The upper part of a soil profile, above the C horizon, in which the processes of soil formation are active. The solum in soil consists of the A, E, and B horizons. Generally, the characteristics of the material in these horizons are unlike those of the underlying material. The living roots and plant and animal activities are largely confined to the solum.

upper horizons of a soil in which the parent material has been modified and in which most plant roots are contained. It usually consists of A- and B-horizons.

The upper part of a soil profile above the parent material in which current processes of soil formation are active. This is where the living roots and other plant and animal life characteristics are exhibited.

The soil profile above the parent material (C horizon). i.e. the O, A and B horizons.

The upper part of the soil profile, above the C horizon, in which the process of soil formation are active. The solum in soil consists of the A, E, B and BC horizons. The living root and plant and animal activities are largely confined to the solum.

The solum (plural, sola) in soil science consists of the surface and subsoil layers that have undergone the same soil forming conditions. The base of the solum is the relatively unweathered parent material, termed substratum.