As weathering proceeds and plants grow on a young soil, several processes are apparent that tendto cause layers, or horizons, to develop in the soil. For example, soils gain material when leaves and plant remains accumulate on the surface. This accumulation is easily seen in areas of Dekalb, Hazleton, and other soils that formed under forest and have not been plowed. Additions of organic matter, chemicals, and mineral material are also brought in from adjacent areas by animals, floodwaters, and wind, or they are transferred as a result of gravity.

Losses from the soil occur when minerals decompose and, as a process in weathering, are leached from the soil. This process is apparent in the Hublersburg and Hagerstown soils, from which calcium carbonate has been leached. Losses also occur when plant nutrients are removed in harvested plants. In addition, fine particles of soil material are removed by erosion, and gases escape as organic matter decomposes.

The transfer or translocation of material from one part of the soil to another is common in mostsoils. Organic matter in suspension or solution is moved from the upper part of the profile to the lower part. Calcium is leached from the surface layer and is held by the clay in the subsoil.The Rayne and Laidig soils are examples of soils in which the results of this process can be seen. In those soils clay has accumulated in the B horizon as a result of transfer of clay from horizons higher in the profile.

Bases and plant nutrients are absorbed by the roots of plants and are moved upward in the stem to be stored in the leaves and twigs. When the plant dies and decays, the plant nutrients are returned to the soil.

Transformations occur as chemical weathering takes place. During weathering, iron, aluminum, calcium, and other elements are released from the primary and secondary minerals in the soil. For example, the gray and white colors of the parent material of a well-drained Hagerstown soil are gradually replaced by the red, brown, and yellow colors of oxidized iron compounds as the parent material weathers. These color changes indicate that iron has been released or that ferrous oxide has been oxidized to ferric oxide in the presence of an adequate supply of oxygen.

10/15/98