Why Treat Corn with Lime

Soil Acidity

• The pH of soil is a number that represents how strong of an acid or base the soil is. A pH level of 7.0 is neutral. The pH of a soil affects how easily its nutrients are released to plants. Soil with a pH below 6.0 is acidic and does not release nutrients as readily as soils with pH levels closer to neutral. Soils with acidic pH levels also release too much of certain elements, such as aluminum and manganese, which can become toxic to plants in high amounts.

Corn Soil pH

• Some plants grow well in somewhat acidic soils, including corn. However, corn and many other plants start to suffer from nutrient deficiencies in soil with a very low (acidic) pH. The ideal soil pH for corn is between 6.0 and 6.5. Corn will often tolerate a soil pH slightly below 6.0, but corn grown in very acidic soil with a pH significantly below 6.0 may suffer stunted growth and yellowing leaves.

Lime Additives

• Lime soil additives raise the pH of soil, making it less acidic. Lime also adds calcium and magnesium to the soil. The amount of lime a soil needs depends on its density, current pH and desired future pH. Dense clay soils require more lime to alter their pH than light soils do. Most lime soil additives come from either dolomitic or calcitic agricultural limestone.

Soil Testing and Lime Application

• Test the soil pH and nutrient levels by using an at-home testing kit or sending a soil sample to a lab for testing. If the soil pH is much below 6.0, consider adding some lime before planting corn. Carefully follow the lime manufacturer's instructions regarding the amount of lime to add to adjust the soil to exactly the right pH. If you already planted corn in overly acidic soil, you will have to wait until next season to remedy the problem. Make sure to mix lime into the soil thoroughly because it does not dissolve and spread out easily.