Lignin Decomposition in Soils

Most of our agricultural plants contain from 10-20 per cent of a complex material, called lignin. It is generally accepted that the rigidity of plant stems is due to this lignin which is found in the walls of the xylem cells. Thus, all of the plant residues added to soils contain an appreciable quantity of lignin. The exact chemical structure of this complex is as yet undetermined. In fact, it is even doubtful whether we can ever obtain one chemical formula which can be said to represent lignin. For the soils worker, however, the importance of lignin lies in the fact that its rate of decomposition in the soil is much slower than that of any of the other constituents of plant residues, and that as a consequence we have a relative accumulation of lignin in the soil