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A rich, well-fed soil is all that most plants need to keep them growing vigorously. Few soils are naturally well fertilized so gardeners can enhance the fertility of their soils by adding organic fertilizer. Not only will organic fertilizers provide a wide array of nutrients to the soil, they encourage microbial activity, which allows the organic fertilizer to provide nutrients over a longer period of time. Unlike chemical fertilizers, the nutrients in organic fertilizers are less likely to leach away in rainwater.

In the range of organic fertilizers, gardeners are not limited to manure & compost. Although these fertilizers are abundant and easy to find, they can be the source of weed seeds and chicken & steer manure can be contaminated with antibiotics and other agrochemicals used in raising these animals. Alternatively, there are numerous other sources of organic fertilizer including alfalfa meal, canola meal, rock phosphate, bonemeal, kelp meal, and greensand. All of these fertilizers are naturally occurring but it is important to choose the right one for your plants' needs.

All of the seed meals including alfalfa, canola, and cotton meal are great sources of nitrogen. Nitrogen is necessary for healthy leaf & shoot growth. Leafy plants such as lettuce, spinach, and even corn require high amounts of nitrogen. Rock phosphate and bonemeal, on the other hand, are rich sources of phosphorus. This element encourages good root growth and is essential when growing potatoes, carrots, turnips, and radishes. Lastly, kelp meal and greensand, both full of potassium, aid in fruit and seed development and will help give a bumper crop of tomatoes, peppers, eggplant, and squash.

Not only do organic fertilizers provide these major nutrients, nitrogen, phosphorus and potassium, they are full of micronutrients, which are also essential to plant growth. Kelp meal, in particular, is rich with boron, calcium, sulfur, magnesium and manganese. In addition, kelp meal contains naturally occurring growth hormones, which stimulate plant growth.

It's often difficult to judge exactly what nutrients to supply unless you take a soil test. However, by combining organic fertilizers, you ensure that all the nutrients required for growth are available. A great recipe for an all-round organic fertilizer follows:

4 parts seed meal (canola, alfalfa, or cotton)
1 part rock phosphate (or 1/2 part bonemeal)
1/2 part kelp meal or greensand

This organic fertilizer mix can be made ahead of time and stored in a sealed container in a cool, dry place. When planting in the garden, use 1/4 cup of the mix under light-feeding plants such as beans, carrots, beets, and lettuce. Use 1/2 cup of the mix under heavy-feeding plants such as tomatoes, peppers, squash, and broccoli.