How to Amend a Sodic Clay Soil

Sodic soils are those that contain high amounts of sodium and few total salts in general, resulting in conditions that are detrimental to the growth of many plants. Most plants are sensitive to sodium and will not grow well in sodic soil due to resulting nutrient deficiencies and high pH levels. Too much sodium tends to diminish soil structure, which becomes clay-like and lacks water retention. A high pH above 8.4 often indicates sodic conditions. To remove the sodium, either limestone or gypsum present in the soil is dissolved, or calcium is added. The calcium will displace the sodium and, along with the addition of other amendments, a proper soil texture and chemistry can be achieved.

Compost or other soil amendment
Sulfur
Calcium supplement
Shovel

Instructions

- 1
  Improve the drainage capacity and permeability of clay soil by incorporating an amendment such as compost, manure, wood chips, bark or perlite. Drainage is essential in order to allow water to leach excess sodium away. When amending clay soil, avoid applying sand, as this will create an undesirable soil texture akin to concrete.
- 2
  Apply sulfur or sulfuric acid to the soil if free lime is already present. The idea is to dissolve the lime, thereby releasing the calcium and incorporating it into the soil. If using elemental sulfur, apply 500 to 1,000 pounds per acre.
- 3
  Broadcast a calcium supplement, such as gypsum, to the soil surface if limestone is not present. You may also use calcium chloride, but it tends to be more expensive. Use a shovel to mix in the supplement and add water to ensure it dissolves and is distributed throughout the soil to a depth sufficient for growing plants, such as about 12 inches.
- 4
  Water heavily to remove any displaced sodium away from the root zone of affected crops.
- 5
  Plow deeply into soil layers to break up clay at subsoil layers and incorporate low-lying calcium layers if these are present.

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