|
|
A wide range of toxicities and nutrient deficiencies can be associated with low soil pH. Aluminum and manganese solubility increases as pH decreases, sometimes to the point of toxicity. Symptoms of both toxicities can include stunted plants, crinkled leaves, and yellow leaves. Soil pH is often lower in subsoil than topsoil. Plants may respond to toxic levels of aluminum or manganese in the subsoil by extensive horizontal spreading of roots just below the soil surface.
Low pH may also result in nitrogen deficiency due to poor nodulation or inhibition of nodule function. This may be due to molybdenum deficiency at low pH, since molybdenum is required for nodules to function. It may also be associated with poor survival of Rhizobia bacteria in the low-pH soil-these bacteria are required for nodulation. Poor root growth associated with aluminum or manganese toxicity may also lead to poor nodulation. Application of agricultural limestone is the most effective way to correct the problem. This problem is most common in southeastern and south-central soybean production areas of the U.S. |