Is Fertilizing Necessary, and How Much Is Needed?
Soil fertility is always changing; nutrients are used up by growing vegetables, the soil structure is disturbed by tilling, nutrients are leached out by the rain, and topsoil is stripped from the beds by the wind. To grow great vegetables, it is important to fertilize so the plants have access to all the nutrients they need to grow well. The three main elements needed for good plant growth are nitrogen, phosphorus, and potassium. These are needed for leaf, stem, and root growth as well as for forming the buds, flowers, and ultimately, the vegetables you will be eating.
There are two ways to fertilize—you can choose to feed the plant or feed the soil. To feed the plant you use chemical fertilizers, which will make your plant grow but do not benefit the soil in any way. Feeding the soil involves using organic fertilizers as well as amending the soil by adding different organic materials to it. The organic fertilizer adds nutrients while the organic matter decomposes over time adding to the soil fertility.
Choosing how to fertilizer is a personal choice; however, if you are planning to have a long-term healthy garden it is best to use organic methods. Soil is a living thing. Keeping it healthy is important to get great tasting, chemical-free vegetables. Using organic growing methods are better for your health, the health of your family, and the health of the environment.
There are eight common trace elements that are needed for good vegetable plant growth. They are calcium, sulfur, iron, boron, copper, manganese, molybdenum, and magnesium. There are usually sufficient amounts of these elements in garden soils so you do not need to add them in.
Some examples of organic soluble fertilizers (meaning they dissolve in water) are liquid kelp, or liquid fish emulsion, which you mix with water and put into the soil when watering your garden. Some common nonsoluble organic fertilizers are cottonseed meal, blood meal, bone meal, green sand, and rock phosphate. These are best added to your garden bed directly in the spring and tilled under. Nonorganic fertilizers, also known as chemical fertilizers or pesticides, are man-made from petroleum products and should be avoided if possible, as the chemicals will be ingested when you eat the vegetables.
How Much Is Needed?
Amending your soil on a regular basis with organic materials and organic fertilizer is important in any garden. As often discussed, plants need nutrients to grow and often will use up everything they can reach in one season. So it is important to keep adding in more nutrition each year. Plants require three main elements to grow: nitrogen, phosphorus, and potassium. All these elements are found naturally in the earth but not always in the quantity needed for growing vegetables in your back yard soil, and especially not if you are growing veggies in containers.
Nitrogen (N) is needed for leaf and stem growth, and it gives the plant a green color. Some organic sources of nitrogen are blood meal, fishmeal, alfalfa meal or pellets, and cocoa shells. Some animal manure such as chicken manure has a high nitrogen concentration. Some signs your soil may be deficient in nitrogen are the leaves of the plant are turning yellow, the leaves are falling off, or the plant is looking stunted and not growing well. On the other end of the scale, too much nitrogen in the soil may lead to leggy, spindly plants or plants that have lots of green leaves but are not producing any fruits or pods.
The code for nitrogen is an N, for phosphorus, it is a P, and for potassium, it is a K. This is a universal code displayed on bags of fertilizer and can be used as a quick reference when purchasing specific types of fertilizer.
Spreading the fertilizer gently around the base of the plant and watering it in can help a troubled plant fairly quickly. If you are going to be planting a new crop, rake or till the fertilizer into the first 6 inches of the garden bed. If your soil is very low in nitrogen, add five pounds per 100 square feet of the vegetable garden. If it is just a bit low, add in two-and-a-half-pounds per 100 square feet. To maintain a consistent amount, add one pound per 100 square feet every year. If you find your soil has an excess of nitrogen, try planting vegetables that need a lot of nitrogen, such as leafy greens, and make a note to do a soil test before adding any in the bed the following year.
Phosphorus (P) is needed for healthy plant roots as well as for the flowering and fruit growth of your vegetables. Some easy to access sources of phosphorus are a bone meal, fish emulsion, rock phosphate, and some animal manures such as horse manure. Plants that are stunted, very slow growing, or have dull-looking leaves with a purplish tint to them are all signs of a phosphorus deficiency in your soil. Few gardens have an excess of this element in the soil; fortunately, too much phosphorus will usually not have any adverse effect on your vegetable plants.
If your garden is low in phosphorus, add in six pounds per 100 square feet. If your plants are producing well, all you have to do is maintain a good amount of phosphorus in the soil by adding in one pound per 100 square feet each year.
There are many multipurpose organic fertilizers on the market if you do not want to add in several different types of fertilizer each year. Every garden is different, so make sure you take the time to observe your plants for signs of any deficiencies and add whatever may be needed.
Potassium (K) is needed for plants to produce leaves, buds, healthy roots, and flavorful fruits. Some common sources are potash rock, wood ash, and greensand. If your soil is deficient, your plants will be short and stocky and have a loss of color in the veins and brown spots on the underside of the leaves. Like phosphorus, there is not often an excess of this element in the soil, and if there were, it would not have an adverse effect on your plants.
If your soil is low in potassium, add ten pounds per 100 square feet of some of the organic sources. If you just want to maintain the amount you have in your soil, add two-and-a-half-pounds per 100 square feet each year.