The Coastal Gardener: Organic fertilizer is good for you, plants and Earth

Organic or synthetic? Most of the confusion I see regarding organic fertilizer falls into two groups.

Most questions have to do with trying to understand what the differences are, usually with an underlying question, "Why should I use organic fertilizer?"

The other uncertainty has to do with "What is an organic fertilizer?"

Because most people relate to fertilizing products by brand name, not ingredients, the second question is easier to answer than the first. Brands like Miracle-Gro, Scott's, Vigoro, Best, Osmocote and Shultz are synthetic, not organic, although each of these companies is attempting to enter the growing organic fertilizer marketplace. The most popular organic fertilizer brands are likely Dr. Earth, E.B. Stone, Whitney Farms and Foxfarm.

But the best way to distinguish organics from synthetics is reviewing the ingredients list. Synthetics will include sources like ammonium nitrate, monammonium phosphate, ammonium sulphate, urea, potassium chloride, etc. Organics will be from sources like bone and fish meal, rock phosphate, kelp, alfalfa and soybean, various guanos and so on.

Answering "Why should I use organic fertilizer?" takes a bit more explaining and gets a little technical. I'll try to simplify the science as best I can.

At the most basic level, organic fertilizer simply means a fertilizer derived from organic matter, such as from the ingredients mentioned above. Chemical fertilizers are usually processed from things like petroleum, or some of the gasses that are found in places where petroleum exists.

Chemical fertilizers, when mixed with water, are in a form a plant can use immediately. Nitrogen is present in forms that quickly dissolve in water to form a nitrate ion, among other things. Phosphorus is present as phosphate, which provides the phosphate ion. Potassium is usually in the form of potash, delivering a potassium ion. Of course, there are about 14 other nutrients that are also essential to plants, but there isn't space here to go into all of those.

Chemical fertilizers are easily over-applied because they are essentially all released to the plant right away. Perhaps even more important because they are water soluble and move wherever water moves, chemical fertilizers are much more easily removed from the root zone — and end up in our groundwater, watersheds and coastal waters. Also, chemical fertilizers generally are derived from non-renewable resources.