Growing Mineral Rich Food – Are Heirlooms and Organic Methods Better?

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Robert Pavlis

Everybody wants to grow nutrient dense food that is more nutritious, but what methods produce the best food? There is lots of talk online about organic gardening producing healthier food but is that really true? Are heirloom varieties better for you than hybrids?

In this post I’ll look at some interesting studies that try to answer these questions and the answers will surprise you.

Growing Mineral Rich Food - Are Heirlooms and Organic Methods Better?
Growing Mineral Rich Food – Are Heirlooms and Organic Methods Better?

What is Mineral Rich Food?

A number of terms are floated around in discussions about food quality. A very popular one is “nutrient density”. I have discussed nutrient density is some detail in a previous post; The Myth of Growing High Nutrient Density Food. The term is so poorly defined that it does not mean much.

Another term that is very ambiguous is “healthier” food. That can mean many things. Does it mean more nutritious? Or maybe it contains fewer toxins? Discussions that use this term, without a clear definition, are mostly useless.

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In this post I am using the term mineral rich to mean food that has higher levels of basic minerals including phosphorus, potassium, calcium, magnesium, sodium, zinc, boron, manganese, copper, iron, and molybdenum. These are all minerals the body needs, so food with higher levels are healthier, provided they don’t reach toxic levels.

How do you grow mineral rich food?

Growing Mineral Rich Food Studies

I’ll have a closer look at two studies carried out by Allen Barker and his team, using tomatoes and cabbage, in multi-year field trials. I’ll also have a quick look at their study on lettuce.

The studies compared numerous cultivars of each vegetable and categorized them as either heirlooms (prior to 1950) or modern. In the case of cabbage, all moderns were F1 hybrids.

Three different fertilizer regimes were used; synthetic chemicals (10-4.4-8.3), organic with the same NPK (soybean meal, bone meal, and K2SO4) and compost. The synthetic and organic fertilizer provided 84–37–60 kg N–P–K/ha at planting and the compost provided about 280-60-40 kg/ha. The compost was made from cattle manure and crop residues.

The food produced was analyzed for mineral content, size and yield.

Heirloom vs Modern Varieties

Tomatoes:

On average, modern varieties produced a higher yield than heirlooms. But out of the top 6 producers, half were moderns and half were heirlooms.

Moderns also had larger fruit, but select heirlooms did produce the largest fruits.

Selecting the right cultivars is more important than selecting between modern or heirloom.

Cabbage:

Modern varieties produced higher yields than heirlooms.

Yield Based on Different Fertilizer Regimes

Tomatoes:

Fertilizer regime had little effect on yield or fruit size.

Cabbage:

Head weights with chemical or organic fertilizer were the same, but compost produced heads that were 72% smaller. This smaller size was probably due to lower levels of plant-available nitrogen.

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Mineral Concentrations

Tomatoes:

It is a common belief that the smaller size of heirloom fruit means they contain higher levels of nutrients or worded another way, large fruit contains excess water which dilutes the minerals. On a weight basis, the minerals in modern and heirloom fruit were about the same. Larger fruit does not result in diluted nutrients.

Small fruit and large fruit contain similar amounts of nutrients on a weight basis. So it does not matter which size you eat; it’s the total amount of tomatoes that is important.

Fertilizer regimes had little effect on either macro or micro nutrients. The small variations that were observed would have no impact on diets.

“Differences among individual cultivars for each element were large. Cultivars with the highest accumulation of nutrients had about 20%–50% more of each nutrient than cultivars with the
lowest concentrations, with the exception of Fe, which was 100% higher. Considerable consistency occurred among cultivars that were the top accumulators of nutrients, but no cultivar ranked in the top five positions for all elements in each year.” What this means is that no single cultivar is the “most nutritious”, but some cultivars are better than others.

This study also looked at Brix values and confirms my previous conclusions, that Brix readings are not useful for measuring mineral concentrations.

micronutrients in tomato cultivars, study by Barker et al
micronutrients in tomato cultivars, study by Barker et al

Cabbage:

Heirlooms and moderns had the same level of minerals. Larger heads did not dilute the minerals.

The fertilizer regime had no, or very little effect on mineral nutrient levels. Synthetic and organic fertilizer did produce higher yields.

The cabbage cultivars being tested had various maturity dates, but this had little effect on nutrient concentrations. Slow growing cultivars did not have increased nutrient levels.

Except for iron, the variation of nutrients in different cultivars was not dramatic.

The concentration of minerals in cabbage are considerably lower than in lettuce and it has been suggested that the closed heads of cabbage may limit nutrient absorption in the heads.

Micronutrients in various cultivars of cabbage, study by Barker et al
Micronutrients in various cultivars of cabbage, study by Barker et al

Minerals in Lettuce

Similar studies have been done on lettuce. Modern and heirloom selection had very little effect on mineral concentrations in lettuce. Yields were higher with synthetic and organic fertilizer, than with compost.

Conventional Agriculture vs Organic Agriculture

A meta-analysis of the yield performance of organic and conventional agriculture found that organic results in 5 – 35% lower yields. The above studies on cabbage and lettuce showed similar results when compost was used as a fertilizer.

This is one of the reasons scientists are skeptical that organic farming could feed the world.

What Does It Mean For the Gardener

Mineral nutrition in tomatoes is dependent on cultivar selection. Heirlooms and moderns are equally nutritious and the fertilizer regime has little impact. Organic fertilizer is not any better than synthetic, in this regard.

Similar results were found for cabbage. Heirlooms and moderns produce similar results and the type of fertilization has no effect on mineral content, provided enough nutrients are provided to the plant.

These results will be surprising to many because there is so much misinformation floating around about the benefits of heirlooms and organic gardening techniques. But consider this, heirlooms have been selected by gardeners mostly for flavor, and freedom from pests and diseases. How many gardeners analyze the mineral content of the fruit they select for seed harvesting? Not many. So it should be no surprise that heirlooms have not been selected for high nutrition.

Should modern day hybrids be more nutritious? Their development is focused on commercial needs such as shipping quality. There has been very little attention paid to nutrition.

As far as organic fertilizer goes, it all has to be decomposed into nutrient ions before plants can use it. Once in that form, the nutrients ions are identical to the ones found in synthetic fertilizer. The idea that the two are different, as far as fertilizing plants goes, has never made any sense to those who understand some basic chemistry.

Should you select cultivars for their higher mineral content? That depends on where you live. In countries that have access to lots of food, it really is not an issue. Select for taste and easy growing characteristics. If nutrition is an issue, then try some of the more nutritious cultivars, but keep in mind that switching from cabbage to lettuce may provide you with more mineral nutrients than trying to find the most nutritious cabbage.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

18 thoughts on “Growing Mineral Rich Food – Are Heirlooms and Organic Methods Better?”

  1. I also wonder what water was used distilled filtered reverse osmosis berkey mountain spring or TAP !
    Maybe Zamzam or Knock water lol

    You can taste the slight sea salt in unsalted Normandy butter because the cows eat grass that grows at the seaside the same applies to food grown near the sea

    Water is way more important than soil

    Reply
  2. Classic straw man argument.
    I love articles like this one. It convinces the dumbbells out there (with “scientific evidence” ) that there isn’t any difference between homegrown,heirloom varieties and hybrid plastic tasting food from the store. Hey say the scientists, we measured all the nutrients with our super duper technology and they are exactly the same, don’t trust your taste buds, they are deceiving you, keep buying the plastic food that our masters from Big Ag are providing for you at a very low cost.
    Meanwhile, the Queen of England is 95 year old, has eaten organic, heirloom vegetables from her own gardens all her life and has never been to a conventional doctor…while the all knowing doctors and “scientists” have the shortest lifespans among all professions and are constantly plagued by “viruses” and diseases. They surely know better though, after all they have some very fancy diplomas hanging on their walls and even …..gasp……the latest model microscopes and gas chromatographs .

    O tempora, o mores!

    More organic, heirloom vegetables for me and mine, I simply love it.
    Thank you, “scientists” !!!

    Reply
    • The testing by scientists was done by using taste tests – so average people decide on tests, and by using standard lab tests – which is the way you determine say the vitamin content in food.

      What you don’t do is ask the Queen what she ate!

      Clearly not everyone believes in science.

      Reply
  3. I had to laugh when I started reading this, my thought was how many of us open up our seed catalogs in January and think, “Hmmm, I wonder which one of these cultivars is the most nutritious!” (No one.) And yet the internet is flooded with this heirloom vs. hybrids, organic vs. non-organic debate.

    Just grow something that’s going to make you smile, and happy when you eat it. Done. Mission accomplished.

    Reply
  4. I see nothing about the history or quality of the soils used in these studies. I would think that what you start with has at least as much impact as the current year treatments.

    Reply
    • Soil and weather will certainly affect the absolute numbers, but since controls are being used it would expect the conclusions.

      The best performing cultivars could be different in other conditions.

      Reply
      • It seems to me that for the organic vs. conventional debate, the interesting question is whether or not years of organic practice build a soil which leads to more nutrient dense food – through biology, organic matter buildup, improvement in structure, etc. I realize there are many different organic practices, but the question here – whether or not one year’s difference between compost and synthetic fertilizer will be noticeable – does not seem very interesting.

        Reply
        • Organic gardening is mostly about using a different class of chemicals. This has little long term effect on soil, so it would have little effect on nutrition.

          Farming in such a way that soil is improved – eg no till, does build up organic matter in soil, and may lead to higher nutrition. But that is not a organic vs conventional debate. It is a conventional vs new technique debate. You can easily use no-till and synthetic chemicals and see improvement in soil. Use of more cover crops + synthetic fertilizer does the same thing.

          Reply
          • You do not mention the environmental costs of synthetic nitrogen use. It is my understanding that synthetic N sources contribute to soil acidification, are easily leached from the soil, and have a very high energy cost to produce, and can also contribute nitrous oxide to the atmosphere, a very potent greenhouse gas and a contributor to ozone depletion. We may not generally associate environmental costs to nutrient density in food, but environmental costs are associated with every choice we make, in the garden or otherwise.

          • This post was not intended to look at other aspects.

            Some of the things you say are correct, but they also apply to organic sources of nitrogen. Both leach easily from soil, the nitrate form acidifies soil, urea and ammonium do the opposite. Both are converted by microbes into nitrous oxide – a significant amount is lost during composting.

            Making synthetic nitrogen does require energy, but once it is made, it has a much lower transportation environmental-cost than organic sources because it is more concentrated.

  5. This is good information to know. I’d like to know just what these most nutritious cultivars are. If you know them, please share.

    Reply
  6. Whilst I found this interesting, I question how much help it is to the average gardener and how frustrating it is for a tomato obsessive like me. living in Melbourne, Australia where all but a few of the varieties are new to me. I also don’t know which are heirlooms. Did I miss that somewhere? What role if any, does weather play? Our just concluded summer was cool and inconsistent with less rain than the average. The result has been very slow ripening but interestingly, the best looking fruit I can remember. Good yields on some varieties, much less on others. And then there are variances from bed to bed, perhaps depending on how long the bed has been established and where it is located in terms of hours of sun. And then there is a big variation in individual beds. One variety going gangbusters and a metre away another variety under achieving, Of the approx 35 varieties, almost all heirlooms, most have been grown each season for at least 4 years and all have at one time or another been good producers or I would not have persisted with them. And the positions in which I grow them are random every year.
    My unscientific conclusion is that rules, research and recommendations by experts are close to meaningless. Would this experiment, if carried out elsewhere in differing types of soil and weather, yielded significantly different results?
    Having said that, I would still love to be able to go to a data base and see the results for the varieties I grow!

    Reply
    • Will different weather and soil affect results? Possibly. But since they looked at quite a few cultivars, I doubt it. The actual numbers and the ranking of cultivar would change, but I don’t think the overall conclusions would. For example, why would heirlooms do much better than moderns in one soil compared to another? If the study only looked at a couple of cultivars – that would be a much larger possibility.

      Reply
  7. It looks like a comparison across flavour, food “value” and the absence of “polutants” – I use the inverted commas to suggest broad, not narrow, definitions. My sense of the benefit attaching to heirloom plants is that it relates to flavour and feel. Many “modern” plants produce fruit that is large, rather than flavoursome, and denser/more robust. The latter because the issue is getting the product to market, surviving both the picking, packing and transport processes and then delivering shelf life to the benefit of the retailer – I avoid trying to think of the waste that must be associated with being a greengrocer and the effect that has in over-production and on prices.
    The home gardner is spared these commercially related concerns and can focus on quality rather than quantity and the characteristics that get product to the table. The constant commercially driven concerns have given us fruit, for example, that looks ripe, but isn’t; that looks like it should taste great but doesn’t; and that “ripens” on the kitchen bench by slowly rotting. To boot, we have lost varieties, like the Wigan peach here in Australia because it doesn’t “carry” well and lacks extended shelf life.
    The organic “industry” has other fish to fry around nutrition and the absence of chemicals, matters that home gardeners are able to address reasonably effectively.

    Reply
  8. I wonder if highly developed fruits and vegetables may be less nutritious. eg mangoes have been selected for their sweetness, flavour and size for thousands of years. At least the high sugar dose isn’t very healthy compared to the fruit’s primitive ancestors. But in most cases the primitive ancestor no longer exists for us to analyse and compare.

    Do we have any information about vitamin or other nutrient content?

    Reply

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