What Soil PH Is Best for Maize?

Soil and pH

• Maize grows in a range of soil types but optimally in a well-drained, moist loam with a pH of 5.8 to 6.5, as recommended by the University of Rhode Island Extension. The soil pH is the level of acidity or alkalinity measured on a scale of 0.0 to 14.0. Acidic soil has a pH of less than 7.0, while alkaline soil have a pH higher than 7.0. Pure water has a neutral pH of 7.0.

Importance of pH

• Maintaining the right pH for maize affects the plants' ability to utilize nutrients from the soil. In overly acidic soil, plants are unable to utilize the essential nutrients nitrogen, potassium and phosphorus. Plants also are prone to absorbing toxic metals from the soil in acidic conditions. This leads to toxicity and death. Improper soil pH impedes the proper absorption of disease and weed-controlling pesticides, fungicides or herbicides in the soil, leading to runoff, rather than doing any good for the plants.

Factors Affecting pH

• Cultural management practices continually affect the soil's pH. Test soil on a regular basis and amend as required. Consistent cultivation in a given area and the persistent use of chemical or inorganic fertilizers with high levels of sulfur or ammonium decreases soil pH. Watering maize with irrigation water containing high levels of calcium carbonate increased the soil's pH level.

Amendments

• In soils with a pH level of below 5.7, lime is the recommended amendment to improve pH, as cited by the University of Arkansas Extension. Lime is not recommended without also testing the irrigation water if corn plants are rotated with rice. Recommended amount of lime is 1 ton per acre in a pH of 5.2 to 5.7, 1-½ tons per acre if the pH is 5.0 to 5.2 and 2 tons per acres in pH of 5.0 or below. The best time to apply lime is during fall, as this gives the material enough time to react with the soil.