INTRODUCTION

Increasingly, people are thinking about and acting on what they include in their diets. There is a constant bombardment from health specialists, through the media and the internet, exhorting us to maintain a balance in what we eat, an important component of a well regulated lifestyle. Increasingly, we are learning that to eat immoderately and injudiciously is harmful.

We are also generally aware that plants become sick, just as animals do, when not supplied with the nutrients needed for good health. For animals, these requirements are elaborate and include the balanced provision of complex molecules in their diets, such as carbohydrates, fats, and proteins, as well as vitamins and certain minerals. Plants are different in being able to produce their own organic molecules from simpler, inorganic ones.

But, in common with animals, plants need certain minerals for healthy growth. Some of these are essential to both plants and animals in greater or lesser amounts; others are essential either to animals or plants but not both; and some are of probable, but at present uncertain, value to either.

ESSENTIAL MINERAL ELEMENTS

We eat some plant materials for their mineral content, like bananas for their potassium and spinach for its iron, nutrients which are essential both to animals and plants. Sodium is essential to animals but is required for only C4 plants. Molybdenum is essential to plants but is toxic to animals when more than a trace is present in food.