Many gardeners who contemplate going organic fall prey to the marketing hype of the big print on the package to make a purchasing decision. Although helpful in directing you to using something that could produce the desired outcome, it may not be what you really intended to put into your soil.
Let’s take a closer look.
Organic vs. nonorganic choices
All plants receive nutrients in chemical form. They cannot distinguish between how the nutrient was derived, whether organic or nonorganic. When referring to plant nutrition, “organic” or “natural” generally refers to any fertilizer with a plant, animal or mineral base. It must have one or more essential nutrients for plant growth.
Nonorganic fertilizers (also known as synthetic) are manufactured. They are made to deliver nutrients rapidly, such as those that are water-soluble or over time as a controlled release. Although very effective for providing rapid or prolonged periods of feeding, these have a high salt index. The potential risk to plants, the soil food web and environment includes burning and dehydration, and the leeching of unabsorbed chemicals into watersheds.
Organic nutrients, on the other hand, must first be broken down and digested by soil microorganisms, which then release these nutrients in a form available to plants while also improving soil structure. Unlike water-soluble synthetics, organically derived nutrients bind to soil particles and are far less likely to leech.
The net result is nutrients that remain in the soil until utilized by plants and little risk of burning or dehydration, even in periods of extreme drought or over-application.
You could sum it up by one gardening truth I live by daily: Feed the soil, and let the soil feed the plants. That, my friend, only happens as you build your soil health with organic amendments.
Look at any fertilizer package and you’ll find three numbers prominently listed. These are the primary nutrients that are needed in the greatest quantity by the plants. These numbers represent the percentage by weight of nitrogen, phosphorus and potassium found in each package.
Nitrogen is primarily responsible for vigorous growth and a dark green color. Phosphorus plays an important role in root development and flowering. Potassium helps with disease resistance and the overall hardiness of the plant.
Based on what you are trying to achieve for a plant’s growing success should determine which fertilizer to buy. Organic alternatives have lower ratios by weight, so it would take more to achieve the same nutrient level by volume. But unlike water-soluble synthetic fertilizers, organic nutrients stay in the soil, so less is needed.
Synthetic, manufactured chemical fertilizers are listed by their letters — for example, N for nitrogen, P for phosphorus and K for potassium. Organic alternatives, however, are often listed primarily by what they actually are, such as blood or bone meal or rock phosphate. Yet somewhere on that package, you’ll find the three important numbers. They are the key to knowing what role that product will play in your garden.
Here is a partial listing of the most commonly available organic nutrients sorted by their role for providing nitrogen, phosphorus or potassium.
Nitrogen: Dried blood, blood meal, cottonseed meal, fish emulsion and seaweed extract
Phosphorus: Bone meal, rock phosphate
Potassium: Greensand, sulfate of potash
I rely on these natural amendments to ensure that I’m feeding the soil, which in turn feeds the plants. OK, one more time. Repeat after me: “Feed the soil, and let the soil feed the plants.”
Make that mantra part of your new gardening protocol and you’ll be well on your way to a safer and more environmentally responsible approach to gardening.
Joe Lamp’l, host and executive producer of “Growing a Greener World” on PBS.
is an author and a paid spokesman for the Mulch and Soil Council. For more information, visit www.joegardener.com.