As society becomes more health and environmentally conscious, you're likely paying more attention to the size of your household's carbon footprint and what you feed your family. If you grow a home vegetable garden or feed your lawn and landscape, you may wonder if chemical fertilizers are really the best products to use. It's true that chemical fertilizers create runoff, contribute to greenhouse gasses and require frequent application. They do have their benefits, however. Chemical fertilizers offer greater control over the amount of nutrients you feed your plants than their organic counterparts. Manufactured fertilizer is also much less likely to add weeds to your garden, benefits plants more quickly than organic fertilizer and requires smaller applications. It's important to weigh both the pros and cons of chemical fertilizers before deciding whether to use them.
The WYSIWYG Benefit
Many computer interfaces operate on a WYSIWYG system, and so do manufactured fertilizers. In the computer world, WYSIWYG stands for "what you see is what you get," and refers to programs that allow users to print documents that appear the same on paper as they do on the screen. Chemical fertilizers work the same way. The fertilizer ingredients are carefully measured and their amounts listed right on their packaging. When you use them, you know exactly how much of a given element you will add to your soil. Because of their sources, organic fertilizers are a bit more unpredictable. Many come from manure, for instance, and it's impossible to know exactly what a certain animal ate and how its body processed it.
Chemical fertilizers allow for greater control over the amount of each nutrient they contain. Lawns, for example, often need large amounts of nitrogen and smaller amounts of phosphorous and potassium. Manufactured fertilizers make it easy to pick up a bag of high-nitrogen fertilizer that won't add other unnecessary elements to the soil. Even if you choose a nitrogen-rich organic fertilizer like bat guano, there is a limit to how much nitrogen the bat waste contains. Manufactured fertilizers don't have these limitations. You can purchase a processed fertilizer of almost any specification, getting only what you want in the amounts you need.
Just as important as what you will get with chemical fertilizers is what you won't. Animal waste and compost piles sometimes contain the seeds of unwanted weeds and plants. It may also contain insect eggs. A factory allows for absolute control of the manufacturing process. When you buy a bag of high-quality chemical fertilizer, you do so with the assurance that there aren't pests and weeds lurking in the product. Organic fertilizers simply can't make the same promise.
Organic fertilizers are often rich in nutrients and extremely beneficial for plants. Unfortunately, the nutrients they contain don't make themselves immediately available for plant use. Compost, manure and other organic fertilizers are complex in nature. The nutrients they provide exist in the material until microbes and bacteria in the soil break the fertilizer down into usable parts. Manufactured fertilizers, however, have the advantage of being immediately useful to plants. The nutrients plants need come from the fertilizer in usable form so that plants receive an immediate benefit.
The immediate nutritional access that chemical fertilizers provide is one of their benefits, but it also leads to one of their drawbacks. Because plants are able to use the nutrients that chemical fertilizer provide so quickly, you'll need to reapply the fertilizer with some frequency. Organic fertilizers take longer to work, but this creates a slow-release effect that keeps plants happier longer. Depending on your soil deficiencies and the nutritional needs of the plants you choose to grow, you could find yourself spending quite a bit of time working in the garden.
Feel the Burn
Chemical fertilizers make it easy to get too much of a good thing. Manufactured fertilizers contain mineral salts, and too much salt dries out plants. If you over-fertilize your lawn, garden or container plants, the salts in the fertilizer will damage the plants, causing fertilizer burn. Although the plants are actually drying out and not burning, their leaf tips and edges will turn brown, making them appear burnt. It also affects the plant's roots, which turn brown or black and become limp. Fertilizer burn is sometimes fatal. Organic fertilizers can also cause the burn, but it takes very large quantities to do so.
Although chemical fertilizers do an excellent job of amending poor soil, not every part of the ecosystem enjoys them. When saturated by rainwater, chemical fertilizers can move to areas where they don't belong through runoff. If this happens, the fertilizer can contaminate waterways and underground water sources, potentially harming local wildlife or people. Organic fertilizer runoff can do the same but is slightly less likely to do it. Organic fertilizer suspends its nutrients in other material until soil microbes break it down, holding onto them more firmly and making runoff less likely.
Sometimes runoff helps invasive plants or feeds algae. Fertilized algae create algae blooms that can prevent other aquatic plants from receiving the sunlight they need. When the algae die and decompose, they rob water of the oxygen that both fish and plants need. The readily available nitrogen in chemical fertilizers sometimes evaporates into nitrous oxide. Scientists claim this greenhouse gas is 300 times worse than carbon dioxide. While most of the negative environmental impact of chemical fertilizers comes from commercial food production, every gardener using chemical fertilizers contributes to the problem, even in small amounts.