Other reports in this collection 2.2.5.4. The term forest soils is absent but may be considered as part of the forest ecosystem. There are significant differences between agricultural and forest soils that may affect inventory practices. The E, B, C, and R horizon may be lacking, or the B horizon may be modified by groundwater or stagnant water.
Agricultural soils associated with rangelands and grasslands often have similar vertical sequences.
The soils may have been so degraded by past human actions that they are no longer cultivatable. Such soils may still be classified as agricultural soils and used, for example, for grazing or non-cropping production. The thick organic layers of wetlands, which may have peaty horizons of more than 30 cm up to several meters, are a special form of O horizon. Both the topsoil and the subsoil are relevant in the context of carbon sequestration in agricultural soils. The activity of soil biota such as rodents, earthworms, termites, or leaf-cutting ants leads to a dynamic interaction between these two layers and the substratum.