Growers who do not properly calculate their fertilizer rates run the risk of spending too much on fertilizers with little return.
Photo: Adobestock

In his role as an assistant extension professor at Mississippi State University, Dr. Geoffrey Denny works with growers to help them troubleshoot and solve different issues. One such issue is properly calculating fertilizer rates. It’s a tedious process that not all growers Denny interacts with want to take the time to do properly.

Denny, recognizing the prevalence of the problem, developed an app called Fertilize It to simplify the calculation process for growers. He had a version he’d used personally and with students, but when Fertilize It was released near the end of 2017, it was the first time the app was made available to the public.

Those interested can find the app at webapps.msucares.com/fertilizeit. Below, Denny answers questions about the app, how to properly measure fertilizer levels and more.

Greenhouse Management: How did you determine that there was a need for an app like Fertilize It?

Dr. Geoffrey Denny: The first thing was I looked around to see if somebody else had something like this that was just online. There was something similar, but it wasn’t quite what I was after I essentially took the formulas that we used and put them into an Excel spreadsheet. What you’re actually looking at on [the app] is an Excel spreadsheet that you put your numbers into and it spits the answer back out.

Dr. Geoffrey Denny
Photo courtesy of Dr. Geoffrey Denny

GM: What are some of the disadvantages to not properly calculating fertilizer injectors?

GD: Most growers are going to be concerned with an increase in their fertilizer bill. If they’re over injecting, [but] they think they’re injecting the right amount, they’re going to end up with an increase in how much they spend on fertilizer every year and probably not going to see a huge increase in plant growth. So, there’s that. And if you know you’re way off, it’s better than not knowing. There’s definitely the potential to cause damage to plants, but the likelihood of that isn’t very high.

GM: What tips do you have for growers for using, or purchasing, fertilizer injectors?

GD: Don’t cheap out and buy the smallest one you can get and then try to run it at a volume higher than that. That’s really going to affect the reliability of it and whether it’s going to be accurate and evenly distributed. Make sure that you actually look at the specs and size up the system correctly. Keep them maintained, too. Also, when you’re running salty water through these things, they tend to corrode if you don’t flush them out. Clean some of the salts out and that can also affect your accuracy. Also, note that the plastics they are [made from] don’t hold up with a lot of the abrasive things that you might introduce [into the greenhouse] and that’s going to dramatically shorten the lifespan of your injectors.

GM: Has creating Fertilize It given you any ideas for other apps growers might want to use?

GD: [Fertilize It] is not going to calculate pesticide rates and it doesn’t have many bells and whistles so that it doesn’t get too complex. It’s intended to do one job and do that kind of easily. So, based on the feedback we’ve gotten, we’re in the process of trying to build [a similar type of app] that will be for pesticide calculation and for broadcast fertilizer calculations and some of those other things that are not difficult tasks, but that are just tedious [for growers].