The Detroit Garden Center:  Feature Articles

If you've considered going organic for the produce you buy, or even grow yourself, you may wonder how organically-grown and conventionally-grown foods stack up in terms of nutritional value. For some time, organic foods have been promoted as healthier simply because they don't contain potential toxins from the chemical fertilizers and pesticides in general use.

There is also a way to measure their relative nutritional value, and the news is good: Organically grown foods are not only less likely to contain toxins and carcinogens; they are also generally more nutritious and the means for growing them make for more sustainable agricultural methods over the long term.

Brix

Wine makers have long relied on something referred to as the "specific gravity" of the fruits they use in their business to determine readiness for harvest and transformation into a fine wine. Grapes are measured, using a device called a refractometer, to determine the quantity of solids in solution and their sugar content and, therefore, their value in contributing to a quality vintage. This measurement of a fruit or vegetable's specific gravity is referred to as "Brix." By taking a small portion of the fruit or vegetable and putting it through a garlic press to extract its sap and coating a lens on the refractometer with it, a reading can indicate that fruit or vegetable's Brix. The reasoning is that the higher the specific gravity, or Brix, the higher the sugar content and, as sugar molecules carry nutrients in solution, the higher the overall nutritional value of the fruit or vegetable.

Numerous charts have been developed reflecting the relative Brix values of organic and nonorganic fruits and vegetables. Consistently, organically-grown produce registers a higher Brix reading. The Brix level of onions ranges from 4 (poor) to 13 (excellent). Therefore, high-quality onions have more than three times the quantity of dissolved solids; apples have three times (18 : 6), potatoes have over two times (7 : 3), and tomatoes more than four times (18 : 4).

Obviously, if a given quantity has more nutrients in it, you don't need to eat as much in order to get those nutrients. For example, four ounces of home-grown potatoes are just as filling as a larger quantity of conventionally grown potatoes you purchased at your local grocery store. This fact is born out in dairy cattle: those grazing on higher-Brix alfalfa; and a 50% increase in alfalfa's Brix level can increase milk yields 10 to 12 percent.

High-Brix plants are also more resistant to insect pests and plant diseases. In fact, high-Brix plants are generally hardier, even surviving frost better because of their higher sugar content. It is well documented that insects and diseases tend to gravitate to weaker plants, while healthier plants generally repel such pathogens. The exact reasons for this are unclear, whether the plant "broadcast" its status for prospective pests or more robust plants are simply harder to eat.

One measurable characteristic that distinguishes healthy plants from relatively unhealthy ones is their relative Brix levels. Peter Bray, a long-time advocate of organic gardening shared the benefits of his experience with local gardeners, members of the Master Gardeners of Greater Detroit last September.

Inviting attendees to bring their own home-grown (or store-bought) organic (or otherwise) fruits and vegetables, Mr. Bray helped everyone to see the technique in action, from preparing the sample to making and compiling readings. Organically-grown samples consistently attained higher Brix ratings than non-organic samples.

How to Improve Your Brix

Mr. Bray also shared some techniques to improve the Brix for home-grown produce. Although some adherents suggest the simple application of an organic source of sugar (such as organically-made molasses) is the answer, on the theory that it would increase sugar and, therefore, nutritional content, the equation is not so simple. Rather, it is by following the tenants of organic gardening - use of organic soil amendments and techniques instead of "quick-fixes."

First of all, by boosting soil humus and continuing to increase it aids in growing high-Brix plants. Soil is supposed to be (at least) five percent organic matter. If five percent organic matter in your soil is good, ten percent is even better, if you're trying to grow highly-nutritious, organic produce.

By increasing organic matter in the soil, the biological activity in the soil is increased as well, which also increases the amounts of mineral nutrients available to your plants. Magnesium, phosphorus, calcium and boron all contribute to the production and transportation of plant sugars. Avoid using herbicides and artificial nitrogen fertilizer both of which inhibit biological activity in the soil. Herbicides may or may not kill weeds, but they definitely kill soil bacteria indiscriminately. Application of artificial nitrogen results in lush, green plants, but it also uses up soil humus more quickly than it can be replaced. If additional nitrogen is needed in the soil, add it by growing legumes in your plant rotation rather than applying artificially-produced nitrogen. Third, and finally, balance the minerals in the soil. This means soil testing. Correct any mineral deficiencies revealed by soil tests and avoid creating excesses, which are much more difficult to correct. If mineral deficiencies are corrected according to recommendations on the soil test, it is more likely the different minerals will come into better balance with one another. This is important because a proper balance of soil minerals is required for efficient photosynthesis, which is the production of sugars. When balancing your soil minerals, use naturally occurring mineral forms wherever possible, and add more compost (humus) at the same time.

Using the organic approach gives healthier, hardier plants over all, not just better tasting fruits and vegetables. By following these guidelines, create a disease- and pest-resistant garden that is inviting to beneficials (pollinators, for example). It follows that this approach will make for a healthier garden overall, whether you're interested in fresh fruits and vegetables or a beautiful floral display.