Phosphorus
View Larger
Research conducted by Isaac Mertz, Iowa State University, photo by Ben Pease, Iowa State University. Ben tweeted this photo illustrating the response of bentgrass to application of 0.5 lbs P/1000 sq ft (2.4 lbs 12-48-5/1000 sq ft) spray applied. The response is dramatic. Even though we would expect to see an increase in soil P of about 15 ppm, no increase in soil P was detected. In Ames, IA, bentgrass GP suggests that 0.07 lbs P/1000 sq ft per month (2 ppm) is needed during the summer. Not much P is needed to maintain healthy bentgrass and the MLSN guideline of 21 ppm M3 P is generous - possibly too generous.
