Soil pH Management

The soils are buffered against changes in availability of micronutrients with moderate changes in soil pH. Many soils that are affected by drought are moderately or strongly alkaline and many soils that are affected by mineral stress are strongly acid. Marl is soft and unconsolidated CaCO₃, usually mixed with varying amounts of clay and other impurities. Marl occurs as an amorphous and soft deposit found in poorly drained and low-lying areas. Wood ashes are an ancient soil amendment. Environmental and sustainable agriculture concerns have created renewed interest in the application of wood ashes to the land. Lime requirements for upland rice are determined similarly as for other crops. The neutralization of acidity and the increase in pH result in an increase in the effective action exchange capacity. The ECEC of some low activity clay soils may be increased four or more times by increasing the pH to 7, however, these soils would not normally be limed to pH 7.