The chemical components of soil and the need for fertilizer

There are six nutrients, commonly called macronutrients, which are essential to the lives of plants. The nutrient that is most often lacking is nitrogen. In addition, phosphorus and potassium are generally needed for annuals, bulbs, and perennials with shallow roots, and turf.

All nitrogen comes from non-soil sources - organic matter, air, water, or fertilizers. Plants use nitrogen to form proteins, chlorophyll and enzymes, essential for plant cells to live and reproduce.

When nitrogen is lacking, the plant's leaves turn yellow from the tips to the stems and growth is stunted.

Many plants need extra nitrogen - often added in the form of fertilizer - occasionally to ensure healthy growth.

When you purchase fertilizer, the first number you see indicates the percentage of nitrogen. The second number represents the percentage of phosphorus. Many annuals with shallow roots, bulbs, perennials, and lawns, do not have enough phosphorus. The best way to add a phosphorus fertilizer is to place plenty of it where roots have access to it.

The third number on the fertilizer label is potassium, often needed for annuals and perennials. Most soils that are lacking in potassium will be acidic, sandy, and lacking in organic matter. Like phosphorus, it should be placed near the roots. Use quality garden tools that help make the job easier.

Another trio of macronutrients found in some fertilizers are calcium, magnesium, and sulfur. There are generally enough of these in the soil. One exception is in high-rainfall areas, where the nutrient is often washed away.

Calcium aids in making and growing cells. Magnesium forms the core of chlorophyll molecules, and sulfur works with nitrogen to make new protoplasm for plant cells.

In dry areas, additional iron, zinc, and manganese are sometimes needed for proper growth.

Fertilizers come in dry and liquid forms. Wear gardening gloves when handling these materials.

All great gardens begin with great garden soil!