Ross Braun and Aaron Patton published a research article now available:
Braun, R. C., & Patton, A. J. (2022). Perennial ryegrass (Lolium perenne) culm and inflorescence density in lawns: Effects of nitrogen fertilization and scalping timing and height. Crop Science, 62, 489–502. https://doi.org/10.1002/csc2.20665