Humus is the penultimate state of decomposition of organic matter; while it may linger for a thousand years, on the larger scale of the age of the other soil components, it is temporary. It is composed of the very stable lignins (30%) and complex sugars (polyuronides, 30%). Its chemical assay is 60% carbon, 5% nitrogen, some oxygen and the remainder hydrogen, sulfur, and phosphorus. On a dry weight basis, the CEC of humus is many times greater than that of clay. Plant roots also have cation exchange sites.
Soil conservation is an effort made by man to prevent soil erosion in order to …