Last week, a turfgrass scientist wrote to me with some concerns about the MLSN guidelines. My correspondent was particularly concerned about me being too dismissive of previous research results showing a beneficial effect of adding more potassium than the grass can use. 

These were really good questions, and I took the opportunity to write a full response, which I am sharing here. The conversation touches on the development of turfgrass soil testing guidelines, peer review and journal publication, and most extensively, how we can interpret the results of potassium experiments.