Specialists can be promoted to corporal, the lowest rank of non-commissioned officer, or NCO. An NCO is an enlisted man with the responsibility to lead other soldiers. Corporals lead teams of a few soldiers within a squad. Each squad of as many as 10 soldiers is led by one or more sergeants or a staff sergeant. In squads with a staff sergeant, the staff sergeant commands any other sergeants in the squad.
Organic soil is soil that contains more than 30 percent of decayed organic material from dead leaves, stems and animals, and this material gives the soil a rich color and fibrous texture. Organic soil also receives and retains moisture, which makes it highly supportive for plant growth.
Acid sulfate soil. Acid sulfate soils are naturally occurring soils, sediments or organic substrates (e.g. peat) that are formed under waterlogged conditions. These soils contain iron sulfide minerals (predominantly as the mineral pyrite) or their oxidation products. In an undisturbed state below the water table, acid sulfate soils are benign.