Symptoms of Improper Nutrition

What happens when an essential element is lacking? When nitrogen is lacking, the leaves become yellow and are unable to form chlorophyll. When phosphorus is lacking, the leaves turn dark green. One may infer, then, that elemental deficiency can be determined solely by looking at the plant and observing the symptoms. While this is true to a certain degree, experience is also required to accurately assess such deficiencies. For example, plants turn yellow when nitrogen is lacking. But they also turn yellow when potassium is lacking, when magnesium is lacking, and when iron is lacking.

Insufficient calcium results in degeneration of terminal root and shoot growth and malformation of young leaves. The deficiency itself, however, does not directly cause these problems. Lack of calcium leads to abnormally high uptake of magnesium; these symptoms, then, are actually indicative of magnesium toxicity.

In addition to suffering from deficiencies, plants can also suffer from an overabundance of elements. The enthusiastic gardener who supplies too much nitrate, for example, will reap plants having leaves that exceed the capacity of the roots to provide for them.