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Healthy soil should be our goal since soil is the foundation for our plants.

It’s important to know what kind of soil we have in order to make any needed changes. Whether it’s sandy soil, clay soil or wonderful loam soil, adding some organic matter will most likely benefit the plants. We usually talk about organic matter as the end result of our compost piles, but it can be crop roots, weeds, green manure plantings, wood ashes, animal manure, straw, shredded paper, wood or other decomposing vegetation.

Plants use several different elements, maybe even some that have yet to be discovered. We hear a lot about Nitrogen (N), Phosphorus (P) and Potassium (K). This triad is necessary and hungrily gobbled up by plants. However, in order to grow and produce their best, plants need more than NPK. Our food is a product of the soil, and sometimes soil is depleted of nutrients. Soil tests are important.

Pre-made fertilizer mixtures can be purchased, and ingredients will be on the labels. However, we all have some natural sources that will supply organic fertilizer at little or no cost. Using these sources in our soil can also save us money by keeping them from the landfill.

Fish tank water — as long as no antibiotics or other medicines are used — can provide a free supply of balanced NPK. Almost makes me want to have fish again. Almost.

Nitrogen — Legumes (beans, peas) have the ability to “fix nitrogen” by taking the nitrogen from the air and using it in the soil. This helps the other nearby plants also. Onions or garlic (Alliums) should not be grown beside legumes, because the Alliums will interfere with nitrogen fixation. Coffee grounds, brewed coffee, manure from grass-eating animals, decomposed organic matter and returning the Borage and Comfrey plants back into the soil (as green manure) will add nitrogen.

The meals — alfalfa, blood, feather and cotton-seed — are sources. Even alfalfa hay and pellets can be used. It’s important to add a source of nitrogen to vegetable plants every year, but the proper amount can vary greatly from plant to plant. Leafy lettuce will need a hefty amount. Too much on a tomato plant will produce a giant mass of dark greenery and little or no fruit.

Phosphorus — Rock phosphate is a good natural, slow-release source. Bone-meal and alfalfa-meal can be used. Place pieces of banana peel in the soil, especially near tomatoes and peppers (don’t disturb roots). Roses, also love banana peels. Comfrey added back as a green manure is a good source of phosphorus.

Potassium — Once again, use those big comfrey leaves, either chopped into the soil while still green or into the compost in the fall. The deep roots pull up organic nutrients from deep into the soil, and it’s important to get these nutrients transferred to the veggies. Banana peels, coffee grounds, kelp-meal, and hardwood ashes are all sources of Potassium.

Greensand has potassium and other minerals, and I am a firm believer in using nutritious greensand. A little goes a long way, because it’s usually expensive.

Egg shells are usually mentioned as a source of calcium, but they also provide potassium and other nutrients. Crushed egg shells are free soil food and they help to keep slugs out of the garden.

Happy gardening.

Gardening Partners is a non-profit founded in 2003 to serve Dickson County with gardening education and advice. Readers may submit gardening questions by email at or on the website, or by mail at P.O. Box471, Dickson, TN 37056.

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