I received that question by e-mail. It's a good one to answer in that I can point out the differences between the SLAN (sufficiency level of available nutrients) and MLSN (minimum levels for sustainable nutrition) guidelines.
1. The SLAN guidelines are in this article.
2. The MLSN guidelines are in this file.
3. This article in GCM points out why the MLSN guidelines were developed and how to use them. We wrote:
Conventional guidelines [the SLAN guidelines] are not only complex, they are also relatively static, without regular or systematic updates. However, regular updates seem like a good idea, because many research projects suggest that high-quality turf can be produced at levels below the conventional guidelines.
4. I can't stress enough how much I prefer the MLSN approach to SLAN. First, SLAN guidelines are not updated and no one is supporting them. MLSN are under continuous review and development. Second, MLSN allows one to calculate a fertilizer requirement for any grass grown anywhere in the world. Please read about SLAN for turfgrass, try to calculate a fertilizer requirement, and then tell me how it is done. I can't figure it out. And I bet you can't either. The SLAN guidelines are nice to look at in a table, but they are ambiguous in the amount of fertilizer that will be recommended.