Every time you pick a cucumber, you remove nutrients that came from the soil. Unless you use fertilizers to replace those nutrients, your soil will gradually become depleted and your garden less productive.
All materials that supply nutrients to growing plants are fertilizers, though they may differ in the amounts of nutrients they carry. Fertilizers are labeled with their grade, or analysis, which expresses the percentage of the major nutrients in the material. The first number always represents the percentage of nitrogen; the second, phosphorus; and the third, potassium. Thus, a bag of 51010 fertilizer contains 5 percent nitrogen, 10 percent phosphorus, and 10 percent potassium.
Feeding Your Vegetables
Usually, the higher the analysis, the less expensive the material. A 50-pound bag of 51010 might cost $5 and a 50-pound bag of 102020 $8. You’re getting twice the nutrients in the bag of 102020 for less than twice the cost. The higher-analysis fertilizers are more concentrated, salts, however, so you must apply smaller amounts to your plants or you’ll burn them.
The fertilizer ratio expresses the proportion of one nutrient to another. For example, 51010 and 102020 have different analyses but the same ratio, 122.
Fertilizers come in two types: commercial and organic. Many people call the former chemical fertilizers, some with the idea that all chemicals are bad. This is silly, since organic fertilizers are made of chemicals, too, as are the plants. In fact, a bag of organic fertilizer has hundreds more chemicals in it than a bag of commercial fertilizer. Both types of fertilizers contribute different things to the vegetable garden. Neither is all good or all bad; each has its good points and bad.
Commercial fertilizers are made of mineral salts mined from the earth. Some are treated chemically to concentrate their nutrients and make them more available to plants. The nitrogen is often a by-product of the oil industry. All the components come from the earth, then, and are no more man-made than cow manure. They’re just refined and concentrated. Because of this, you need much smaller amounts of them than of organic fertilizers. They are inexpensive, dry, easy to handle, and odorless, and their nutrients are more or less readily available for plant use. If they’re used improperly, however, their high salt concentration can burn plants and their rapid availability of nutrients can stimulate excessive plant growth at the expense of productivity. Tomatoes fertilized too heavily will grow tall and luxuriant but produce few mature fruit. Commercial fertilizers supply no soil-building organic matter and can speed the breakdown of soil organic matter already present.
Organic fertilizers are natural refuse products from plants and animals. They’re not concentrated, so you’ll need more of them to do the job. They’re often bulky and inconvenient to handle, like manure, and have strong odors, like blood meal and fish meal. These odors will sometimes attract pests, such as dogs and raccoons, to the garden. Organic fertilizers add varying quantities of beneficial organic matter to the soil. Because they are not concentrated, their salts are not likely to burn plants, although poultry manure can burn young plants because it liberates large amounts of ammonia.
The nutrients in organic fertilizers are bound up in large molecules that must be broken down by soil microbes before they are available for plant growth. This is done over time, and the liberation of nutrients from organic materials is difficult to control. This slow release has its advantages and disadvantages. Long-season crops will receive nutrients throughout the season, but short-season crops won’t be able to make use of all the nutrients. Also, you may not want some plants, such as tomatoes, to receive so many nutrients after midseason.
I use both commercial and organic fertilizers in my gardenthe commercial to supply the bulk of the nutrients quickly, and the organic to help maintain soil organic matter and supply smaller amounts of nutrients throughout the season. Studies have shown that this practice will produce bigger and better crops.
