On hydroponics: picking the brain of Dr. Merle Jensen

On hydroponics: picking the brain of Dr. Merle Jensen

The University of Arizona professor emeritus and soilless-growing pioneer shares a bit of hydroponic history and previews his presentation at Indoor AgCon Las Vegas.

March 31, 2016

Produce Grower: Dr. Jensen, you’ve been known as a pioneer in soilless growing. Can you tell us a little about your background?

Merle Jensen: I worked at the [University of Arizona] 38 years, and took these [soilless] systems to countries throughout the world, approaching roughly almost 60 countries. I can say, quite frankly, that as we know hydroponic systems today, or soilless systems—I started that first at Rutgers University. And then when I came to Arizona we really advanced those systems so that they’re used around the world. It was slow getting started.

In those days, we had everyone growing in soil, but they were steaming the soils or using fumigants, and those two ways of controlling diseases were going down only no more than 18 inches. And so the roots were growing back into the old problems. And so when I went to school at Rutgers [University], I was told that I was going to have to grow in soil. And I said, ‘If I have to steam soil, I’m out of here. I’m headed to California.’ They said, OK, you can go ahead with the soilless troughs that you learned about when you were going to Cornell University.’
I could tell you that we broke records in yields. The yields at that time were 50, 60 tons for tomatoes per acre in one year, and in three months I had 100 tons [the average soil-grown yield]. So that made headlines, and that’s what really got the whole thing going on soilless culture, hydroponics.
I ended up being taking a lot of what I developed into a Disney show called Epcot. I was the senior designer of the agriculture show [within Epcot in Orlando, Fla.’s Walt Disney World] called The Land Pavilion. And we did that starting in 1975. We opened in 1982 and my colleague said, ‘Who in the world is going to go see agriculture? We’ve been to Iowa and we’ve seen corn.’ I said, ‘Don’t worry. We’ll make it dance.’
Well, we’ve had 135 million people through that show since 1982, and I worked with developing those systems, transferred the technology from the university to Orlando, Fla., and for a long time, we were having 35,000 people a day coming through that show. That way was probably one of the best ways that we sort of broadcast new technologies for the future by having millions of people coming through seeing what the future might look like.
PG: What have been some of the biggest advancements — or pitfalls — of what you’ve seen in greenhouse edible production in recent years?
MJ: The biggest advancement is the production systems themselves. Basically, we’ve got the nutrient film technique (NFT), we’ve got the deep flow hydroponic systems. I think right around the corner we’re going to be getting into robotics. … So a lot of these systems require a great deal of labor. In fact, in growing in greenhouses with hydroponic systems, the labor cost can be up 50, 60 percent. So I see that we’re going to work on ways to automate the systems more and get those labor costs down.
We see systems being developed and have been developed in Finland, Spain, in the Netherlands — and while they’re expensive, I think in the long run, cost will come down as we better understand those systems. … That would be mainly for salad crops or leafy greens or herbs, and so forth.
Now, growing greenhouse tomatoes or crops that grow up to 10, 12 feet high on an overhead wire, I think we’ve done a lot of work to conserve energy in those greenhouses by having blankets, and better understanding the systems [through] which we get the irrigation water and mineral nutrition. I think we’ve got that down pretty good.
PG: Can you give us a brief preview of what you’ll be presenting at Indoor AgCon in Las Vegas?
MJ: What I’m going to do is go back and remind people, with a little history, how we got going in soilless culture, controlled environment agriculture, where we are today in growing crops in greenhouses, and how that’s sort of now evolving.
Some people are getting very close to getting it figured out regarding the lighting systems, whether they’re LEDs or other, older sources of light. But the thing is that they are challenged with the cost of electricity — a lot of electricity — and is this going to replace what we do in greenhouses? Or is this indeed the future? I think the question is that’s still up in the air … It may be that vertical farming, or enclosed farming, will be in areas in certain cities where people can afford the prices that are needed for their products so that these growing systems are affordable. 
This interview has been edited for length, flow and accuracy.