About Soil Amendments

Soil amendments are organic or inorganic matter added to the soil to improve texture, water retention, drainage or aeration. Sandy or rocky soil requires amendments to improve the texture and add water retention properties. Clay soils require the addition of material to improve texture, aeration and drainage. Soil amendments come in a variety of sources.

Function

Composted organic matter improves the texture of the soil, increases aeration, promotes both water retention and drainage as well as adds valuable nutrients necessary for plant growth. Home compost bins provide the main source of compost for home gardeners. Vegetation added to the compost bin breaks down into rich friable soil that provides valuable nutrients to the existing soil in the garden. Compost bins provide a convenient area to deposit leaves and plant material from harvests, grass clippings and organic yard debris.

Types

Peat moss sold in large compressed bales provides organic matter to soil. It increases the ability of the soil to retain water and is ideal for sandy or rocky soil. Peat moss is acidic and will lower the PH of your garden soil. Wood products like wood chips and shavings improve soil, but may create a nitrogen deficiency. Microorganisms in the soil use nitrogen to decompose the wood and may tie up useable nitrogen for weeks or months. Add a source of nitrogen at the time of application if you intend to cultivate crops on the soil. Composted manure improves the quality of the soil and provides nutrients necessary for plant growth. The addition of manure decreases the need for other fertilizer additives.

Identification

Vermiculite, a natural balsamic mineral and perlite made from heated amorphous volcanic glass sold for horticultural use, provides an inorganic soil amendment that increases aeration, improves texture and assists in water retention. Suitable for any type of soil, vermiculite and perlite do not alter the nutrient content.

Warning

Bio solids a byproduct of sewage treatment plants, usually composted with leaves or organic materials and sold as compost provide another option for soil amendment. Grade one bio solids approved for horticultural use should not be used for growing root vegetables. Bio solids contain high levels of metal and salts and any grade below grade one may contain pathogens.

Considerations

Consider the overall needs of your garden soil and choose amendments that match the needs of your soil. Enhance the soil by adding small amounts of amendments each year or by adding amendments to small sections on a rotating basis.