Marin IJ Articles
April 20, 2013
There's a whole lot of confusion when it comes to fertilizers.
Just check out the shelves at your local nursery or home improvement store. You'll find a mind-boggling array of things to sprinkle, spread, spray on, pour on, mix in, pound in; there's food, meal, pellets, all—in-one, time release, and don't forget the conditioner, compost, mulches and more.
Are they all fertilizers? Is a fertilizer the same thing as an amendment? A mulch? If not, what's the difference? And what do they do?
Plants require 17 chemical elements for healthy growth; the four general groups include the essential elements, carbon, hydrogen and oxygen, the primary or macronutrients — nitrogen, phosphorus and potassium, the secondary nutrients — calcium, magnesium and sulfur, and the micronutrients or trace elements — boron, chlorine, copper, iron, manganese, molybdenum, nickel and zinc. These elements are all plant nutrients. Most are already in the air or soil and don't need to be added. Some, like nitrogen, are rapidly used by growing plants and need to be replaced. Others may be present, but unavailable to the plant because of soil or environmental conditions.
Plants, like people, thrive on a well-balanced diet to keep them at their best. At times, their soil or environment may lack a key nutrient that can be provided as fertilizer, just as we might supplement our diet with a couple of vitamin C tablets if we're not getting enough from fresh fruits and vegetables.
Contrary to what product labels may claim, fertilizers are not plant food. Plants make their own food using water, carbon dioxide and sunlight. The food they produce, sugars and carbohydrates, are combined with plant nutrients to create the proteins, enzymes and vitamins that are vital to plant growth.
Let's clarify the terminology:
The law requires that manufacturers guarantee the accuracy of what is claimed on a product label — if it's on the tag, it's got to be in the bag. Fertilizers contain active ingredients — the materials responsible for the intended beneficial purpose of the product (think nitrogen or phosphorus). They also can include inert ingredients or filler which are included but have no intended nutritional value. Soil amendments make no legal claims about nutrient content or other helpful (or harmful) effects they may have on the soil and plant growth.
Inorganic fertilizers are single or compounded chemical elements while organic fertilizers are derived from plant or animals. A complete fertilizer contains all three primary nutrients; an incomplete fertilizer is lacking one or two. There are oodles of forms and formulations of fertilizers available — some of the more common include:
So, before you reach for an all-purpose tonic for your plants, think about a balanced diet and good nutrition — for you and your plants!