As a landscape contractor and nursery owner I am asked to make fertilizer recommendations on a daily basis. The general public has been led to believe that they must have a special fertilizer for the lawn and a different formulation for vegetables, flowering plants, trees, roses, houseplants, etc. It comes as no surprise as you browse the shelves of any garden center or notice all the ads in catalogs, magazines, newspapers, and on TV. The public is bombarded with so much information that they can become confused. It may seem to some folks much easier to simply grab a bag of “rose food” for the roses you bought, “tomato food” for the tomatoes, and of course you might as well get some “weed AND feed” so you can kill those weeds while fertilizing the lawn (sounds like a good deal, doesn’t it?). Finally the customer gets a handful of “tree spikes” for the trees and heads on to the check out counter feeling they have done the right and necessary thing.
As an honest salesman I often get the raised eyebrow when I give what I believe is the correct answer to the fertilizer question. That is, all plants (whether they be grasses, trees, or roses) need the same basic nutrients. The three numbers we read on any and all fertilizers describe varying amounts of nitrogen (N), phosphorus (P), and potassium (K). These are the three basic elements (called macro nutrients) that all plants use. If you will examine the “special formulations” that you buy for all your different plants you will see that the only real difference occurs in the “balance” of these three numbers and/or the inclusion of various trace minerals or elements (known as micro nutrients). A fertilizer formulated for “flowering plants” for instance may show a higher phosphorus count (middle number) because it is known that phosphorus is used in the development of flowers so we assume that giving extra phosphorus will mean more or possibly bigger blooms. Lawn grasses, on the other hand, are known to be “heavy feeders” so the nitrogen (first number) will be higher on that fertilizer.
The question that should come to mind is just how how much is enough and when is it too much? How do we know just how much phosphorous that flower will need? How do we know when to stop applying nitrogen to the lawn? Most of us have had the experience of seeing our own grass or a friend’s lawn that burned from an overdose. While studies have been done and certainly application rates are given on the package, how do we really know when we are wasting time and money, destroying good soil, or causing pollution? Just how much N, P, and K are actually needed by the plant and how much is left behind to cause pollution or chemical imbalance of the soil? In all the advertisements, articles, and books I’ve read there are no exact measurements or clearly defined numbers. We assume then that what we are doing is just making sure that we are providing ample quantities.
Of course this is an understatement given the fact that we know that nitrates left over from fertilizers are one of the most common pollutants in our local water supplies. Chemicals from synthetic pesticides, fungicides, and herbicides are also cause for concern. So it is logical to say that we obviously have been using too much. It is also common knowledge that some of these products are just too concentrated and others are so toxic that they should not be used at all. While much of the pollution has been blamed on agriculture, testing done on storm water runoff has shown that toxins from samples taken inside the city limits often showed to be ten times greater than those collected in the countryside.
Let’s take roses for example, about three years back we had what I would call a “rose year.” That spring all the roses in town were blooming profusely. I noticed that regardless of whether the roses were in a well kept garden or out in a vacant lot, every plant I saw looked good and had lots of blooms. Obviously something was going on that was perfect for the rose. Most likely a favorable weather pattern. Whatever the reason, the roses were righteous that year and it did not seem to make any difference whether they had been fertilized or not. I wondered then how many people around town had paid the extra money for that special rose formula fertilizer. I also wondered if they noticed the rose in their “brown thumb” neighbor’s yard blooming just as well.On the other hand, I recently read an article about a famous rosarian and her secrets of success. This person was “feeding” her roses every other week using (alternately) three different fertilizers not to mention the occasional addition of mineral fertilizers such as bonemeal and foliar sprays. There is no doubt that the lady was highly successful and loved her roses but was (or is) all this intensive fertilization necessary? Certainly not. Although the lady was growing some mighty fine roses, the left over nitrogen undoubtedly was leaching into the local groundwater. Furthermore, all that lush growth is probably setting her up with some chronic insect and disease problems.
Overfeeding plants with high levels of nitrogen is kind of like an athlete on steroids. While enhancing short term performance may help the athlete win the race, constant steroid use can lead to addiction and long term health problems. High nitrogen fertilizers have much the same effect on plants. Overfeeding nitrogen causes lush top growth which, in the beginning, looks healthy. As time goes along the plant becomes weakened as spindly stems and poor root structures have a hard time keeping up with all the top growth. The plant may actually become so “leggy” that it flops over or become stressed when nitrogen levels drop. This weakened (or addicted) state is an open invitation for insects and disease. Ever wonder why those same garden centers that sell so many fertilizers also carry lots of pesticides and fungicides? Healthy plants, just like healthy people, are far less likely to have these problems. The athlete on steroids, the overfed couch potato, and the pampered rose have something in common. Health problems.
Okay, so by now I hope you are wondering just what the best fertilizer is. The answer is really two things that all the processed fertilizers in the world have never been able to come close to. That is decomposing organic matter (compost) combined with natural rainfall.
Even the least observant gardener will notice that the grass suddenly grew several inches after a good storm, or that the tomato seeds came up the morning after a nice shower (even though they had been watered diligently and fretted over for days). A good thunderstorm will produce combined nitrogen (ammonium) at about 4% by volume. This makes the astute gardener wonder why we would ever need fertilizers that contain 30 to 40% nitrogen (ammonium sulphate, ammonium nitrate) by weight. Rainfall also picks up airborne minerals and microbes from dust particles as it falls. As rain strikes the ground it absorbs even more minerals and nutrients as it dissolves bits of rock and percolates through decaying organic matter. The plants receiving this blessing of highly fertile water will have stomata (breathing pores) open and root structures siphoning all they can hold. After the storm passes the plants have all the moisture and nutrients they need to produce chlorophyll from sunlight so maximum growth can occur. As the soil begins to dry the plants will continue to feed on rainwater stored in the soil profile sending their roots ever deeper in search of the nutrient rich moisture.
Compost is nature’s way of recycling organic matter. As plants and animals live they produce waste products (leaves, manure, dead tissue). When death comes then the entire organism begins to decompose. Every part of the living organism eventually decomposes entirely. As it does, all the various minerals and elements are returned to the soil to feed new life. Everything is recycled, nothing is wasted. Gardeners speed up this process by making compost piles. These piles are occasionally turned or disturbed by using a digging tool to introduce fresh air into the mass. Fresh air stimulates the reproduction of bacteria, fungi, and other microbes that feed on the decaying pile. Large quantities of compost can be made in a single season as long as fresh air and moisture supplies are adequate. When the mixture begins to turn into a dark brown to black crumbly material it is ready to be used. Well made compost will consist of a variety of components as opposed to just grass clippings, just horse manure, or just leaves. Layer the three together and mix as you turn to get better results. Even kitchen scraps and pet manures can be added to the pile with little or no concern of odors and insects. Well made compost will contain all the nutrients needed to sustain healthy plants.
Try this simple test. Take a sample of unimproved soil and send it off to a lab for testing. Save the results for comparison. Now take the same soil and mix in a couple of inches worth of compost. Let this mellow for a month or so and send this new sample in. You will see improvement of all available minerals and elements. Salts (chlorides) will decrease and the PH will move toward neutral or slightly acid. In short, the second sample will be much improved. Now think about what an inch of compost could do for your lawn, your flowerbeds, or even a hundred acre wheat field.
Besides feeding the plants, compost improves the soil itself. Clay soils will drain better. Sandy soils will hold moisture. Acid or alkaline soils will move towards neutral on the PH scale. Finally the compost will become humus. Humus contains humic acids that do some wonderful things like neutralizing heavy metals and other toxins. The humic acids also fight off disease organisms in the soil itself and make us (or whatever animal that eats the produce) healthier. Humus also acts as a sponge to hold dissolved minerals and nutrients until the plants need it. Humus creates an environment for the millions of microbes to thrive in the rhizosphere (root zone). These microbes live symbiotically with root systems and perform a multitude of functions such as keeping the root tips clean or protecting roots from disease organisms. Other microbes can actually convert free nitrogen from the air and make it available in the soil.
If we have our compost tested as a fertilizer we will find the N value very low. Usually about 1% or less by weight. What the test doesn’t show is the huge volume of living organisms that are delivering a continuous supply of not only nitrogen but all nutrients as they live and die. What this proves to us is that soil fertility is really dependent on two things. That is, not only do we need to have a good balance of chemicals but we also need the living organisms to keep the steady supply of nutrients available. The failure of the synthetic fertilizers that many of us have come to rely on is that they only address the chemical side while actually depleting the life in the soil.
So do we have a need for packaged fertilizers at all? The answer is both yes and no. We know that we can grow perfectly healthy plants with compost alone. While it is relatively easy to add compost to the garden it is not so easy to compost a pecan orchard or hayfield. The sheer volume of material needed is staggering although it can (and has) been done. A more convenient and cost effective way to fertilize large areas is to switch to organic fertilizers.
Organic fertilizers come in three basic forms. Some are derived from manures and other by-products that put simply are pelletized, highly concentrated forms of compost. Others are processed feed products such as alfalfa meal, cornmeal, molasses, and cottonseed meal. The third type we call mineral fertilizers. Examples are humates, lava sand, green sand, and so forth. The mineral fertilizers contain little or no N but supply a broad spectrum of other elements and trace minerals. All of these fertilizers will improve soil structure and eventually break down to form humus. Organic fertilizers enhance and are actually dependent upon microbial activity in the soil.
Another beneficial way of fertilizing with organic fertilizers is called foliar feeding. Foliar feeding is about as close to the natural feeding from rainfall as we can get. It is especially helpful in the absence of rainfall. During rainfall events plants can absorb nutrients through the leaves themselves. We can mimic this by misting the plants early in the morning when the stomata are typically open to receive their daily dose of carbon dioxide. Stomata are located on the underside of the leaf so direct a fine mist from under the plant to get the best results. There have been several good mixtures of water soluble foliar fertilizers hit the market in recent years. You may choose to concoct your own mixture or simply make a “tea” from compost or cow manure.
So when folks come in the nursery and ask me to recommend a fertilizer I will first and foremost start with compost. We are finding a growing number of homeowners who have gone to the trouble of composting the entire lawn. Some of these people have reported that they have gone several seasons without having to add anything extra. Their lawns (some of them were quite large by the way) generally looked better (that’s right, better) than their neighbor’s who continue to pay for fertilizer or have professionals do chemical applications. Compost is very cost effective (free if you make it yourself). The same amount of money that you will spend on a single bag of a good fertilizer will buy you close to a ton of compost in bulk form.
If that customer has already composted and wants to fine tune the lawn, vegetable garden, or grow award winning roses, I will show them to the foliar sprays, mineral fertilizers, and what I feel are the best organic fertilizers. Even so, I will caution against overfeeding. I will strongly caution against the use of high nitrogen synthetic fertilizers. Thirty years ago I used these “miracle” fertilizers just like most people, but by the time my wife and I decided to get into the retail nursery business I had already learned that these products only produce good results in the short term. In the long term, the soil becomes depleted of many life forms (earthworms are among those), humus levels begin to drop, and soil PH becomes so acidic that basic elements combine or “lock up” becoming unavailable to plants.
The handwriting is on the wall. We simply cannot afford to continue to pollute our soils and water supplies. Sooner or later this overloading of chemicals has to stop. I made the switch to organics in the 1970’s. Since then I have learned volumes and continue to be in awe of the complexity of what seem to be simple processes in nature. I encourage you to study on the subject of fertilizers to see if you don’t come to the same conclusions. For now, remember that just like people, plants love to be pampered. A little bit of pampering is sometimes necessary…………too much is disaster.