Differences of Organic vs Conventional Crops w/ Gene Lester

Interview with Gene Lester, National Program Leader at USDA-ARS

Show Notes

What really differentiates organic crops from conventionally grown crops? To find out, we welcome Dr. Gene Lester, National Program Leader for the USDA’s Agricultural Research Service. Dr. Lester has years of experience researching various attributes of organic versus conventionally grown fruits and vegetables, including quality differences for marketability and nutrition.

Learn more about USDA-ARS: www.ars.usda.gov 

Connect with our guest on LinkedIn


Podcast Transcription

TOM: This week, I interviewed Dr. Gene Lester. Dr. Lester is a National Program Leader for USDA’s Agricultural Research Service. Dr. Lester researched the attributes of organic versus conventionally grown fruits and vegetables, including the quality differences for both marketability and nutrition. Listen to the full episode to understand what differentiates organically grown crops from conventionally grown crops.

INTRO: Welcome to Organics Unpacked, a podcast for the business-minded organic grower — an interview podcast where we hear from the top experts in the commercial organic industry — with a focus on the business elements of organic growing both in and out of the field. You will gain insight and grow your operation. This show is brought to you ad-free by Avé Organics, a Wilbur-Ellis company. To learn more about Avé Organics, visit our program notes. In the meantime, enjoy the show.

TOM: Hello, everyone. Thanks for tuning in today. Welcome to a new episode of Organics Unpacked, a podcast where we discuss organic farming from a practical view. I’m your host, Tom Buman. Today, I’m joined by Dr. Gene Lester. Dr. Lester is a National Program Leader for USDA’s Agricultural Research Service, or ARS. In a past position, Dr. Lester was acting National Program Leader, overseeing organic farming. Gene, welcome to Organics Unpacked.

GENE: Thank you, Tom. Happy to be here.

Working with the Agricultural Research Service

TOM: Well, it’s really good to have you. I know that you have had a lot of background working with organic farming, and so it’s great to have your expertise and the expertise of USDA’s Agricultural Research Service. Before we get started, though, tell me about your background. How did you get to the position that you’re in today?

GENE: Okay, so I’ve been with the Agricultural Research Service — this year now — 37 years, and I started as a research scientist in post-harvest quality and preservation. In doing that research, that originally started in Texas and is part of the reason I was able to work on conventional versus organic-produced Ruby Red grapefruit. Soon after that research was published, I was asked to come to the flagship of the Agricultural Research Service, which is in Beltsville, Maryland, and continue my research there. While I was in Beltsville, Maryland, just across the street was the headquarters to the Agricultural Research Service — the Office of National Programs — and they asked me to come and do a detail because the National Program Leader had retired. And I did, apparently, such a good job they asked me to stay. So I had to give up my research about 12 years ago.

Food Attributes of Organic vs. Conventional Farming

TOM: Okay. Well, that’s a really in-depth background, as far as what you’ve done with organic farming. I know that you’ve done work, and so we want to talk about the work that you did as a scientist with ARS. And I know it largely revolved around comparing some food attributes of organic farming versus more conventional farming. So, like in fruits and vegetables, maybe the taste and texture and a few things like that? Is that correct?

GENE: That’s correct, and so that was my area of research. I conducted taste panels and was charged by the Agricultural Research Service to look at quality differences — not just marketable quality differences, but nutritional quality differences in fruits and vegetables. The crop that I was primarily in charge of was cucurbits, primarily: honeydew melon, cantaloupe melon and those fruits. But fortunately, where I lived in the Lower Rio Grande Valley, grapefruit was a major crop. And I had, in my talking to farmers and what have you, realized there was a large conventional and organic grapefruit production system in the Lower Rio Grande Valley, Texas. So I availed myself of that study, simply because the USDA was just now developing the National Organic Standards and where the USDA was now taking charge of what was organic or not organic to be sold in the marketplace.

Controlling the Variables

TOM: So, Gene, I often hear the two sides of the story: that organic foods taste better, better quality. I hear the same thing with conventional. So your research: what did you find? Well, first off, maybe talk a little bit about the integrity of your research. I know that it’s kind of easy to take an organic apple and a conventional apple out of the grocery store — taste one and taste the other — but you have, really, no idea if they controlled variables or if they were grown in the same place. Talk a little bit about how you set up your research, and then we can talk a little bit about maybe the results that you found. 

GENE: Exactly, and what you’re describing was an awful lot of the early studies in the comparison of the two production systems, where researchers — I’m not going to say any. I’m not addressing fault, but it made sense. Okay, I’m going to go into the grocery store. This is a real-life situation because this is what consumers are going to be up against. You’ve got a bin of organic apples and a bin of conventionally grown apples, and you pick up the two. And you do a taste panel, and you compare the two. Well, the problem is that’s just not a legitimate comparison system. We found that, say, if you grow carrots — you’ve got two different cultivars of carrots or two different types — and you grow them in two different locations, the cultivar and the location effect is going to have a much greater impact than the sensory quality attributes. So one has to do an extremely controlled study, and I found that in the grapefruit situation, this was perfectly set up. And where this was: about 14 years before, we had a major freeze in the Lower Rio Grande Valley, which basically wiped out the fruit tree industry. So I was able to deal with organic grapefruit and conventional grapefruit that were of the same age, the same size. They were grown on the same soil type. They had the same micro in climate — microenvironment — meaning that they were separated by just enough that the National Organic Standards said that a conventional and an organic orchard had to be separated. The irrigation source was the same. We harvested the trees at the same time: 10 o’clock in the morning. We harvested the same canopy location. Then, we also made sure that the fruits were of the same uniform size, fit within a marketable size and free of defects. And we also replicated what the industry did. We harvested in the early, mid and late-harvest season. And for grapefruit in the Lower Rio Grande Valley, that’s the 1st of November for early, the 1st of January for mid and the 1st of March for late-season harvest of grapefruit. Just having those different harvest times had a dramatic impact, as well.

TOM: In keeping with USDA’s Agricultural Research Service, you certainly controlled for the variables. It sounds like really good research.

GENE: Exactly, and that’s what you have to do. Or otherwise you’re going to confound, then, the impact of the organic production inputs and the conventional production inputs. So, with all of those variables that aren’t production input-based but are just common variables across Ruby Red grapefruit, they were equally paired. So anything else could be zeroed out, and then we could focus completely on organic versus conventional inputs.

Organic vs. Conventional Ruby Red Grapefruits

TOM: Okay, so we’re working with Ruby Red grapefruits. What kind of attributes did you want to compare in these grapefruits between organic and conventional?

GENE: Well, we compared three major areas. The first is the market quality. And if you want, after I introduce the other two, I can go in and give you just some interesting comparison differences. So we did market quality, both of the whole fruit and of the juice. Then, we did human health compounds like minerals, ascorbic acid and lycopene, which is what gives Ruby Red grapefruit its color. Then, we did some drug interactive compounds because grapefruit, as you know, it has been said: do not consume grapefruit juice with cholesterol-lowering drugs and psychiatric drugs because the furanocoumarins, which is a big word, are interactive with these drugs and give you heightened effects. Now, I’m not a doctor, so I’m not going to say that’s good or bad, but I can say it gives you heightened effects.

TOM: Okay, all right. So, when you compare those attributes, did you find it was all one way or another? Like all good in one — like maybe organic or conventional — and all bad in the other? Or was it kind of a cross mix of different things?

GENE: Well, just a big overview, and I’ll give this when I talk about fruit weight: what we basically found was because — and then the other thing we paired for is that — the actual amount of nitrogen applied to both systems was identical, the actual amount of phosphorus and potassium that was applied in both systems was identical. The only difference was that in the organic, the fertilizer was applied as compost and fish emulsions, whereas in the conventional, it was synthetic fertilizers. And where we see the differences is that it’s basically a slowly available nutrient system to the organic production versus an immediate nutrient-available system to the conventional, and that was easily seen when we just looked at fruit weight itself. So the study was done — like I said, we harvested early, mid and late season — and we did that consecutively for three years in a row so that we didn’t have any year effects because, some years, you can have a high and then low. So we did it over three, so we were able to zero it out. So all of the data that I’m going to give you are going to be averaged over the three-year period of time. And in the early-season grapefruit — and I’m going to give you as grams — now, remember: 454 grams is a pound. So the conventional grapefruit in the early season was 470 grams, whereas the organic grapefruit was 400 grams. Then, as we moved to mid-season, the organic grapefruit became 450 grams, and the conventional was still about 470. Then, by late season, which was March, there was no difference in the fruit weight. So you can see that a slow availability of the nitrogen and the nutrients taken up through the organic production system gave you some fruit quality factors at the end of the system, which allowed it to catch up to the early-season fruit. So, by not doing the early, mid and late season, we wouldn’t have been able to tease out that difference between organic and conventional productions.

Nitrogen Availability in Organic Farming

TOM: Right. So, in the weight of the grapefruits, it largely came down to nitrogen availability, if I’m correct, right?

GENE: You’re correct.

TOM: In organic farming, you apply it as compost. In some other products, it took a while for the nitrogen to become available, and that held back the weight of the fruit a little bit, correct?

GENE: It held back the weight of the fruit, and it held back some of the ripening attributes that impacted market quality and human health compounds.

TOM: Okay, and so what about those things was a significant difference between the two?

GENE: So, in the market quality area — I already discussed the fruit weight — we found that the specific gravity, basically, was higher. So that has to deal with just the dry weight. It was basically higher in the organic system than the conventional system. The peel thickness was also much thinner in the organic system than the conventional. And from an agricultural marketing service, which regulates the market quality of fruits and vegetables, a thin peel is markedly more advantageous and gives you a higher-quality fruit than a thicker peel when I’m talking about citrus. Because when you pick up a thin-peeled grapefruit, lemon or lime or mandarin or orange, it tends to be more pliable and tends to be, seemingly, more juicy. So it’s a beneficial thing. The other thing is the color. Now, the conventional grapefruit was brighter and less dark — and just stick with me on this — and it had greater color intensity. And the color was: on the outside of the fruit, the grapefruit in the conventional system was a brighter, more vibrant yellow, whereas, in the organic system, it was more green. So it was darker and less vibrant, and it wasn’t ripening up at the same rate as the conventional because of the slower or lower availability of nitrogen in the organic.

TOM: Okay, so that obviously impacts the consumer when they go to the store, and it’s not the same color. It doesn’t mean that the taste is different or not, but a lot of food is chosen based on just appearance, right?

GENE: Oh, absolutely. Uniformly yellow. It appears riper. It’s brighter. It’s just more appealing.

Planning for Nitrogen Deficiency

TOM: Right. So, when you think about that, were there ways that you could help organic farmers plan for that nitrogen deficiency early in the season? Were there things that came out of the study that kind of helped, maybe, think about the nitrogen a little differently?

GENE: Well, exactly. So, with that in mind, especially in an orchard system like grapefruit, where you’re going to pick multiple times over the season, that’s where I think — now having this sound scientific knowledge and finding, which anyone can refer to this paper — can we go about developing in the organic production system so that there’s more available nitrogen readily available, right at the beginning of each production, whether it’s one-harvest peppers, for an example, or a multiple-harvest orchard system? That, I think, will help answer the question. And where I want to be able to address that even more is as we can see some interesting nitrogen-dependent aspects with regards to human health compounds that I can talk about a little bit and, particularly, the furanocoumarins, which are definitely nitrogen dependent.

Meta-Analysis of Organic vs. Conventional Systems

TOM: So, Gene, before we kind of get into that — because I definitely want to do this — you started your research with grapefruits. How have you kind of looked at the larger fruits and vegetable world in this organic versus non-organic? Let’s talk about more than just grapefruit because I know that you’ve done some work in other things too.

GENE: Okay, so, then, after the grapefruit study, we did a meta-analysis study, whereas we went in and did an overwhelming research of the literature and because, fortunately, in Beltsville, Maryland, the National Agricultural Library is just across the street. So I was able to go work with the librarians, and we could do an extensive search of the library collection that we have, where we could say we wanted organic versus conventional production systems. But we wanted to make sure that, in their materials and methods, everything that I addressed early in our conversation in the non-organic and the non-conventional input parts were as well matched as possible. So, in this meta-analysis, we found that organic crops tend to have significantly higher vitamin C, have significantly higher sugars and significantly higher phenolics and significantly lower nitrates. And that’s all nitrogen-based because vitamin C is basically the result of sugars, which is glucose, which is converted to vitamin C. So, if you have high levels of sugar in an organic system, because there isn’t nitrogen there to move the sugars to other nutrient components, you now have a large base to produce a lot of vitamin C. You also have a large number of phenolics, and phenolics are bitter-tasting compounds. 

We found that, in a comparison study, in a greenhouse study, where they were able to control for disease and able to control for insects — because everyone said the reason you’ve got higher phenolics in organics than conventional is because you don’t have pesticides on there controlling for insects and disease — well, in an organic system, in a greenhouse production facility, where you had no such disease and no insects, the organic production system had higher levels of phenolics. And phenolics are bitter-tasting compounds, and that’s why insects don’t like it. Then, because you don’t have the high nitrogen there, you don’t have nitrates, which are not beneficial to your health. So, also, you tend to have, in an organic system, a little higher soluble solids, a little less protein — unfortunately, a little less yield — and a little less weight because of water. But you do have more beta-carotene because that’s just a sugar base. But in the grapefruit, you don’t have high lycopene because it’s nitrogen that takes the sugars that make the lycopene. And as a result of having more phenolics in an organic production system, you have more antioxidants, which are, we know, very beneficial for fighting a lot of diseases in our system. And in a kiwi study, you had 15% more antioxidants in organic kiwis than conventional. And in a green pepper study, you had 25% more antioxidants in an organic than a conventional production system.

Impacts of Nitrogen Availability on Food Attributes

TOM: Does this all come down? So it sounds like it’s a mixed bag: some good, some bad created with that early nitrogen deficiency?

GENE: Yeah. 

TOM: Does it all come down to nitrogen, and available nitrogen causes some good things to happen and maybe some not-so-good things to happen?

GENE: Well, remember: they’re all good to the plant. It’s just that we may not find them good for us because of our consumption of them and how our body, then, reacts to these compounds.

TOM: All right, so it’s these attributes. Some of them cross into different fruits and vegetables. I suppose some of them are specific to certain fruits and vegetables, but what you find is that it’s pretty much a mixed bag.

GENE: Yeah, and many of the studies that have shown that the differences in the nutritional qualities of organic versus conventional fruits and vegetables are very strongly associated with the organic system delivering limited rates of nitrogen.

TOM: Okay. So, if we would make nitrogen more available early in the season, would the two systems look pretty much the same then? Because is it really the nitrogen availability from organic fertilizers that’s kind of making the difference?

GENE: Yeah, and where I can say that is that at the end of our system, like we said, we had early, mid and late. And in the late system, our organic grapefruit, we’re now catching up color-wise and a number of factors-wise to our conventional, synthetic nitrogen production systems.

TOM: Then, were they losing ground in things like antioxidants: the positive attributes that came from maybe a little nitrogen deficiency?

GENE: They were becoming a little more equal, but because they had higher levels early on, during the stressful periods, they just had higher levels already in the fruit.

Factors for Buying Organic or Conventional

TOM: Okay. All right, so there are a lot of things going on there. It’s not as straightforward. Okay. So, as a consumer, when you look at the overall of organic versus conventional, where do you fall? Knowing what you know as a scientist, knowing what you like as a consumer, where do you fall in it?

GENE: Well, I think if your concern is primarily pesticides and a whole other host of factors that you don’t know about, and if that’s of great, great concern to you, then I strongly say: Definitely stick with the organic system.’ Now, it’s also going to have to be, with the organic versus the conventional, if it’s all about presentation on your plate, then sometimes your conventional may just look a lot better to you.

TOM: Okay. All right, so it kind of depends on what your objective is as a consumer. 

GENE: Yeah. 

TOM: All right, so I really appreciate your time today. You shared a lot of good information. Are there other things that farmers and consumers should know about your studies?

GENE: Well, I don’t know if you wanted to get into the human health compounds or the furanocoumarins or not, but we can talk about that. 

Health Effects of Furanocoumarins

TOM: Absolutely.

GENE: So this is pretty much a nitrogen thing. So, of course, when it comes to the minerals, we found that there were higher levels of nitrogen in the conventional versus the organic, significantly higher levels of ascorbic acid in the organic, significantly higher levels of lycopene, which is the red coloration, in the conventional. The sugars were more in the organic, and the pH was higher in the organic. But when you came to look at it, we also did a consumer preference panel that, because of the high ascorbic acid and the high phenolic compounds in the organic, even though you had significantly higher sugars, the organic was perceived as more tart, less sweet and, overall, less accepted than the conventional. 

TOM: Okay.

GENE: So, if you’ve got the organic, and it’s a little more tart and more or less sweet, you can do some blending where you can diminish that, especially if you’re dealing with a commercial juice product. But there are some very good benefits. Because we don’t have the higher available nitrogen early on in the organic system like the conventional system, the conventional had more bergamottin, which is a furanocoumarin that does interact with cholesterol-lowering drugs and psychiatric drugs. And it has more potent dimers of the bergamottin, which are even more potent in interacting with the drugs. The flavonols, unfortunately, are higher in the organic, which can tend to give you a little bit more better principal. So those are some of the things that you need to know about in an organic and a conventional production system, and also less nitrates in an organic system. And nitrates are associated with health effects and, primarily, the blue baby syndrome. So, overall, conventional grapefruit had better uniform lycopene coloration and was less bitter, but the organic had more sugars. It had more ascorbic acid, which is beneficial. It had a thinner peel, which had greater marketability. It had lower drug interaction compounds, and it had lower nitrates. You choose what you want. 

TOM: Right. 

GENE: But it all comes down to nitrogen.

The Future of Organic & Conventional Studies 

TOM: Okay, that’s really interesting. And just the fact that, in an organic system, we have limited nitrogen early on because it’s mineralizing in our organic fertilizers versus, on a conventional, we put on that commercial fertilizer that’s available from day one.

GENE: Yeah. So, in a 10-year study, in a potato study, where they looked at the effects of nitrogen in conventionally and organic-produced potatoes, they found that total nitrogen was significantly higher in the conventionally grown tubers, even though equal amounts of nitrogen were applied in both production systems. And we found the very same thing in the grapefruit study. So, basically from that, it says that the future of organic and conventional studies should not be just limited to measuring produce quality differences, like I gave you a whole laundry list of. But it must focus on soil fertility, plant and root interactions and controlling bacterial and mycotoxin contaminants, especially in the organic produce system. So really getting some soil scientists involved in this, it’s going to be critically important to help us try to equalize these two systems.

TOM: Okay, that’s fascinating. Now, I assume that it depends on the type of fruit and vegetable of what attributes you’re going to enhance or maybe kind of leave behind, right? This is not necessarily universal, that, because this happened in grapefruit, it’s going to happen in kiwifruit or something like that.

GENE: Yep, you’ve got to take it crop by crop.

TOM: Okay, which means a lot of work needs to be done to figure out all these little interactions.

GENE: Right, and I’m not going to go into any details. But in my meta-analysis paper, I looked at minerals, and what was higher in one crop for organic versus conventional was almost the reverse of a completely different crop. And that’s nature. Nature doesn’t perform the same, and we don’t want nature to perform the same because one atmospheric or catastrophic event is going to wipe out our entire plant kingdom. And we certainly don’t want that. So we want all of our plants to perform differently so that there’s some survival here. And it shows that the plants do perform differently in conventional than in organic production systems. I don’t mean to be getting too philosophical here.

TOM: No, that’s perfectly understandable. We need a variety in the plant community, for sure. 

GENE: Yeah. 

How to Decide Between Organic & Conventional

TOM: But I want to be mindful of your time. I really appreciate you taking the time to be with us today.

GENE: Oh my goodness. This went fast.

TOM: I really enjoyed the conversation. It is a debate that’s ongoing, obviously. The last thing I want to ask you is that you have two minutes with a consumer, and they’re trying to decide between organic and conventionally raised and whether organic is worth the extra money. What do you tell them in two minutes to just boil down everything of how they should be thinking about this decision?

GENE: Well, it’s going to have to come down to taste, one. And if you see that if the organic tastes better, then fine. If the conventional tastes better, fine. I’m not here to promote one system over the other. What I’m here to promote is, in general, we do not eat enough fruits and vegetables in this country. And if you’re going to say, I’m going to do conventional,’ and that allows you to eat fruits and vegetables, go forward. I’m just saying: Eat your fruits and vegetables.’ And if you like the organic over the conventional, then eat the organic, please.

TOM: All right, that makes really good sense. So, with that, thanks to our listening audience for tuning into another episode of Organics Unpacked. Please tune in for another episode in the near future. Thank you very much to Dr. Gene Lester, Program Leader of USDA’s Agricultural Research Service.

GENE: And thank you for inviting me. I appreciated the opportunity. 

OUTRO: Thank you for listening to Organics Unpacked. If you enjoyed this episode, please consider subscribing and giving this show a five-star rating and review, so we can continue to help organic growers improve their operations.