This week I spoke at a meeting of the Icelandic Green- and Groundskeepers Association at beautiful Keilir Golf Club in Hafnarfjörður. 

I described a 5 step method for estimating turfgrass nutrient requirements. Accurate estimates of turfgrass nutrient requirements ensure that turf is supplied with enough of each element that it requires, so that the turf can perform at a high level. At the same time, this process ensures that the growth rate of the turf is controlled, and that excessive fertilizer applications are avoided.

The 5 steps, which are explained in detail in the presentation slides and accompanying 4 page handout, involve these core priniciples:

1. The elemental content of fertilized turfgrass leaves is relatively constant
2. The amount of nitrogen used by the grass controls growth and uptake of the other nutrients
3. A temperature-based growth potential can predict how much nitrogen the grass will use
4. The MLSN (minimum level for sustinable nutrition) guidelines ensure that soil nutrient levels remain high enough to produce excellent turf conditions
5. By considering the previous points, mathematically, the minimum nutrient requirement can be determined

Slides from this presentation, entitled A Method for Estimating Turfgrass Nutrient Requirements, are available for download as a 2.8 MB pdf file. 

The 4 page handout (86 kb, pdf) to accompany the presentation provides additional explanations and references, along with links to more information on this important topic.

Nutrient requirements and turfgrass growth potential are closely linked to soil nutrient guidelines. At the seminar, I mentioned the Global Soil Survey, a new citizen science initiative that enlists turfgrass managers from around the world in the development and refinement of new soil nutritional guidelines.