From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Fall 1999, No. 1


Do foods produced from today’s high-yield crops have the same nutritional quality as those grown in generations past? Many worry that fertilizing high yield varieties produces “empty calories” rather than healthy food. Is this true?

It’s hard to find any evidence to justify the “empty calories” concern. One recent study in Norway compared the nutritional quality of carrots produced on 10 organic farms with those on 10 farms using commercial fertilizer. No differences were found in trace elements, vitamins or taste perception, except that the carrots grown with fertilizer had higher beta carotene. Not surprising, since other experiments have shown that carotene is enhanced by both nitrogen and potassium fertilizers. In many vegetables and fruits, potassium increases vitamin C content as well.

Lately, more and more consumers are seeking benefits in functional foods…foods that contain naturally occurring phytochemicals with medicinal or therapeutic value. Tomatoes, soybeans, oats, broccoli, and garlic are a few examples of functional foods. They contain “nutraceutical” compounds like lycopene, isoflavones, beta-glucans, sulphoraphanes, and allicin. The effects of many of these compounds are not yet well understood, but science is changing that quickly. The U.S. Food and Drug Administration has recently approved health claims on both oat fiber and soy protein for their roles in reducing risk of heart disease.

Fertilizers and soil fertility can influence the level of functional food components in crops. Soybeans contain isoflavones, thought to reduce risks of heart disease and cancer. Soybean isoflavone content can vary more than three-fold, depending on variety and growing conditions. In a recent field trial in Ontario, both higher yields and higher plant potassium status appeared to be positively associated with isoflavone levels.

Lycopene may reduce cancer risk. Today, biotechnology is promising new varieties of tomatoes with doubled lycopene content. Is it needed? More than 25 years ago, research showed that potassium fertilization could increase tomato lycopene by as much as 60 percent.

Phytate is another example of a food component being modified by biotechnology. Low phytate seeds of corn, barley and rice have been developed, but research has yet to develop a full understanding of the implications of low phytate for human health. While phytate is an anti-nutrient because it reduces availability of phosphorus, zinc, iron, calcium, and magnesium, it has benefits as well in reducing risk of prostate cancer.

Worldwide, fertilizer use has boosted the amount of calories available per capita, but micronutrient deficiencies remain widespread. In fact, it is estimated that 2 billion people are malnourished in trace elements and vitamins. There is a need to do a better job of supplying a nourishing diet. Agronomists can help by:

The goal of crop production is to nourish the world, and that requires more than “empty calories”. Fortunately, well-nourished crops can produce nourishing food. Supplying balanced fertility to the crop can yield better health as well as more calories.


For more information, contact Dr. Tom W. Bruulsema, Director, Eastern Canada and Northeast U.S., PPI, 18 Maplewood Drive, Guelph, Ontario N1G 1L8, Canada. Phone (519) 821-5519. E-mail:
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