Soil & Compost- the perfect blend

Soil and compost- the perfect blend

Why is it important to understand what type of soil you are working with when gardening? Soil can be considered the skin of the earth. Just as you would determine if the skin on your body is dry, oily or a combination before you apply the proper type of lotion, experienced gardeners do the same about their soil before planting. Is it primarily silty, clay, sandy, peaty, saline or loam? Or is it an ideal soil combination of silt, sand and clay?

Soil has a unique blend of 45% minerals, 25% water, 25% air and 5% organic matter. An inch of topsoil can take up to 500 years to create. You can see why you want to understand your soil. It’s not just simply “dirt.” The minerals in soil consist of Nitrogen, Phosphorus and Potassium (N-P-K). The organic matter comes from compost.

Nitrogen is to plants like protein is to the human body. Nitrogen allows plants to use carbohydrates to create energy for growth and strength. Phosphorus is to a plant like lungs are to the body. Phosphorous allows plants to “breathe”, allowing energy to be transferred and stored as well as helping plants use water efficiently. Potassium is to a plant like a stomach is to the body. Potassium helps the plant metabolizes its food to create energy. Potassium also helps control hydration and biochemical reactions inside the plant.

You want your soil to have a healthy balance as mentioned above. Plants cannot grow well without the proper soil, just as humans do not thrive without a healthy diet. If your soil lacks essential minerals you can compensate by mixing it with compost to supply nitrogen, bone meal for phosphorus, and wood ash for potassium.

How can compost improve your soil? If you live with heavy clay soil you know it can take forever for water to drain and how the soil clumps up into “clay” balls. It is best to work a large amount of compost into clay soil when the moisture level is normal–not too wet and not too dry. After working compost into clay soil you will see improved drainage because the compost combines with the tiny clay particulate to form larger chunks. The larger compost-clay particles also improves air penetration into the soil. Increased air in the soil limits compaction which allows roots to penetrate the soil better. Lastly compost binds to the clay making the soil more workable and less sticky.

You can apply compost to sandy soil at any time without the additional challenges of working with clay. Those with mostly sandy soil may be frustrated by the speed with which water or fertilizers seeps right through it. Compost mixed with sandy soil increases water retention anywhere from 10 to 1000 times. The compost also keeps all the important nutrients in the root zone rather than letting them just wash away.

Once you have figured out what type of soil you have, you need to think about what types of vegetables or flowers, trees or shrubs you want to grow. Different plants have different soil requirements. To simplify things, you can’t go wrong mixing compost in with the top 2” of your soil to make sure you have a healthy balance of nutrients. Remember to reapply compost as a topdressing in the garden all season long. Compost not only amends soil and gives plants a boost right away but also slowly releases nutrients so plants can thrive for months.

Don’t forget that 5% of soil is made up of organic matter. Compost is that organic matter. Just as we care for our skin, we also need to care for our soil!

Sarah Everson is the business manager for Compost Joe’s Premium Soils and Organics, a private composting facility located between Fond du Lac and Oshkosh.  Sarah also offers seminars and private classes on composting. 

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