Understanding plant nutrients

In many soils, these elements are naturally present in sufficient quantity to meet the needs of trees, shrubs, and other large plants for many years. Still, gardeners often apply additional phosphorus and potassium to the soil when digging new beds, as part of annual care for heavy feeders such as roses, and to encourage the best performance from annual vegetables and flowers. Application near the root zone is easy when you're making a new bed. For permanent or semipermanent plantings, you can scratch the supplements into the top inch or two of soil (they'll gradually be carried downward by earthworms, rain, and soil-dwelling microorganisms) or, for a quicker effect, apply them in the form of a liquid fertilizer.

SECONDARY NUTRIENTS

SCalcium, magnesium, and sulfur are also important for plant health. They're largely available to plants through minerals in the soil. Calcium plays a fundamental role in cell synthesis and growth; most roots require some calcium right at their growing tips. Magnesium forms the core of every chlorophyll molecule. And sulfur combines with nitrogen in making protoplasm for plant cells.

MICRONUTRIENTS

The micronutrients include copper, iron, manganese, zinc, and other trace minerals. Copper and iron are used in chlorophyll formation. Manganese and zinc seem to function as catalysts in the utilization of other nutrients.

Micronutrients are usually available to plants through minerals in the soil. However, if the soil is highly alkaline, plants may be unable to absorb these nutrients in sufficient quantity for good health. Various products can be applied to soil or sprayed on leaves to correct deficiencies. The supplement most commonly needed is chelated iron (for iron-deficiency chlorosis); it can be sprayed directly on leaves and stems.

NUTRIENTS CHART

Macro-Nutrients

Chemical Symbol

Carbon

C

Oxygen

O

Hydrogen

H

Nitrogen

N

Phosporus

P

Potassium

K

Secondary Nutrients

Chemical Symbol

Calcium

Ca

Magnesium

Mg

Sulfur

S

Micronutrients

Chemical Symbol

Copper

Cu

Iron

Fe

Magnanese

Mn

Zinc

Zn