Over the course of a week last October, I spoke about turfgrass nutrient requirements in Hawaii, Washington, Idaho, and Oregon. Each time, I discussed this topic in a slightly different way.

With a look at these presentation slides, which all essentially cover the same topic, but are different in their title and in their approach and in the localized estimates of nutrient use, one can get a good overview of how I go about answering the two most important questions of turfgrass nutrition. These are 1) Do we need to add this element as fertilizer? and 2) If so, how much of the element do we need to add?

As you will see from these slides, I suggest nutrients be supplied to ensure that there is enough present to meet all the grass requirements. That is, make sure there is enough of each element so that the grass use of that element can be met, while still keeping a reserve amount of that element present in the soil. And although I didn't write it on the slides, I would have said it during the presentations. It is silly to add more of an element than the grass can use or than the soil can hold.

First, from Hawaii, where we talked about The secret to preventing nutrient deficiencies: why K fertilizer is almost always required but Ca is not, and the controlling role of N, among other examples to illustrate the point.

Then, in Washington, I talked about Leaves of Grass: a practical understanding of turfgrass nutrient use.

Next was in Idaho, where the title was A Modern Method for Estimating Turfgrass Nutrient Requirements.

And then was at Oregon State University, where I had a chance to teach a session of the Turfgrass Management class in the Horticulture Departiment. Getting right to the point, since I only had one chance at it, I taught Everything you need to know about turfgrass nutrition in 1 lecture.