THE PROBLEM of establishing plants and keeping them growing on acid soils has been present as long as agriculture has been practised, and the beneficial effect of liming materials of various kinds has been appreciated for almost as long. But while they have been appreciated, their precise mode of action has not been understood. Even with the considerable advances that have been made in understanding the "acidity complex" in recent years, the full solution of the complexities of plant growth on acid soils has still to be found.
