Good Soil means A Great Garden

A successful garden begins and ends with good soil. The best amendment to soil is organic matter. It will improve the texture, tilth, water and nutrient retention, aeration, and fertility. When organic material decomposes, it releases nutrients, including nitrogen. This nitrogen undergoes a chemical conversion until it is in a form usable by the plant roots.

 There are a number of organic materials that are suitable for incorporation into a garden. For amendments to be effective, they must be thoroughly mixed into the soil. Regardless of the material, a yearly addition of two inches is important. Compost, or “black gold” in gardening vernacular, is an excellent soil amendment and if kitchen and yard waste is composted at home, it is free. 

 Animal manure (herbivores only; no carnivores such as dog or cat) is another excellent choice.  Fresh manure is high in ammonia and can burn tender young plants. Therefore, composted manure is a better choice. However, a load of fresh manure (unless neighbors object to the fresh country smell) tilled into the soil in the fall and allowed to decompose all winter will not damage any plants. In addition, use in the fall reduces the risk of spreading pathogens.

 Peat moss was once considered a good soil amendment.  However, increased concern over the destruction of fragile bog systems has caused gardeners to reconsider. Peat is expensive, poor in nutrients, contains few beneficial microorganisms, and cannot be used as mulch. Compost on the other hand is free or inexpensive, relatively rich in nutrients (although not a fertilizer), has a multitude of beneficial organisms, and can be used as mulch. 

 If composting is not a viable option, direct incorporation of untreated grass clippings, straw, leaves, and other coarse materials into the garden can be used. These will decompose more slowly so adding them in the fall is the best option. Spread the material over the top of the soil and either let it stand over the winter or, ideally, till it in immediately. 

  “Green manure” or cover crops such as buckwheat, oats, or oilseed radish can be planted, allowed to grow for a period of time, then tilled under. These crops absorb and use nutrients which are then returned to the soil when they are turned under. The roots help keep the soil loosened.  Using a cover crop in the legume family, such as soybeans or clover, has the added benefit of fixing nitrogen by taking it from the air and storing it in root nodules. When the plants are turned under, the nitrogen is then available for future plant use. Further information is available in UW Extension Publication “Cover Crops for the Home Garden” at: http://learningstore.uwex.edu/Assets/pdfs/A3933-02.pdf

 One ill-advised soil amendment is adding sand to clay soils. Although it may seem like a good idea on the surface, it creates a soil structure similar to concrete.

 An easy and effective way to get the soil amendment into a garden is to add organic mulch around the plants in the spring. Mulch is organic material (such as grass clippings, straw, leaves, etc.) used on the surface of the soil to help retain water, repress weeds, and maintain soil temperature.  Once the growing season is over, the mulch has served its purpose and can be incorporated into the soil as an amendment. 

 All soils benefit from the regular addition of organic matter.  Having healthy soil is the foundation to a healthy garden.

 Carol Shirk

Certified Master Gardener