How to Amend Soil

Soil amendments can be purchased in bulk for large jobs or bags for small garden areas.

Amendments are added to soil to improve nutrient levels, drainage capabilities and pH. Having the soil tested by your local extension office is the most reliable way to determine whether it should be amended to improve nutrient and pH levels. They can tell you what deficiencies the soil has and give you amendment recommendations. You can test your own soil for drainage capabilities, though. The results of this test will help you determine what amendments should be added.

Things You'll Need

• Large coffee can or plastic container
• Dirt or hand shovel
• Water
• Organic matter
• Perlite or sand
• Fertilizer
• Rototiller

Instructions

1. 

   Organically rich soil is dark and crumbly.

   Cut the bottom out of a large coffee can or plastic container of approximately the same size. Use a dirt or hand shovel to dig a 4-inch-deep hole in the soil that is the same diameter as the container. Push the container down into the hole all the way to the bottom and fill it with water. Check the water level after one hour. If the water level is down 2 to 3 inches, the drainage capabilities of the soil are good. If the level has dropped 5 inches, the soil is draining too quickly. Drainage capabilities are poor if the water has not soaked into the soil at all.

2. 

   Loamy soil is considered the best type of soil for many garden plants.

   Amend soil that drains well with organic matter every three to four years to maintain its good consistency and boost nutrient levels. Apply a 2-to-3-inch-deep layer of organic matter such as cow manure that has aged for at least six months or compost. This type of soil is often loamy soil.

3. 

   Sandy soil is normally low in nutrient levels.

   Amend fast-draining soil with organic matter to improve nutrient levels and slow the drainage rate. Use organic matter such as sphagnum peat, well-aged manure or compost. Apply a 4-to-6-inch layer the first year, preferably before planting. Apply a 3-to-4-inch layer each year from the second year on. This type of soil is often sandy soil

4. 

   Clay soil is ordinarily high in nutrients.

   Amend soil that has poor drainage capabilities with organic matter, perlite or sand every year. A 3-inch layer of organic matter such as shredded hardwood bark and wood chips will improve drainage. However, for several months after adding bark and wood chips to the soil it pulls nitrogen from the soil as part of decomposition. High nitrogen fertilizer may need to be applied, depending on the needs of the plants. Perlite is inorganic matter that can be used to improve drainage. Apply it in accordance with the manufacturer's recommendations. Apply coarse sand along with organic matter instead of perlite if preferred. Use caution when adding sand instead of perlite as it can bond with the clay and develop a concrete-like consistency. Such poor drainage capabilities are typical with heavy clay and silt soils.

5. Amend the soil with sulfur or lime to make it more acidic or alkaline only after it has been tested. Have it tested for salt and nutrient levels as well. Many plants are sensitive to high salt levels, and this could be a determining factor when deciding which organic matter to use. Add fertilizer to the soil amendments to improve nutrient levels as recommended by the extension office.

6. 

   Use a rototiller when amending the soil before planting.

   Work the amendments into the soil to a depth of 10 to 12 inches. Make sure all the amendments are mixed into the soil completely. Use a dirt shovel or hand shovel to carefully mix the soil amendments into the soil around shrubs and perennials.

References

• Mississippi State Univ. Extension Service; MSU Cares; Coast Gardener; Good Drainage Helps Plants Grow; December 2001
• Univ. of Minnesota; SULIS; Amending Soils for Perennial Beds; Jennifer Kaczmarski
• Colorado State Univ. Ext.; Choosing a Soil Amendment; J.G. Davis, et al.; May 2005
• Royal Horticultural Society: Soil Types