Light

Turf stories as Twitter Moments

I’ve gathered some collections of tweets into moments for easy viewing in sequence. I previously arranged these on Storify, but that service has shut down. Here’s a quick description of these moments.

Is morning sun the most important for turf? It depends.

I used Storify to string together some related tweets and images over the past few years. That service is shutting down. I’ve moved a “story” about light, shade, and time of day to this Twitter moment.

"I really wish that I could hear this presentation"

That’s what Jon Scott wrote to me on October 7, 2014, after I shared the slides from my shade talk at the Northwest Turfgrass Association conference. We’ve been having a back and forth about this ever since.

GP is a number. It's explained here in photos and words.

Every now and then I get some questions about the temperature-based growth potential (GP). The most recent question was about relative humidity: “I am curious about the effect relative humidity has on growth potential?

Is it normal to be cloudy like this?

On 17 July 2016, I was in the Tokyo area with Jim Brosnan. The daily light integral (DLI) in Tokyo that day was 14.2 mol/m2. Jim asked me if it was exceptionally cloudy that day.

Misleading, irrelevant, or just plain wrong

I taught five seminars at the Northern Green Expo in 2016. The (New) Fundamentals of Turfgrass Nutrition Nutrient Use by the Grass and Nutrient Supply by the Soil

A summary of photosynthetically active radiation for 1 year at Tokyo

This chart (download at full size) shows the average photosynthetic photon flux density (PPFD) for each hour of 2015 at Tokyo. The daily light integral (DLI) is the number written in black at the top right corner of each facet in this chart.

Estimating daily light integral (DLI) in Tennessee

After I wrote about no problem DLI levels, Brandon Horvath asked if I could get DLI for some cities in Tennessee. For a description of how I made the calculations, see Estimating daily light integral (DLI) in 4 Tennessee cities.

40, 30, & 20

For warm-season grasses on putting greens, I propose a no-problem DLI of 40 for bermudagrass, 30 for seashore paspalum, and 20 for zoysia. Above that, and there is enough photosynthetically active radiation (PAR) to easily manage the species. Below that, and it won't be no problem anymore.

A DLI Index

I’ve shown the sum of the mean daily temperature over 2014 for four locations: Fukuoka and Tokyo in Japan, Holly Springs in Mississippi, and Watkinsville in Georgia. Fukuoka had the highest accumulated temperature, then Tokyo, then Watkinsville, and the coolest of those four locations was Holly Springs.