AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Fall 2000, No. 1
We value plants for the organic materials we eat – carbohydrates, proteins, oils, and vitamins. Plants have the unique ability to convert carbon dioxide in the air into these edible compounds. That’s why plants are called primary producers – they make the organic out of the inorganic.
Plants take up 14 essential minerals as inorganic salts. That’s true no matter how they are fertilized, whether with manure, compost, commercial fertilizer, or even if they are left to depend completely on the soil. Let’s look at a few examples of how these minerals control the levels of organic substances in plants.
Nitrogen is best known for building protein. As the amount applied increases to its optimum, the concentration of most other minerals in the plant increases as well. Either excess or deficiency can produce lower quality, so it’s most important to balance nitrogen with other nutrients.
Phosphorus increases grain phytate content. While phytate has long been considered an anti-nutrient, nutritionists are re-examining its role in the prevention of certain cancers. Phytin is an organic storage form for important dietary minerals like calcium, zinc and iron.
Potassium increases lycopene in tomatoes, carotene in corn, and vitamin C in many fruits and vegetables. It has been associated with higher isoflavone levels and better seed in soybeans.
Sulfur is part of two important amino acids, cysteine and methionine. The supply of sulfur can influence the kind of proteins formed and the bread-making quality of wheat.
Chloride remains mostly a free anion, but science has found more than 130 natural chlorinated organic compounds in plants. Chloride suppresses many diseases such as root rots and rusts in wheat, stalk rot in corn, and hollow heart in potatoes and thus can boost crop quality. It frequently increases kernel weight in cereal grains.
Micronutrients such as manganese, copper, iron, and zinc support the activity of enzymes, organic molecules that catalyze the synthesis of many unique and essential phytochemicals.
Consumers need more than empty calories. Two billion people in the world today are short of one or more nutrients in their diets. Shortage of calories is not as common as it used to be, but deficiencies of trace elements, vitamins and other phytochemicals continue. Balanced supply of mineral nutrients, using both organic and inorganic sources, can boost nutritional quality of food.
According to the USDA’s recently proposed organic standards, the term “organic” defines food produced without a long list of specific crop growth enhancing technologies. Balanced fertilization is one technology that can help attain the goal of producing healthy food; food that is more truly organic.