University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Improve Garden Soils in Off-Season

October 19, 2000

As gardens are cleaned-up and materials stored away until next season, improving soils is often overlooked. Improving garden soils is an important task for the off-season, in particular fall. Addressing soil problems can mean improved plant growth next season.

Soil tests can be useful in determining improvement needs. Key information soil test results will show include the soil pH value and levels of both phosphorus and potassium. Once this information is known, adjustments can be made as needed. Check with your local University of Illinois Extension office for information on testing soils.

Soil pH is a measure of how acidic or alkaline a soil is. Values of 7.0 are considered neutral; with pH values lower than 7 considered acidic and higher than 7 considered alkaline. For example, a soil pH reading of 6.2 would be an acidic soil, whereas a soil pH reading of 7.7 is an alkaline (or basic) soil. Soil pH values just slightly acidic (6.5-6.8) are ideal for most plants.

Once pH values are known, amendments can be added if needed. Many soils in our area tend to be alkaline and may need to be lowered to neutral or slightly acidic ranges. Use elemental sulfur to achieve this, and base the amount on the soil pH value and type of soil. Acidic soils can be amended with limestone to make them less acidic; but this should be based on a need shown by a soil test.

Another way to amend garden soils in fall is adding organic matter. Organic matter help improve the ability of soils to hold nutrients for plants, improve soil aeration for roots, and to some extent improve soil drainage. Types of organic matter to use as soil amendments include compost, rotted manure, peat, and similar materials. Work these into the soil this fall for maximum benefits. Organic matter is the best choice to help improve our heavy clay soils.

Major nutrients such as phosphorus and potassium can also be added to soils in fall. Once again, the best way to determine how much to add is the soil test results.

Take some time this fall to improve garden soils. The results of your efforts may be very visible in the seasons to come!


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