DEMYSTIFYING FERTILIZERS
Story And Photos By Lorraine Ballato

Fertilizer is pretty simple, right? You go to your local garden center, buy one or more of those bags that has some numbers on it, put it in a spreader, walk all over your lawn one dewy morning, and you’re done.

Maybe it’s not your lawn you want to improve. Could it be your landscape that’s looking somewhat anemic, and you’re starting to think about what you can do to perk it up a bit?

What about your vegetables? What can or should you be adding to make them fruit earlier to yield bigger and better crops?

It’s easy to get lost in the ocean of options when you walk into the garden center: What do you add when, and what can you expect? Where do you even begin to assess all these needs?

To do that, we have to get down and dirty. Rule number one: Feed the soil and you feed the plant. Soil isn’t just dirt. If you were to place a small amount of your soil under an electron microscope, you would see it’s very alive with millions of microbes. They do the real work of bringing nutrients to plants as they process the various elements in the soil. Some of these organisms are beneficial fungi that envelop plant roots, others create substances that fight disease, and still other microbes continually move about as they process soil nutrients, making them available to plants.  An excellent book on this subject is Teaming With Microbes: A Gardener’s Guide to the Soil Food Web by Jeff Lowenfels and Wayne Lewis (Timber Press, 2006).

BASICS

Let’s get the easy stuff out of the way first: those three numbers you see on most fertilizer packaging you buy. They represent nitrogen (N), phosphorus (P), and potassium (K), in that order. This is known as the NPK number and is shown on the ingredients label as a percentage of total weight.  For example, if the posted number says 10-10-10, that means that 10 percent of the weight of the package is nitrogen, 10 percent is phosphorus, and 10 percent is potassium. The rest of the ingredients are “inert” or fillers.

MICRONUTRIENTS

If that’s all there were to it, it would be easy, but there are a host of minor nutrients that play a big part in plant health. You’ll most likely find these listed on packaging for non-lawn fertilizers.

• Boron (B) helps with flowering and fruit production but be careful here since it can be toxic. You might notice the deficiency on new leaves as they will be yellow and the growing tips will wither. In strawberries, a sure sign of boron deficiency will be lumpy and deformed fruit. Without adequate boron in the soil, plants may appear healthy but not flower or fruit; crop yield will suffer.
• Calcium (Ca) is critical to a plant’s ability to absorb nutrients and form strong roots. If you grow tomatoes, you might have already witnessed or experienced calcium deficiency with a condition known as blossom end rot.
• Copper (Cu) increases the flavor and sugar content of fruit and vegetables. Like boron, however, copper can be toxic if overapplied, so you need to be judicious in your use of this amendment.
• Iron (Fe) is essential for making chlorophyll and plays a big part in the manufacture of plant proteins. Certain plants are susceptible to iron deficiency, gardenia being one of them. If you’ve seen yellowing of your leaves, it’s a pretty sure bet that a dose of iron will correct it practically overnight.
• Magnesium (Mg) is a primary component of chlorophyll. It’s not to be confused with manganese, which has a very different role.
• Manganese (Mn) contributes to seed germination as it brings the fruiting and ripening of crops along.
• Molybdenum (Mo), although present in minute quantities, has been shown to contribute to several plant functions and without it certain plants won’t grow. The good news is that as long as you have lime in your soil, the “moly” as it’s called for short will be released and do its job.
• Sulfur (S) turns out to be important in the production of the protein content of food crops while it also assists the root development of plants.
• Last but not least is zinc (Zn), which plays a role in cell division, chlorophyll production, and moisture absorption.

Get your soil tested

Now that you know all about the Big Three and the micronutrients, your next step is to get your soil tested. That might mean more than one test depending on what you’re trying to accomplish. Your vegetable garden is a very different part of your property than where you’re trying to establish a peony bed or a backyard retreat where you can enjoy your morning coffee on the weekends. And all three will need to be assessed in terms of their nutrient content as well as their pH. Oh, didn’t I mention that yet? The fact is that even if you have exactly the right amount of nutrients in the right proportions, if the pH is wrong, the plants won’t be able to use any of it as that acid/alkaline state binds nutrients when it’s out of sync with a plant.

Soil testing is easy. You can send your soil away (see sidebar) or you can get a home pH and soil testing kit at a local garden center, hardware store, or a home improvement store. In many cases, the information in the home testing kits will include not just directions but information about plant preferences for pH and nutrient information.  The first year I used my home testing kit for my raspberry patch and followed the instructions including adding the proper amendments, we had the best raspberries I can remember in years and have done so ever since.

In addition to considering fertilizers, get a handle on the texture and structure of your soil. If you have poor soil structure or the texture needs correcting, no amount of fertilizer will yield satisfactory results.

You can test your soil texture pretty easily. You want to find out how much sand, silt, and clay you have in a particular sample of soil.

Use a clear glass jar with straight sides and fill it 1/3 with soil, 2/3 with water. Shake the jar well to mix the soil and water. Walk away and let it settle for a few hours to a full day. When you return, you’ll be able to roughly assess your soil texture. Sand will settle out at the bottom, silt will be above, and clay/organic matter will be on top and even be floating. Measure those approximate proportions to get an idea of what you’re working with so you know how to amend that particular area to suit your growing needs. For example, if more than half of the soil that settles is sand, you will have a very dry condition as sand drains very fast and doesn’t hold water. Unless you’re growing succulents or things that like arid conditions, you’ll need to add material that holds water and adds microbes (sand has almost no microbial activity). Compost and well-rotted manure are good amendments for such a condition. For a really thorough soil texture analysis, go to http://www.finegardening.com/how-to/articles/ hows-your-soil-texture.aspx and follow the instructions laid out in that article.

Okay, so now you’ve got your test results and you know what you need to add where. Remember to take measurements with you so you know how much to get.

Before you make your final list, let me give you one more thing to think about: organic fertilizers vs. inorganic fertilizers. Is there a difference? Simply answered, you bet!

Inorganic fertilizers come from other than natural sources and are nonrenewable. When overapplied, they can cause “fertilizer burn” which is harmful to plants (sometimes causing death) and even more harmful to soil as it kills the beneficial microbes when used in excess amounts. Inorganic fertilizers do nothing to add to soil health: they simply feed the plant, not the soil. Many inorganic fertilizers actually cause plants to become dependent on them like an addict to drugs so that without regular “fixes,” the plants will actually decline. That puts an extra burden on you to continually apply the fertilizer and adds cost. Nutrients are immediately available to plants and usually work quickly. You see results fast.

Organic fertilizers in contrast are derived from natural sources and work gradually. They put nutrients into the soil, which in turn feeds the plants. Their slow-release nature prevents fertilizer burn and precludes damaging plants and soil microbes. Plants take up food as they need it, slow and easy. There is no immediate burst of growth; top growth of plants grows in concert with improved strength of root systems that support plant health, making plants better resistant to disease and stress. This slow and steady feeding also is less stressful to plants as they don’t have a sudden top growth that roots can’t support in the long run.

ASSORTED FERTLIIZERS

For what it’s worth, here’s what I’ve learned over the years about fertilizing. First, in side-by-side trials over the past five years, whenever I have used a fertilizer that is specially formulated for the specific type of crop I’m growing (tomato, strawberry, etc.), that fertilizer has outperformed any other fertilizer. If there isn’t a specific formulation for the crop (e.g., nothing for beans or squash), then I have used a general formulation for “vegetables” and it has performed better than any other fertilizer, including compost. I attribute that to the inclusion of minute amounts of the micronutrients discussed earlier and/ or the right balance of the various components. Second, I always use organic fertilizer for food crops. Third, I always mix granular fertilizer into all containers at planting time and continue to feed throughout the season: those plants only have six months at most so why not give them their best shot?

As far as choosing what fertilizers to use, I have a few that I like and have stuck with them. I’m a big fan of kelp in all its forms, fish based products, aged compost, aged manure, compost tea, worm castings, and worm poop. There are some good labels in the marketplace that I trust. One is Espoma, the same folks that make Holly Tone. Another is Bradfield Organics. A third is Organica. More are coming into the marketplace every year. Your choice may be a function of what’s available where you shop. I read labels very carefully and freely call and e-mail manufacturers to better understand their product.  I stay away from blood meal and bone meal. Using material processed from slaughterhouses disturbs me, especially with the existence of mad cow disease. Considering I can get nitrogen and calcium from other sources like fish emulsion and rock phosphate. I’d rather be safe than sorry. I also think blood meal and bone meal draw critters into the garden as they can smell the source material.

Things like aluminum sulfate, greensand, triple phosphate, and all the other items in garden centers are designed for specific plants and/ or specific deficiencies. You wouldn’t take aspirin unless you have an ache or need to thin your blood, so using these other products without having the condition(s) they address is not always a good thing: more is not necessarily better.

Last, if you have questions about soil testing and fertilizers, contact your local cooperative extension office. They are fully staffed for the growing season and can help you deal with your home and garden issues.

Lorraine Ballato is a garden writer and speaker who teaches classes and speaks to civic groups, garden clubs, and other organizations in the tri-state area. Her recently published book, Successful Self- Watering Containers: Converting Your Favorite Container to a Self-Waterer, is available through booksellers and also at her website. www.successfulselfwateringcontainers.com