Teachers are categorized in four main classes in Bangladesh at University level. The ascending rank of teacher is Lecturer, Assistant Professor, Associate Professor and Professor. The initial position Lecturer is generally enrolled as the top student of the class. Master's degree is required for normal university level Lecturer.
Humus soil is soil made up of decayed organic material. Popularly, it refers to soil that is light in texture, dark brown or black in color, and sweet-smelling.
Humus has a characteristic black or dark brown color and is organic due to an accumulation of organic carbon. Soil scientists use the capital letters O, A, B, C, and E to identify the master horizons, and lowercase letters for distinctions of these horizons.