build up anyway. The N-Rate calculator http://extension.agron.iastate.edu/soilfertility/nrate.aspx takes the sufficiency approach.