The organic advantage

Organic fertilizers, manures and composts release their nutrient content only as they decompose -- as they are slowly broken down by the complex ecology of living creatures in the soil. Complete decomposition of most organic fertilizers takes around two months in warm soil. During that time, they steadily release nutrients.

Nonorganic synthetic fertilizers, on the other hand, should come with labels warning against overdose. They are so strong that it's easy for inexperienced gardeners to cross the line between just enough and too much.

Yet, despite their strength, inexpensive blends are incomplete. They supply only nitrogen, phosphorus and potassium. Unless the manufacturer intentionally adds other essential minerals, the chemical mix won't supply them. Chemical fertilizers rarely contain calcium or magnesium, which plants need in large amounts along with tiny traces of several other minerals.

Problems of chemical blend

Inexpensive chemical fertilizers dissolve quickly in soil. This usually results in a rapid burst of plant growth, followed five or six weeks later by a big sag, requiring yet another application. Should it rain hard, the chemicals dissolved in the soil water will be transported as deeply into the earth as the water penetrates (this is called "leaching"), so deep that the plant's roots can't reach them. With one heavy rain or one too-heavy watering, your fertile topsoil becomes infertile. The chemicals also can pollute groundwater. The risk of leaching is especially great in soils that contain little or no clay.

Chemical fertilizers can be made to be "slow-release," but these sorts cost several times as much as those that dissolve rapidly in water. The seed meals in this organic fertilizer mix are natural slow-release fertilizers, and they usually are less expensive than slow-release chemical products. Complete organic fertilizer mix

Bone meal, 1 part

Kelp meal, 1/2 part

Dolomitic lime, 1/2 part

Soybean meal, 4 parts

Agricultural lime, 1/2 part (or 1/4 part agricultural lime plus 1/4 part gypsum)

上一页  [1] [2] [3]