ii) What’s wrong with acid soils?

Soil pH controls the availability of plant nutrients. It can also help or hinder the activity of earthworms, as they prefer to live in a neutral environment, where the soil pH is near 7.
For most agricultural plants, a soil pH (using the CaCl2 scale) of between 5 and 8 provides the best growing conditions.
If the pH drops below 5.0, it has a negative effect on plants (such as lucerne) that are sensitive to acidity.
Plants that are more tolerant of acidity, such as subterranean clover, continue to grow normally until the pH falls below 4.5. Below pH 4.2 all plants, except the very highly acid-tolerant, show a significant reduction in production. Very few plants survive below pH 3.8.