This question came in the mail:
As to the MLSN guidelines that you have been a big proponent of, how do they apply to growing in a new course. I have wondered if they are more geared toward once a turfgrass becomes established and you are in maintenance mode.
I have a new course that I have been supplying our [grass variety] and they are practicing the MSLN approach using only liquid applications (via tank applications as they haven’t installed their fertigation yet). I would like to see the course further along in coverage of the [grass] based on the amount of time it has been planted. Just would like your thoughts on this program as it relates to a grow-in. I have always subscribed to applying fertilizer and push the turf so as to maximize establishment then go into maintenance mode once grown in.
Would appreciate your comments.
I agree with you that for grow-in I would be pushing turf to get establishment in a reasonable amount of time and after that I would slow the growth to produce whatever growth rate is required for the amount of traffic on that surface. The MLSN approach is a way to ensure that no matter how fast the grass is growing, it will certainly be supplied with enough K, P, Ca, Mg, and S.
Adjusting the N rate during a grow-in will change the rate at which the turf establishes. MLSN makes no recommendation for N rate, and simply links expected nutrient use to the growth rate to ensure that the elements other than N are supplied in adequate amounts at whatever rate the grass is growing. Thus, I think the MLSN approach is fine for a grow-in, but I would be especially sure to make the calculations correctly, especially for P, and in the case of [grass variety], for K as well, to make sure there remains a buffer in the soil of those elements no matter what the grow-in rate is.
I think pushing the turf is all about N; if I withheld N, and tried to push the turf with P and K, nothing would happen. In that case, there is more than enough P and K, but not enough N, so the turf doesn’t get pushed. If I would have not enough P and K, and try to push the turf with N, nothing happens again. That’s because the P and K are deficient. But fertilizer recommendations based on the MLSN guidelines are caclulated to ensure the grass is supplied with more than enough P and K (and Ca and Mg and S) so that the deficient situation doesn’t happen, no matter what the N rate (or establishment rate) is.
For some example calculations of fertilizer rates based on the MLSN guidelines, see: