Feed Your Soil

Every gardener amends his or her soil in some way at some time. One might add fertilizer, compost, and maybe even change pH. But what are the most effective things you can do for your soil? Can amendments harm your soil? The first step is to understand Iowa soils; the second is to understand your soil. Then amendments can begin.

Iowa Soil
Iowa soils are known for being among the best and most fertile soils in the world. Our soils are rich in phosphorous, potassium, and trace elements needed for healthy plants. In most cases, Iowa soils only need added nitrogen to perform well.

To be certain you know the nutrient content and pH of your soil; visit your local extension office. They will explain how to take a soil sample and will provide you an analysis for a small fee.

But if you have trouble soils or special needs, you may need other amendments.

Your Soil, Your Needs

Clay
A common problem, especially for people in new housing developments, is a soil that drains poorly. Setting water and sickly plants may indicate your soil is high in clay content. While past remedies for clay included additions of sand or gypsum, these two soil amendments can rarely be added in enough volume to change clay soils.

The most efficient addition to clay soils is compost. (Note, composted manure you see in stores will provide nitrogen, but will not provide the organic matter you need from compost.) Compost will add the organic matter needed to add structure to clay soil. This structure will permit the soil to drain more easily, provide for better nutrient uptake for plants, and allow more oxygen to reach plant roots. Often, only three inches of compost worked into the soil will begin to turn clay into tillable soil.

Sand
In rare cases, some Iowa soils drain too well and require water constantly. The best option to remedy this, again, is compost. Compost will boost sandy soil’s ability to retain moisture and nutrients for plants while giving structure to the soil.

pH
Sometimes it’s not the soil structure that can be a problem; it’s the pH. Most Iowa soils have a pH just above 7, or neutral pH. Most plants prefer a soil that’s slightly acidic, around 6.8. According to Iowa State’s Garden Soil Management if your soil tests above 7.2 or below 6.5, you may need to amend it, but you must test to be sure.

Often gardeners will add lime to ‘sweeten’ the soil or sulfur to make it more acid. Be cautious; adding too much sulfur, or too much lime, could damage your soil for years or even permanently! Check with your extension office before doing any pH amendments.

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So what’s best thing a gardener can do for their soil? Compost. It only makes up about 5% of soil, but it will add structure, balance poor soils, and add nitrogen with no risk of burning your plants no matter how much you add. Compost feeds your soil, so your soil can feed your plants.

A last question people always ask? Is there any difference between dirt and soil? Yes: dirt is misplaced soil. Good soil: the foundation to make your yard, your way.