This is the handout for my seminar at the Hawaii GCSA annual seminar, held at the Prince Hotel Waikiki on 3 October. The general topic is turfgrass nutrition, and specifically how to make sure there won’t be any nutrient deficiencies. For a subtitle, I added why K fertilizer is almost always required but Ca is not, and the controlling role of N, among other examples to illustrate the point.

The quick reason why that subtitle is important to understand is this. Adding more nitrogen (N) makes the grass grow more, which naturally increases the demand of all other nutrients. That makes sense, because as the plant grows more, it produces more leaves and stems and roots – it is a bigger plant. And when there is a bigger plant, in order to maintain nutrient levels in the plant, more of every nutrient will be required.

But why is potassium (K) almost always required as fertilizer, but calcium (Ca) is not? That is because grass in Hawaii, over the course of about a year, will use more K than is available in the soil. So if K is not added as fertilizer, the soil K will get so low that plant uptake of K may be too low. With Ca, that isn’t the case. The amount of Ca in the soil is large, and the amount used by the grass is less, so even over a span of multiple years, the grass can obtain all the calcium it will use from the soil.

Here are the presentation slides:

The secret to preventing turfgrass nutrient deficiencies from asianturfgrass

For more information on this topic, see the Asian Turfgrass Center’s posts tagged fertilizer.

Links mentioned in the presentation:

I also spoke for a while about minimizing pesticide amount, toxicity, and impact. More information about that is available here. You will find slides on that topic, along with links to the EIQ and the Documenting Sustainability article.